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Dedicator of cytokinesis (DOCK) proteins play a central role in actin cytoskeleton regulation. This is highlighted by the DOCK2 and DOCK8 deficiencies leading to actinopathies and immune deficiencies. DOCK8 and DOCK11 activate CDC42, a RHO-GTPase involved in actin cytoskeleton dynamics, among many cellular functions. The role of DOCK11 in human immune disease has been long suspected but has never been described so far. We studied eight male patients, from seven unrelated families, with hemizygous DOCK11 missense variants leading to reduced DOCK11 expression. The patients were presenting with early-onset autoimmunity, including cytopenia, systemic lupus erythematosus, skin, and digestive manifestations. Patients' platelets exhibited abnormal ultrastructural morphology and spreading as well as impaired CDC42 activity. In vitro activated T cells and B lymphoblastoid cell lines (B-LCL) of patients exhibited aberrant protrusions and abnormal migration speed in confined channels concomitant with altered actin polymerization during migration. A DOCK11 knock-down recapitulated these abnormal cellular phenotypes in monocytes-derived dendritic cells (MDDC) and primary activated T cells from healthy controls. Lastly, in line with the patients' autoimmune manifestations, we also observed abnormal regulatory T cells (Tregs) phenotype with profoundly reduced FOXP3 and IKZF2 expression. Moreover, we found a reduced T cell proliferation and an impaired STAT5B phosphorylation upon IL2 stimulation of the patients' lymphocytes. In conclusion, DOCK11 deficiency is a new X-linked immune-related actinopathy leading to impaired CDC42 activity and STAT5 activation, and associated with abnormal actin cytoskeleton remodeling as well as Tregs phenotype culminating in immune dysregulation and severe early-onset autoimmunity.

Clonal hematopoiesis (CH) describes the disproportionate expansion of a hematopoietic stemcell (HSC) and its progeny, in association with leukemia-associated somatic mutations, mostcommonly affecting the genes for epigenetic regulators DNMT3A, TET2 and ASXL1.The prevalence and size of such clones rise with age, in association with changes in the driver gene landscape.10 CH is associated with an increased risk of hematologic malignancies, but also of cardiovascular disease (CVD), independently of other known CVD risk factors.11,12 The basis forthis increased CVD risk has been linked to hyperinflammatory positive feedback loops driven by increased cytokine release from clonal myeloid cells, particularly interleukin IL-6 and IL-1β.

Evans syndrome (ES) is a rare severe autoimmune disorder characterized by the combination of autoimmune hemolytic anemia and immune thrombocytopenia. In most cases, the underlying cause is unknown. We sought to identify genetic defects in pediatric ES (pES), based on a hypothesis of strong genetic determinism. In a national, prospective cohort of 203 patients with early-onset ES (median [range] age at last follow-up: 16.3 years ([1.2-41.0 years]) initiated in 2004, 80 nonselected consecutive individuals underwent genetic testing. The clinical data were analyzed as a function of the genetic findings. Fifty-two patients (65%) received a genetic diagnosis (the M+ group): 49 carried germline mutations and 3 carried somatic variants. Thirty-two (40%) had pathogenic mutations in 1 of 9 genes known to be involved in primary immunodeficiencies (TNFRSF6, CTLA4, STAT3, PIK3CD, CBL, ADAR1, LRBA, RAG1, and KRAS), whereas 20 patients (25%) carried probable pathogenic variants in 16 genes that had not previously been reported in the context of autoimmune disease. Lastly, no genetic abnormalities were found in the remaining 28 patients (35%, the M− group). The M+ group displayed more severe disease than the M− group, with a greater frequency of additional immunopathologic manifestations and a greater median number of lines of treatment. Six patients (all from the M+ group) died during the study. In conclusion, pES was potentially genetically determined in at least 65% of cases. Systematic, wide-ranging genetic screening should be offered in pES; the genetic findings have prognostic significance and may guide the choice of a targeted treatment.

Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is a distinct subset of cutaneous lymphomas in which neoplastic cytotoxic α/β CD8+ T cells infiltrate subcutaneous adipose tissue.1-3 SPTCL may affect both children and adults.4 Systemic symptoms such as fever, asthenia, and weight loss, associated with cytopenias and liver dysfunction, are common. In addition, hemophagocytic lymphohistiocytosis (HLH) is observed in 20% of cases,3 which is associated with poor prognosis and may be the leading cause of death.3 There is no standardized therapy for SPTCL alone or in association with HLH. Chemotherapy with cyclophosphamide, doxorubicin, vincristine, and prednisolone is frequently used, with an overall remission rate of 50%.1 Immunosuppressive regimens, particularly cyclosporine A (CsA), may be also effective.5 In some severe cases, stem cell transplantation has been attempted.1 Recently, germline mutations causing loss of function of T-cell immunoglobulin mucin 3 (TIM-3) were identified in 60% to 85% of SPTCL patients.6,7 In these patients, TIM-3 deficiency was shown to promote T-lymphocyte and -macrophage activation and the production of proinflammatory cytokines, challenging the malignant nature of skin T-lymphocyte infiltration.6 Ruxolitinib is a selective JAK1/JAK2 inhibitor licensed for treatment of myelofibrosis and polycythemia vera in adults.8,9 Studies in animal models of HLH support the efficacy of this drug to prevent and treat HLH in these models.10,11 Anecdotal experiences of successful use of ruxolitinib to control refractory primary HLH or secondary HLH are also reported in humans.12-19 JAK1/JAK2 inhibitors are also increasingly used in inflammatory diseases. We herein report the use and efficacy of ruxolitinib in a patient with recurrence of SPTCL and HLH and in whom TIM-3 deficiency was recently identified.6

Severe combined immunodeficiencies (SCIDs) constitute a heterogeneous group of life-threatening genetic disorders that typically present in the first year of life. Reticular dysgenesis (RD) is an autosomal recessive form of human Severe Combined Immunodeficiency (SCIDs) characterized by the absence of blood neutrophils and T lymphocytes. This pathology is due to biallelic mutations in the adenylate kinase 2 (AK2) gene, encoding for a mitochondrial protein which regulates the homeostasis of adenine nucleotides. In three newborns presenting a RD-like clinical phenotype as frequent infections and a profound leukopenia, we identified an heterozygous dominant missense mutation in the gene coding for Rac Family Small GTPase 2 (RAC2) protein (p.G12R). Hematopoietic stem cell transplantation (HSCT) performed soon after birth was successful in two out of the three patients attesting that the inherited defect was intrinsic and not micro-environmental. RAC2 protein belongs to the Rac subfamily of RHO small GTPases. In the inactive GDP-bound state, RAC2 is located in the cytosol and upon stimulation, the active RAC2-GTP-bound form translocates to the plasma membrane. Unlike the other members of the Rac subfamily (RAC1 and RAC3), RAC2 is mostly expressed on hematopoietic cells and during T cell differentiation. To gain insight into the disease, we transduced human hematopoietic stem and progenitor cells (HSPCs) with a lentiviral construct containing the RAC2 mutated form. The mutation inhibits HSPCs proliferation and differentiation toward the myeloid and lymphoid lineages reproducing the patients' clinical phenotype. In this condition, we also observed high apoptosis level and an alteration of mitochondrial activity and Ros production. In a biochemical model, we demonstrated that the substitution of the glycine (G) amino-acid by a bulky flexible arginine (R) may prevent GTP hydrolysis. Lastly, our findings suggest that RAC2 gene sequencing must be considered in newborn screening programs for SCID detection. To decipher the mechanisms regulating RAC2 functions, we studied the impact of the p.G12R mutation on a human AML cell line expressing RAC2 protein. Our preliminary data highlight that the cell cycle and mitochondrial activity are disrupted by G12R mutation. By holotomography, we also observed morphological changes and accumulation of lipid droplets into the cells. All these data suggest that RAC2 defective signalling pathway is linked to cell metabolism imbalance and further investigations are ongoing to better understand how RAC2 controls cell energy demand, especially during differentiation. Disclosures Cavazzana: Smart Immune: Other: co-founder.

Reticular dysgenesis (RD) is a rare congenital disorder defined clinically by the combination of severe combined immunodeficiency (SCID), agranulocytosis, and sensorineural deafness. Mutations in the gene encoding adenylate kinase 2 were identified to cause the disorder. Hematopoietic stem cell transplantation (HSCT) is the only option to cure this otherwise fatal disease. Retrospective data on clinical presentation, genetics, and outcome of HSCT were collected from centers in Europe, Asia, and North America for a total of 32 patients born between 1982 and 2011. Age at presentation was

The histiocytoses are rare disorders characterized by the accumulation of macrophage, dendritic cell, or monocyte-derived cells in various tissues and organs of children and adults. More than 100 different subtypes have been described, with a wide range of clinical manifestations, presentations, and histologies. Since the first classification in 1987, a number of new findings regarding the cellular origins, molecular pathology, and clinical features of histiocytic disorders have been identified. We propose herein a revision of the classification of histiocytoses based on histology, phenotype, molecular alterations, and clinical and imaging characteristics. This revised classification system consists of 5 groups of diseases: (1) Langerhans-related, (2) cutaneous and mucocutaneous, and (3) malignant histiocytoses as well as (4) Rosai-Dorfman disease and (5) hemophagocytic lymphohistiocytosis and macrophage activation syndrome. Herein, we provide guidelines and recommendations for diagnoses of these disorders.

International audience; The impairment of cytotoxic activity of lymphocytes disturbs immune surveillance and leads to the development of hemophagocytic lymphohistiocytic syndrome (HLH). Although cytotoxic T lymphocyte (CTL) control of HLH development is well documented, the role for natural killer (NK)-cell effector functions in the pathogenesis of this immune disorder remains unclear. In this study, we specifically targeted a defect in cytotoxicity to either CTL or NK cells in mice so as to dissect the contribution of these lymphocyte subsets to HLH-like disease severity after lymphocytic choriomeningitis virus (LCMV) infection. We found that NK-cell cytotoxicity was sufficient to protect mice from the fatal outcome that characterizes HLH-like disease and was also sufficient to reduce HLH-like manifestations. Mechanistically, NK-cell cytotoxicity reduced tissue infiltration by inflammatory macrophages and downmodulated LCMV-specific T-cell responses by limiting hyperactivation of CTL. Interestingly, the critical protective effect of NK cells on HLH was independent of interferon-γ secretion and changes in viral load. Therefore our findings identify a crucial role of NK-cell cytotoxicity in limiting HLH-like immunopathology, highlighting the important role of NK cytotoxic activity in immune homeostasis.

To the editor: In juvenile myelomonocytic leukemia (JMML), activating RAS mutations are responsible for a hyperactive RAS/ERK signaling.[1][1] Somatic codons 12-13-61 RAS mutations are described in cases of RAS -associated lymphoproliferative disease (RALD),[2][2][⇓][3]-[4][4] believed to be a

Background Hemophagocytic lymphohistiocytosis (HLH) is an inflammatory condition caused by uncontrolled proliferation of activated lymphocytes and macrophages secreting an excess of inflammatory cytokines. When untreated, primary HLH is invariably fatal. Treatment requires the achievement of remission of HLH prior to allogeneic hematopoietic stem cell transplantation. Despite significant treatment progress, pre-HSCT mortality remains a challenge. In the Etoposide-based HLH-94 and HLH-2004 studies pre-HSCT mortality was 27% and 19%, respectively. A better understanding of the pathophysiology of primary HLH has opened new avenues for targeted immunotherapy. Based on our previous observation concerning the use of Antithymoglobulin in HLH, we propose a new therapeutic strategy with Alemtuzumab in association with steroids and cyclosporine A (CSA) as first line treatment in primary HLH. In contrast to ATG, Alemtuzumab does not activate T lymphocytes while killing them. Therefore, we expect a better tolerance and efficacy of Alemtuzumab. This may have a positive impact not only on survival until HSCT, but also on overall survival and quality of life, especially with regard to long-term neurological sequelae. Methods 24 consecutive treatment naïve patients with genetically confirmed primary HLH had received first line Alemtuzumab in association to steroids and CSA from 01/2009 to 06/2015 in the Unit for Pediatric Immunology in Necker Hospital Paris, as well as two additional patients in 10/2016 and 10/2018 respectively, who could not be included in the prospective trial. From 06/2015 to 06/2019, 29 patients have been enrolled in a multicenter, open, phase I/II, non-comparative, non randomized study (NCT02472054). Patients with lymphohistiocytic activation syndrome who had not received any specific treatment prior to enrollment except steroids and CSA were included. Treatment consisted in intravenous administration of Alemtuzumab in association to Methylprednisolone and CSA. The primary outcome measures is the number of surviving patients until HSCT, secondary outcome measures the number of complete remissions following treatment at Day (D)14, D21, D28. To assess the efficacy of the Alemtuzumab, the time of delay between the first administration of Alemtuzumab and complete remission will be determined. Alemtuzumab Pharmacokinetics will be done. All adverse events are reported. Results Retrospective analysis of 26 patients (pilot study): The median age of patients was 1.9 months (birth - 7 years), 6 patients were neonates. When Alemtuzumab was started, out of 26 patients 12 (46.1%) required intensive care, 8 (30.7%) mechanical ventilation, 13 (50%) had neurological involvement, 9 (34.6%) hepatocellular insufficiency. One 2-month-old Munc13-4 patient died at H+48 after two administrations of Alemtuzumab (total dose 1.5mg/kg) for hepatic failure and acute renal failure. A second patient with Perforin deficiency did not respond neither to three courses of Alemtuzumab (cumulative dose 6.5mg/kg) nor repeated Etoposid, 40mg/kg ATG, or Ruxulotinib. He died at D+65. The 24 remaining patients survived until HSCT (survival 92.3%). As shown in the figure, two patients required additional treatment. Overall 22 patients achieved CR, 2 PR at the time of HSCT. The prospective study enrolled 29 patients from 06/2015 to 06/2019. Median age at onset of HLH was 0.5 years (range 0.02 to 17.2 years), one patient withdrawed consent. 12 patients received one course, 13 two, 2 three and one patient 4 courses of Alemtuzumab. 24 patients with a genetic confirmed HLH predisposition reached the primary endpoint with 22 surviving until HSCT (91,6%). One patient is still awaiting HSCT. The three remaining patients are one CA-EBV patient and a newborn with secondary HLH due to fulminant HSV hepatitis, who both died, as well as a patient with predominant neurological HLH without genetic diagnosis who is in sustained remission without any specific treatment. Detailed results from the completed study will be presented. Conclusions This is the first report on Alemtuzumab as first line approach in the treatment of primary HLH. Our results in more than 50 pediatric patients treated in a pilot study and prospective trial indicate that Alemtuzumab allows controlling HLH activity with a favorable safety and tolerability profile in a very fragile population. 92.3% and 91.6% of patients respectively survived to HSCT. Figure Disclosures No relevant conflicts of interest to declare. Off Label Disclosure: Alemtuzumab (Campath) has been used in a prospective trial to evaluate its efficacy as first line treatment in Familial Lymphohistiocytosis.

Background: Hemophagocytic lymphohistiocytosis (HLH) syndrome is due to an abnormal and sustained activation of T lymphocytes and macrophages releasing pro-inflammatory cytokines in the microenvironment. HLH is characterized by clinical and biological features that includes fever, hepatomegaly, splenomegaly, high ferritin level, pancytopenia and liver biology abnormalities. HLH is commonly divided into genetic/hereditary cases (HLHg) and non genetic/ sporadic (HLHs) with no hints for an inherited causes. However, similarity of both clinical symptoms and biological abnormalities between HLHg and HLHs raised, however, the hypothesis that HLHs could have a genetic component that may be related to HLHg. However contribution of genetic factors in both, pathophysiology and prognosis of sporadic hemophagocytic lymphohistiocytosis (HLHs) remains unknown. To explore the hypothesis of a genetic susceptibility in HLHs, from 2010 to 2017, we constituted a cohort of 205 HLHs patients (adults and children) and analysed genes involved in genetic HLH (HLHg). Methods: Patients fulfillied modified HLH-2004 diagnostic criteria. Data collected included (i) clinical and biological features, (ii) associated diseases (AID), (iii) infectious events, (iv) treatment, and (v) clinical outcome during one year of follow up. HLHg related genes LYST, PRF1, UNC13-D, STX11, STXBP2, RAB27A, SH2D1A, XIAP were NGS sequenced in 172 patients. Selected variants were (i) unknown but met at least two criteria among MAF10, and/or Polyphen HDIV (>0.485) (n=50), (ii) previously related to HLHg (n=2), PRF1 A755G/N252S (MAF 10 and Polyphen HDIV). Two control cohorts were selected, the first one using the variant files from the European subpopulation of the 1000 Genomes (1000G cohort, n=502) phase 3 project and the second one from the local in-house variants data base (in-house cohort, n=5092). Results: Patients presented with neoplasia (n=62), AID (n=46) in which infection was mainly Herpes virus (EBV) (> 80%), or no etiology (idiopathic) (n=64) with a greater infectious diversity. Fifty-two variants met the selection criteria, they were distributed overall in 115 alleles in 84/172 patients. Variants were globally heterozygous. They were recurrent with occurrence in 2 patients for STX11, RAB27A and LYST genes to 10 patients for the N252S and 18 patients for the p.Ala91Val in PRF1. Overall the frequency of individuals exhibiting at least one variant was significantly in excess (48.8%, n=84) in the HLHs versus in in-house (35.9%, n=1826) (p=0.001, CAST test) or versus in 1000G population patients (38.6%, n=194) (p=0.02, CAST test). Importantly, the distribution of patients carrying either 0, 1, 2, 3 or 4 mutated alleles in HLHs cohort was statistically different from the two control populations (Trend test: HLH vs in-house p Importantly, severe patients carried a significantly higher number of variants (1, 2 or 3) than the one with a better outcome (p Conclusion: The results presented in this study strongly support the hypothesis that HLHs has a genetic component when tested with genes of HLH. Overall, this results established clearly a genotype/phenotype correlation between presence of one or more filtered HLH genes variants and severity of the HLH syndrome in patients. Finally, we proposed a di/tri genic model as an expression of genetic component in sporadic HLH. Disclosures Hermine: Novartis: Research Funding; AB science: Consultancy, Equity Ownership, Honoraria, Research Funding; Celgene: Research Funding.

Severe combined immunodeficiencies (SCIDs) form a heterogeneous group of life-threatening genetic disorders defined by the absence of autologous T cells and an intrinsic or extrinsic defect in the B-cell compartment. In our cohort, three newborn patients with bone-marrow hypoplasia associated with clinical and biological features of SCID received allogenic hematopoietic stem cell transplantation in the first weeks of life. To identify the molecular defect involved in this life threatening SCID form, we performed whole-genome sequencing on patient's fibroblasts. The same heterozygous, dominant missense mutation was found in the RAC2gene encoding for the RAC2 GTPase (p.G12R). By biochemical analyses we demonstrated that arginine substitution at position 12 leads to sustained activation of the RAC2 signalling pathway; the G12R mutation is therefore a gain of function mutation. In cord blood hematopoietic cells, we observed that the mutation disrupts mitochondrial activity and blocks hematopoietic stem/progenitor cells (HSPCs) differentiation toward the myeloid and lymphoid lineages. Altogether, our data emphasize the involvement of the RAC2 signalling pathway during hematopoeisis and might thus explain the severity of the patients' clinical and immunological phenotype. The present study is the first to report an autosomal dominant form of SCID and suggest that RAC2 gene sequencing should be considered for patients with SCID clinical presentation. Disclosures Cavazzana: Smartimmune: Other: Founder of Smartimmune.

Comment in Lymphocyte cytotoxicity: tug-of-war on microtubules. [Blood. 2012]; International audience; Cytotoxic T lymphocytes kill target cells via the polarized secretion of cytotoxic granules at the immune synapse. The lytic granules are initially recruited around the polarized microtubule-organizing center. In a dynein-dependent transport process, the granules move along microtubules toward the microtubule-organizing center in the minus-end direction. Here, we found that a kinesin-1-dependent process is required for terminal transport and secretion of polarized lytic granule to the immune synapse. We show that synaptotagmin-like protein 3 (Slp3) is an effector of Rab27a in cytotoxic T lymphocytes and interacts with kinesin-1 through the tetratricopeptide repeat of the kinesin-1 light chain. Inhibition of the Rab27a/Slp3/kinesin-1 transport complex impairs lytic granule secretion. Our data provide further molecular insights into the key functional and regulatory mechanisms underlying the terminal transport of cytotoxic granules and the latter's secretion at the immune synapse.

In this retrospective collaborative study, we have analyzed long-term outcome and donor cell engraftment in 194 patients with Wiskott-Aldrich syndrome (WAS) who have been treated by hematopoietic cell transplantation (HCT) in the period 1980- 2009. Overall survival was 84.0% and was even higher (89.1% 5-year survival) for those who received HCT since the year 2000, reflecting recent improvement of outcome after transplantation from mismatched family donors and for patients who received HCT from an unrelated donor at older than 5 years. Patients who went to transplantation in better clinical conditions had a lower rate of post-HCT complications. Retrospective analysis of lineage-specific donor cell engraftment showed that stable full donor chimerism was attained by 72.3% of the patients who survived for at least 1 year after HCT. Mixed chimerism was associated with an increased risk of incomplete reconstitution of lymphocyte count and post-HCT autoimmunity, and myeloid donor cell chimerism < 50% was associated with persistent thrombocytopenia. These observations indicate continuous improvement of outcome after HCT for WAS and may have important implications for the development of novel protocols aiming to obtain full correction of the disease and reduce post-HCT complications.

In human B-acute lymphoblastic leukemia (B-ALL), RAG1-induced genomic alterations are important for disease progression. However, given that biallelic loss of the RAG1 locus is observed in a subset of cases, RAG1's role in the development of B-ALL remains unclear. We chose a p19Arf−/−Rag1−/− mouse model to confirm the previously published results concerning the contribution of CDKN2A (p19ARF /INK4a) and RAG1 copy number alterations in precursor B cells to the initiation and/or progression to B-acute lymphoblastic leukemia (B-ALL). In this murine model, we identified a new, Rag1-independent leukemia-initiating mechanism originating from a Sca1+CD19+ precursor cell population and showed that Notch1 expression accelerates the cells' self-renewal capacity in vitro. In human RAG1-deficient BM, a similar CD34+CD19+ population expressed p19ARF. These findings suggest that combined loss of p19Arf and Rag1 results in B-cell precursor leukemia in mice and may contribute to the progression of precursor B-ALL in humans.

X-linked lymphoproliferative syndromes (XLP) are primary immunodeficiencies characterized by a particular vulnerability toward Epstein-Barr virus infection, frequently resulting in hemophagocytic lymphohistiocytosis (HLH). XLP type 1 (XLP-1) is caused by mutations in the gene SH2D1A (also named SAP), whereas mutations in the gene XIAP underlie XLP type 2 (XLP-2). Here, a comparison of the clinical phenotypes associated with XLP-1 and XLP-2 was performed in cohorts of 33 and 30 patients, respectively. HLH (XLP-1, 55%; XLP-2, 76%) and hypogammaglobulinemia (XLP-1, 67%; XLP-2, 33%) occurred in both groups. Epstein-Barr virus infection in XLP-1 and XLP-2 was the common trigger of HLH (XLP-1, 92%; XLP-2, 83%). Survival rates and mean ages at the first HLH episode did not differ for both groups, but HLH was more severe with lethal outcome in XLP-1 (XLP-1, 61%; XLP-2, 23%). Although only XLP-1 patients developed lymphomas (30%), XLP-2 patients (17%) had chronic hemorrhagic colitis as documented by histopathology. Recurrent splenomegaly often associated with cytopenia and fever was preferentially observed in XLP-2 (XLP-1, 7%; XLP-2, 87%) and probably represents minimal forms of HLH as documented by histopathology. This first phenotypic comparison of XLP subtypes should help to improve the diagnosis and the care of patients with XLP conditions.

PV and AL contributed equally Multiple studies from the EBMT registry and others have shown excellent survival rates after allogeneic haematopoietic stem cell transplantation (HSCT)for Wiskott-Aldrich syndrome (WAS) patients (Ozsahin et al, Blood 2008). The importance of myeloid engraftment for full disease correction has also been demonstrated (Moratto et al, Blood 2011). However, the vast majority of HSCTs in these studies were performed with (oral) busulfan/cyclophosphamide-based conditioning and in the early 2000 years or before. In 2005, the inborn errors working party (IEWP) of EBMT and ESID first recommended busulfan/fludarabine (BuFlu) or treosulfan/fludarabine (TreoFlu) based conditioning for primary immunodeficiencies such as WAS, with some centers deciding to add thiotepa (TT) to the conditioning. We performed a retrospective analysis via the EBMT and SCETIDE registries of WAS patients transplanted between 01/01/20006 and 12/31/2016 with these two regimens. The primary objective was to compare the overall (OS) and event-free survival (EFS) after HSCT with either BuFlu±TT or TreoFlu±TT conditioning. Secondary objectives included the influence of either conditioning regimen on acute and chronic GVHD, the degree of donor chimerism, incidence of secondary procedures after HSCT (2nd HSCT, stem cell boost, DLI, gene therapy or splenectomy) and rates of disease-specific complications after HSCT. At the time of this interim analysis, 174 patients were included, 92 (53%) with BuFlu±TT and 82 (47%) with TreoFlu±TT conditioning with a median age of 1.57 years (range 0.21-29.96) at HSCT and a median follow-up of 32.9 months (range 1.5-128.9). The donor was an HLA-matched sibling (MSD) in 30, a matched related donor (MRD) in 5, a matched unrelated donor (MUD, 9/10 or 10/10) in 105, a mismatched unrelated donor (MMUD, 5 years had a worse OS as compared to those 5 years or younger at HSCT (74.9% vs. 90.8%; log-rank test p=0.005). The type of donor had no influence on OS: 96.4% for MSD/MFD, 86.8% for MUD/MMUD and 87.7% for MMFD (log-rank test p=0.4). Whole blood chimerism was complete (>90% donor) in 60/75 evaluable patients (80%) at last follow-up or before secondary procedure (if a patient had one), 39/40 (98%) in the BuFlu±TT group and 21/35 (60%) in the TreoFlu±TT group. Twenty-six patients required a secondary procedure: stem cell boost in 4 patients, donor lymphocyte infusion in 9, 2nd HSCT in 15 and splenectomy in 1. Twenty-two of these 26 (84.6%) are alive and 14 of 16 with available chimerism data have a complete donor chimerism (>90%donor) at last follow-up. The 2-year cumulative incidence (CI) of secondary procedures was higher at 33.9% in the TreoFlu±TT versus 12.8% in the BuFlu±TT group (Gray's test p=0.017), and 2-year EFS (secondary procedure or death as event) was 61.4% in the TreoFlu±TT and 75.0% in the BuFlu±TT group (log-rank test p=0.2). Grade II-IV acute GVHD had the same incidence in both groups (100 day CI 24.4% vs. 26.3%; Gray's test p=0.849) and chronic GVHD of any grade was borderline more frequent in the TreoFlu±TT group (2 year CI 17.2% vs 6.7%; Gray's test p=0.054). The cumulative incidence of disease-specific complications occurring more than 6 months post HSCT (severe infections, bleeding, autoimmunity) was not different between the two groups (6.5% vs. 6.4%; Gray's test p=0.92). There was no malignancy reported after HSCT except for one EBV-post-transplant lymphoproliferative disorder (PTLD) 2.7 months after HSCT. In summary, HSCT with either BuFlu±TT or TreoFlu±TT conditioning reliably cures almost 90% of patients with WAS regardless of donor type. WAS-related complications are very rare events more than 6 months post HSCT. More patients required secondary procedures after treosulfan-based than busulfan-based conditioning. These data confirm the feasibility and efficacy of the regimens currently recommended by the IEWP. Disclosures Slatter: Medac: Other: Travel assistance. Chiesa:Gilead: Consultancy; Bluebird Bio: Consultancy. Kalwak:Sanofi: Other: travel grants; medac: Other: travel grants. Locatelli:Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; bluebird bio: Consultancy; Bellicum: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Miltenyi: Honoraria. Sykora:Aventis-Behring: Research Funding; medac: Research Funding. Zecca:Chimerix: Honoraria. Veys:Pfizer: Honoraria; Servier: Research Funding; Novartis: Honoraria.

Seventeen patients transplanted with hematopoietic cells to correct severe T lymphocyte immunodeficiency resulting from complete DiGeorge anomaly were identified worldwide, and retrospective data were obtained using a questionnaire-based survey. Patients were treated at a median age of 5 months (range, 2-53 months) between 1995 and 2006. Bone marrow was used in 11 procedures in 9 cases: 6 from matched unrelated donors, 4 from human leukocyte antigen (HLA)-identical siblings, and one haploidentical parent with T-cell depletion. Unmobilized peripheral blood was used in 8 cases: 5 from HLA-identical siblings, one from a matched unrelated donor, one from an HLA-identical parent, and one unrelated matched cord blood. Conditioning was used in 5 patients and graft-versus-host disease prophylaxis in 11 patients. Significant graft-versus-host disease occurred in 9 patients, becoming chronic in 3. Median length of follow-up was 13 months, with transplantation from HLA-matched sibling showing the best results. Median survival among deceased patients (10 patients) was 7 months after transplantation (range, 2-18 months). The overall survival rate was 41%, with a median follow-up of 5.8 years (range, 4-11.5 years). Among survivors, median CD3 and CD4 counts were 806 (range, 644-1224) and 348 (range, 225-782) cells/mm3, respectively, CD4+/CD45RA+ cells remained very low, whereas mitogen responses were normalized.

Activation-induced cell death (AICD) is involved in peripheral tolerance by controlling the expansion of repeatedly stimulated T cells via an apoptotic Fas (CD95; APO-1)–dependent pathway. The TNFRSF-6 gene encoding Fas is mutated in children suffering from autoimmune lymphoproliferative syndrome (ALPS), which is characterized by lymphoproliferation and autoimmunity. We examined AICD in Fas-deficient T cells from ALPS patients. We showed that primary activated Fas-deficient T cells die by apoptosis after repeated T cell antigen receptor (TCR) stimulation despite resistance to Fas-mediated cell death. This Fas-independent AICD was found to be mediated through a cytotoxic granules-dependent pathway. Cytotoxic granules-mediated AICD was also detected in normal T lymphocytes though to a lesser extent. As expected, the cytotoxic granules-dependent AICD was abolished in T cells from Rab27a- or perforin-deficient patients who exhibited defective granules-dependent cytotoxicity. Supporting an in vivo relevance of the cytotoxic granules-dependent AICD in ALPS patients, we detected an increased number of circulating T lymphocytes expressing granzymes A and B. Altogether, these data indicated that the cytotoxic granules-dependent cell death in ALPS may compensate for Fas deficiency in T lymphocytes. Furthermore, they identified a novel AICD pathway as a unique alternative to Fas apoptosis in human peripheral T lymphocytes.

Severe combined immunodeficiency (SCID) caused by mutations in RAG1 or RAG2 genes is characterized by a complete block in T- and B-cell development. The only curative treatment is allogeneic hematopoietic stem cell transplantation, which gives a high survival rate (90%) when an HLA-genoidentical donor exists but unsatisfactory results when only partially compatible donors are available. We have thus been interested in the development of a potential alternative treatment by using retroviral gene transfer of a normal copy of RAG1 cDNA. We show here that this approach applied to RAG-1-deficient mice restores normal B- and T-cell function even in the presence of a reduced number of mature B cells. The reconstitution is stable over time, attesting to a selective advantage of transduced progenitors. Notably, a high transgene copy number was detected in all lymphoid organs, and this was associated with a risk of lymphoproliferation as observed in one mouse. Altogether, these results demonstrate that correction of RAG-1 deficiency can be achieved by gene therapy in immunodeficient mice but that human application would require the use of self-inactivated vector to decrease the risk of lymphoproliferative diseases.

CD40 ligand (CD40L) deficiency causes recurrent sinopulmonary infection, Pneumocystis carinii pneumonia, and Cryptosporidium parvum infection. Approximately 40% to 50% of patients survive to the third decade: long-term survival is unclear. Hematopoietic stem cell transplantation (HSCT) is curative. We present a retrospective analysis of 38 European patients undergoing HSCT for CD40L deficiency in 8 European countries between 1993 and 2002. Donor stem cell source included 14 HLA-identical siblings, 22 unrelated donors, and 2 phenotypically matched parental stem cells (12 T-cell depleted). Of the patients, 34 engrafted and 26 (68%) survived; 3 had autologous reconstitution, 22 (58%) were cured, and 1 engrafted but has poor T-cell immune reconstitution. There were 18 evaluated patients who responded to vaccination. Of the patients, 12 (32%) died from infection-related complications, with severe cryptosporidiosis in 6. Grades 2 to 4 graft-versus-host disease (GvHD) associated with infection occurred in 6 of 12 fatal cases. HSCT cured 58% of patients, 72% of those without hepatic disease. Early T-cell function following whole marrow HSCT may limit cryptosporidial disease, but survival was similar after T-cell-depleted HSCT. Preexisting lung damage was the most important adverse risk factor. Further studies will determine optimal timing and type of HSCT.

To the editor: X-linked severe combined immunodeficiency (SCID-Xl) is caused by defects in IL2RG , the gene encoding the IL-2 receptor γ chain. Accounting for 50% to 60% of cases of SCID,[1][1] it SCID-XI is typically characterized by an absence of mature T and natural killer (NK) lymphocytes

Dying cells, apoptotic or necrotic, are swiftly eliminated by professional phagocytes. We previously reported that CD47 engagement by CD47 mAb or thrombospondin induced caspase-independent cell death of chronic lymphocytic leukemic B cells (B-CLL). Here we show that human immature dendritic cells (iDCs) phagocytosed the CD47 mAb–killed leukemic cells in the absence of caspases 3, 7, 8, and 9 activation in the malignant lymphocytes. Yet the dead cells displayed the cytoplasmic features of apoptosis, including cell shrinkage, phosphatidylserine exposure, and decreased mitochondrial transmembrane potential (ΔΨm). CD47 mAb–induced cell death also occurred in normal resting and activated lymphocytes, with B-CLL cells demonstrating the highest susceptibility. Importantly, iDCs and CD34+ progenitors were resistant. Structure-function studies in cell lines transfected with various CD47 chimeras demonstrated that killing exclusively required the extracellular and transmembrane domains of the CD47 molecule. Cytochalasin D, an inhibitor of actin polymerization, and antimycin A, an inhibitor of mitochondrial electron transfer, completely suppressed CD47-induced phosphatidylserine exposure. Interestingly, CD47 ligation failed to induce cell death in mononuclear cells isolated from Wiskott-Aldrich syndrome (WAS) patients, suggesting the involvement of Cdc42/WAS protein (WASP) signaling pathway. We propose that CD47-induced caspase-independent cell death be mediated by cytoskeleton reorganization. This form of cell death may be relevant to maintenance of homeostasis and as such might be explored for the development of future therapeutic approaches in lymphoid malignancies.

Omenn syndrome (OS) is an inherited disorder characterized by an absence of circulating B cells and an infiltration of the skin and the intestine by activated oligoclonal T lymphocytes, indicating that a profound defect in the lymphoid developmental program could be accountable for this condition. Inherited mutations in either the recombination activating genes RAG1 orRAG2, resulting in partial V(D)J recombinase activity, were shown to be responsible for OS. This study reports on the characterization of new RAG1/2 gene mutations in a series of 9 patients with OS. Given the occurrence of the same mutations in patients with T-B–severe combined immune deficiency or OS on 3 separate occasions, the proposal is made that an additional factor may be required in certain circumstances for the development of the Omenn phenotype. The nature of this factor is discussed.

Severe T-cell immunodeficiency after solid organ or bone marrow transplantation may result in the uncontrolled outgrowth of latently Epstein-Barr virus-infected B cells, leading to B-lymphoproliferative disorder (BLPD). Given the potentially important pathogenic role of IL-6 in BLPD, it was tested whether the in vivo neutralization of IL-6 by a monoclonal anti-IL-6 antibody could contribute to the control of BLPD. Safety and efficacy were assessed in 12 recipients of transplanted organs who had BLPD refractory to the reduction of immunosuppression over 8 days. Five patients received 0.4 mg/kg per day. The next 7 patients received 0.8 mg/kg per day. Treatment was scheduled to last 15 days. It was completed in 10 patients, and in the other 2 patients was discontinued early (days 10 and 13, respectively) because of disease progression. Treatment tolerance was good, and no major side effects were observed. High C-reactive protein levels were found in 9 patients before treatment but were normalized under treatment in all patients, demonstrating efficient IL-6 neutralization. Complete remission (CR) was observed in 5 patients and partial remission (PR) in 3 patients. Relapse was observed in 1 of these 8 patients in whom remission was observed. This relapse was unresponsive to treatment. Disease was stable in 1 patient, but it progressed in 3 patients. Seven patients are alive and well. Two patients died because of disease progression, and 3 patients died while in CR (chronic rejection in 2 patients and BLPD sequelae in 1 patient). These data suggest that the anti-IL-6 antibody is safe and should be further explored in the treatment of BLPD.

Mutations in the gene encoding the common cytokine receptor gamma chain (γc) are responsible for human X-linked severe combined immunodeficiency disease (SCIDX1). We have used a γc-deficient mouse model to test the feasibility and potential toxicity of γc gene transfer as a therapy for SCIDX1. A retrovirus harboring the murine γc chain was introduced into γc-deficient bone marrow cells, which were then transplanted into alymphoid RAG2/γcdouble-deficient recipient mice. Circulating lymphocytes appeared 4 weeks postgraft and achieved steady-state levels by 8 weeks. The mature lymphocytes present in the grafted mice had integrated the γc transgene, expressed γc transcripts, and were able to proliferate in response to γc-dependent cytokines. The γc-transduced animals demonstrated (1) normal levels of immunoglobulin subclasses, including immunoglobulin G1 (IgG1) and IgG2a (which are severely decreased in γc- mice); (2) the ability to mount an antigen-specific, T-dependent antibody response showing effective in vivo T-B cell cooperation, and (3) the presence of gut-associated cryptopatches and intraepithelial lymphocytes. Importantly, peripheral B and T cells were still present 47 weeks after a primary graft, and animals receiving a secondary graft of γc-transduced bone marrow cells demonstrated peripheral lymphoid reconstitution. That γc gene transfer to hematopoietic precursor cells can correct the immune system abnormalities in γc- mice supports the feasibility of in vivo retroviral gene transfer as a treatment for human SCIDX1.

Mutations in the gene encoding the common cytokine receptor gamma chain (γc) are responsible for human X-linked severe combined immunodeficiency disease (SCIDX1). We have used a γc-deficient mouse model to test the feasibility and potential toxicity of γc gene transfer as a therapy for SCIDX1. A retrovirus harboring the murine γc chain was introduced into γc-deficient bone marrow cells, which were then transplanted into alymphoid RAG2/γcdouble-deficient recipient mice. Circulating lymphocytes appeared 4 weeks postgraft and achieved steady-state levels by 8 weeks. The mature lymphocytes present in the grafted mice had integrated the γc transgene, expressed γc transcripts, and were able to proliferate in response to γc-dependent cytokines. The γc-transduced animals demonstrated (1) normal levels of immunoglobulin subclasses, including immunoglobulin G1 (IgG1) and IgG2a (which are severely decreased in γc- mice); (2) the ability to mount an antigen-specific, T-dependent antibody response showing effective in vivo T-B cell cooperation, and (3) the presence of gut-associated cryptopatches and intraepithelial lymphocytes. Importantly, peripheral B and T cells were still present 47 weeks after a primary graft, and animals receiving a secondary graft of γc-transduced bone marrow cells demonstrated peripheral lymphoid reconstitution. That γc gene transfer to hematopoietic precursor cells can correct the immune system abnormalities in γc- mice supports the feasibility of in vivo retroviral gene transfer as a treatment for human SCIDX1.

The Wiskott-Aldrich syndrome (WAS) is an X-linked hereditary disease characterized by thrombocytopenia with small platelet size, eczema, and increased susceptibility to infections. The gene responsible for WAS was recently cloned. Although the precise function of WAS protein (WASP) is unknown, it appears to play a critical role in the regulation of cytoskeletal organization. The platelet defect, resulting in thombocytopenia and small platelet size, is a consistent finding in patients with mutations in the WASP gene. However, its exact mechanism is unknown. Regarding WASP function in cytoskeletal organization, we investigated whether these platelet abnormalities could be due to a defect in proplatelet formation or in megakaryocyte (MK) migration. CD34+ cells were isolated from blood and/or marrow of 14 WAS patients and five patients with hereditary X-linked thrombocytopenia (XLT) and cultured in serum-free liquid medium containing recombinant human Mpl-L (PEG-rHuMGDF) and stem-cell factor (SCF) to study in vitro megakaryocytopoiesis. In all cases, under an inverted microscope, normal MK differentiation and proplatelet formation were observed. At the ultrastructural level, there was also no abnormality in MK maturation, and normal filamentous MK were present. Moreover, the in vitro produced platelets had a normal size, while peripheral blood platelets of the same patients exhibited an abnormally small size. However, despite this normal platelet production, we observed that F-actin distribution was abnormal in MKs from WAS patients. Indeed, F-actin was regularly and linearly distributed under the cytoplasmic membrane in normal MKs, but it was found concentrated in the center of the WAS MKs. After adhesion, normal MKs extended very long filopodia in which WASP could be detected. In contrast, MKs from WAS patients showed shorter and less numerous filopodia. However, despite this abnormal filopodia formation, MKs from WAS patients normally migrated in response to stroma-derived factor-1 (SDF-1), and actin normally polymerized after SDF-1 or thrombin stimulation. These results suggest that the platelet defect in WAS patients is not due to abnormal platelet production, but instead to cytoskeletal changes occuring in platelets during circulation.

B-lymphoproliferative disorder (BLPD) is a rare but severe complication of organ and bone marrow transplantation (BMT). Profound cytotoxic T-cell deficiency is thought to allow the outgrowth of Epstein-Barr virus–transformed B cells. When possible, reduction of immunosuppressive treatment or surgery for localized disease may cure BLPD. Therapeutic approaches using chemotherapy or antiviral drugs have limited effects on survival. Adoptive immunotherapy with donor T-cell infusions has given promising results in BMT recipients. We previously reported that administration of two monoclonal anti–B-cell antibodies (anti-CD21 and anti-CD24) could contribute to the control of oligoclonal BLPD. Here we report the long-term results of treatment with these monoclonal anti–B-cell antibodies for cases of severe BLPD. In an open multicenter trial, 58 patients in whom aggressive B-cell lymphoproliferative disorder developed after BMT (n = 27) or organ (n = 31) transplantation received 0.2 mg/kg/d of specific anti-CD21 and anti-CD24 murine monoclonal antibodies (MoAbs) for 10 days. The treatment was well tolerated. Thirty-six of the 59 episodes of BLPD in the 58 patients presented complete remission (61%). The relapse rate was low (3 of 36, 8%). Multivariate analysis identified the following risk factors for partial or no response to anti–B-cell MoAb therapy: multivisceral disease (P ≤ .005), central nervous system involvement (P ≤ .05), and late onset of BLPD (P ≤ .005). The overall long-term survival was 46% (median follow-up, 61 months); it was lower among BMT patients (35%) than organ transplant patients (55%). None of the patients who had received BMT for hematological malignancy survived for 1 year. Eight of these 11 patients presented monoclonal BLPD. Tumor burden was the only other variable that contributed significantly to poor survival. Thus, as assessed from this long-term study, the use of anti–B-cell MoAbs therefore appears to be a safe and relatively effective therapy for severe posttransplant BLPD.© 1998 by The American Society of Hematology.

Familial hemophagocytic lymphohistiocytosis (FHL) is a rare genetic disorder associated with the onset early in life of overwhelming activation of T lymphocytes and macrophages invariably leading to death. Allogeneic bone marrow transplantation (BMT) from an HLA-identical related donor is the treatment of choice in patients with this disease. However, fewer than 20% of patients have a disease-free HLA-identical sibling. BMT from HLA-nonidentical related donors has previously met with poor results, with graft rejection a major obstacle in all cases. We describe BMTs from HLA-nonidentical related donors (n = 13) and from a matched unrelated donor (n = 1) performed in two centers in 14 consecutive cases of FHL. Remission of disease was achieved before BMT in 10 patients. Marrow was T-cell–depleted to minimize graft-versus-host disease (GVHD). Antiadhesion antibodies specific for the α chain of the leukocyte function–associated antigen-1 (LFA-1, CD11a) and the CD2 molecules were infused pre-BMT and post-BMT to help prevent graft rejection, in addition to a conditioning regimen of busulfan (BU), cyclophosphamide (CP), and etoposide (VP16) or antithymocyte globulin (ATG). Sustained engraftment was obtained in 11 of 17 transplants (3 patients had 2 transplants) and disease-free survival in 9 patients with a follow-up period of 8 to 69 months (mean, 33). Acute GVHD greater than stage I was not observed, and 1 patient had mild cutaneous chronic GVHD that resolved. Toxicity due to the BMT procedure was low. Results obtained using this protocol are promising in terms of engraftment and event-free survival within the limitations of the small sample. We conclude that an immunologic approach in terms of drugs used to obtain disease remission and a conditioning regimen that includes antiadhesion molecules in T-cell–depleted BMT from HLA genetically nonidentical donors is an alternative treatment that warrants further study in FHL patients who lack a suitable HLA genetically identical donor.

We have retrospectively assessed the neurological manifestations in 34 patients with hemophagocytic lymphohistiocytosis (HLH) in a single center. Clinical, radiological, and cerebrospinal fluid (CSF ) cytology data were analyzed according to treatment modalities. Twenty-five patients (73%) had evidence of central nervous system (CNS) disease at time of diagnosis, stressing the frequency of CNS involvement early in the time course of HLH. Four additional patients who did not have initial CNS disease, who did not die early from HLH complications, and who were not transplanted, also developed a specific CNS disease. Therefore, all surviving and nontransplanted patients had CNS involvement. Initially, CNS manifestations consisted of isolated lymphocytic meningitis in 20 patients and meningitis with clinical and radiological neurological symptoms in nine patients. For these nine patients, neurological symptoms consisted of seizures, coma, brain stem symptoms, or ataxia. The outcome of patients treated by systemic and intrathecal chemotherapy and/or immunosuppression exclusively (n = 16) was poor, as all died following occurrence of multiple relapses or CNS disease progression in most cases. Bone marrow transplantation (BMT) from either an HLA identical sibling (n = 6) or haplo identical parent (n = 3) was performed in nine patients, once first remission of CNS and systemic disease was achieved. Seven are long-term survivors including three who received an HLA partially identical marrow. All seven are off treatment with normal neurological function and cognitive development. In four other patients, BMT performed following CNS relapses was unsuccessful. Given the frequency and the poor outcome of CNS disease in HLH, BMT appears, therefore, to be the only available treatment procedure that is capable of preventing HLH CNS disease progression and that can result in cure when performed early enough after remission induction.

Three patients with Chediak-Higashi syndrome underwent allogeneic bone marrow transplantation between the ages of 2 years 9 months and 7 years. The outcome was uneventful, with sustained mixed chimerism. No subsequent recurrent infections or hemophagocytic syndrome were observed. At the age of 22 to 24 years, these 3 patients developed a neurologic deficit combining difficulty walking, loss of balance, and tremor. Neurologic evaluation demonstrated cerebellar ataxia and signs of peripheral neuropathy. Moderate axon loss and rarefaction of large myelinated fibers were observed on semithin sections of peripheral nerve. Cerebellar atrophy was detected by cerebral magnetic resonance imaging in 2 patients. We also reviewed the very long-term outcome of the other 11 patients with Chediak-Higashi syndrome who had received bone marrow transplants at our center since 1981. All displayed neurologic deficits or low cognitive abilities.

Gene therapy has been shown to be a highly effective treatment for infants with typical X-linked severe combined immunodeficiency (SCID-X1, γc-deficiency). For patients in whom previous allogeneic transplantation has failed, and others with attenuated disease who may present later in life, the optimal treatment strategy in the absence of human leukocyte antigen (HLA)–matched donors is unclear. Here we report the failure of gene therapy in 2 such patients, despite effective gene transfer to bone marrow CD34+ cells, suggesting that there are intrinsic host-dependent restrictions to efficacy. In particular, there is likely to be a limitation to initiation of normal thymopoiesis, and we therefore suggest that intervention for these patients should be considered as early as possible.

We report transplantation outcomes of 258 children with Hurler syndrome (HS) after a myeloablative conditioning regimen from 1995 to 2007. Median age at transplant was 16.7 months and median follow-up was 57 months. The cumulative incidence of neutrophil recovery at day 60 was 91%, acute graft-versus-host disease (GVHD) (grade II-IV) at day 100 was 25%, and chronic GVHD and 5 years was 16%. Overall survival and event-free survival (EFS) at 5 years were 74% and 63%, respectively. EFS after HLA-matched sibling donor (MSD) and 6/6 matched unrelated cord blood (CB) donor were similar at 81%, 66% after 10/10 HLA-matched unrelated donor (UD), and 68% after 5/6 matched CB donor. EFS was lower after transplantation in 4/6 matched unrelated CB (UCB) (57%; P = .031) and HLA-mismatched UD (41%; P = .007). Full-donor chimerism (P = .039) and normal enzyme levels (P = .007) were higher after CB transplantation (92% and 98%, respectively) compared with the other grafts sources (69% and 59%, respectively). In conclusion, results of allogeneic transplantation for HS are encouraging, with similar EFS rates after MSD, 6/6 matched UCB, 5/6 UCB, and 10/10 matched UD. The use of mismatched UD and 4/6 matched UCB was associated with lower EFS.

There have been no studies on patient outcome after allogeneic hematopoietic cell transplantation (HCT) in patients with X-linked inhibitor of apoptosis (XIAP) deficiency. To estimate the success of HCT, we conducted an international survey of transplantation outcomes. Data were reported for 19 patients. Seven patients received busulfan-containing myeloablative conditioning (MAC) regimens. Eleven patients underwent reduced intensity conditioning (RIC) regimens predominantly consisting of alemtuzumab, fludarabine, and melphalan. One patient received an intermediate-intensity regimen. Survival was poor in the MAC group, with only 1 patient surviving (14%). Most deaths were from transplantation-related toxicities, including venoocclusive disease and pulmonary hemorrhage. Of the 11 patients who received RIC, 6 are currently surviving at a median of 570 days after HCT (55%). Preparative regimen and HLH activity affected outcomes, and of RIC patients reported to be in remission from HLH, survival is 86% (P = .03). We conclude that MAC regimens should not be used for patients with XIAP deficiency. It is possible that the loss of XIAP and its antiapoptotic functions contributes to the high incidence of toxicities observed with MAC regimens. RIC regimens should be pursued with caution and, if possible, efforts should be made to ensure HLH remission before HCT in these patients.

Chediak-Higashi syndrome is a rare condition characterized by susceptibility to bacterial infections, defective natural killer activity, and episodes of macrophage activation known as accelerated phases. Chemotherapy can induce transient remission of the accelerated phase, but relapses become less and less sensitive to treatment and ultimately lead to death. Allogenic bone marrow transplantation (BMT) has been proposed as a curative treatment for Chediak-Higashi syndrome. We report the outcome of BMT in 10 such children. Seven received marrow from an HLA-identical related donor and three from an HLA-nonidentical related donor. Three patients died, two from a new accelerated phase after rejection of transplanted bone marrow and one from cytomegalovirus (CMV) pneumonia. Six of seven recipients of HLA-identical marrow and one of three recipients of HLA-nonidentical marrow are alive and well without treatment 1.5 to 13 years after transplantation (median, 6.5 years). No manifestations of accelerated phases have occurred in these seven patients, and significant natural killer activity is detectable. Interestingly, BMT prevented recurrence of accelerated phases in patients with limited numbers of donor-type leukocytes after transplantation. Ocular and cutaneous albinism were not corrected after transplantation. None of the patients developed serious toxic reactions to the BMT conditioning regimen or have long-term sequelae. These results show that HLA-identical BMT is an acceptable curative treatment for Chediak-Higashi syndrome, whereas HLA-nonidentical BMT remains an experimental approach.

We investigated a T-cell activation deficiency in a 3-month-old boy with protracted diarrhea, serious cytomegalovirus pneumonia, and a family history (in a brother) of cytomegalovirus infection and toxoplasmosis. In spite of detection of normal number of peripheral lymphocytes, T cells did not proliferate after activation by anti-CD3 and anti-CD2 antibodies, although proliferation induced by antigens was detectable. We sought to determine the origin of this defect as it potentially represented a valuable tool to analyze T-cell physiology. T- cell activation by anti-CD3 antibody or phytohemagglutinin (PHA) led to reduced interleukin-2 (IL-2) production and abnormal nuclear factor- activated T cell (NF-AT; a complex regulating the IL-2 gene transcription) binding activity to a specific oligonucleotide. T-cell proliferation was restored by IL-2. Early events of T-cell activation, such as anti-CD3 antibody-induced cellular protein tyrosine phosphorylation, p59fyn and p56lck kinase activities, and phosphoinositide turnover, were found to be normal. In contrast, anti- CD3 antibody-induced Ca2+ flux was grossly abnormal. Release from endoplasmic reticulum stores was detectable as tested in the presence of anti-CD3 antibody or thapsigargin after cell membrane depolarization in a K+ rich medium, whereas extracellular entry of Ca2+ was defective. The latter abnormality was not secondary to defective K+ channel function, which was found to be normal. A similar defect was found in other hematopoietic cell lineages and in fibroblasts as evaluated by both cytometry and digital video imaging experiments at a single-cell level. This primary T-cell immunodeficiency appears, thus, to be due to defective Ca2+ entry through the plasma membrane. The same abnormality did not alter B-cell proliferation, platelet function, and polymorphonuclear neutrophil (PMN) function. Elucidation of the mechanism underlying this defect would help to understand the physiology of Ca2+ mobilization in T cells.

Major histocompatibility complex (MHC) class II deficiency (bare lymphocyte syndrome) is a rare inborn error of the immune system characterized by impaired antigen presentation and combined immunodeficiency. It causes severe and unremitting infections leading to progressive liver and lung dysfunctions and death during childhood. As in other combined immunodeficiency disorders, bone marrow transplantation (BMT) is considered the treatment of choice for MHC class II deficiency. We analyzed the files of 19 patients who have undergone BMT in our center. Of the 7 patients who underwent HLA- identical BMT, 3 died in the immediate posttransplant period of severe viral infections, whereas the remaining 4 were cured, with recovery of normal immune functions. Of the 12 patients who underwent HLA-haplo- identical BMT, 3 were cured, 1 was improved by partial engraftment, 7 died of infectious complications due to graft failure or rejection, and 1 is still immunodeficient because of engraftment failure. A favorable outcome in the HLA-non-identical BMT group was associated with an age of less than 2 years at the time of transplantation. All the patients with stable long-term engraftment had persistently low CD4 counts after transplantation (105 to 650/microL at last follow up), but no clear susceptibility to opportunistic infections despite persisting MHC class II deficiency on thymic epithelium and other nonhematopoietic cells. We conclude that HLA-identical and -haploidentical BMT can cure MHC class II deficiency, although the success rate of haploidentical BMT is lower than that in other combined immunodeficiency syndromes. HLA- haploidentical BMT should preferably be performed in the first 2 years of life, before the acquisition of chronic virus carriage and sequelae of infections.

Chronic granulomatous disease (CGD) is an inherited disorder characterized by recurrent infections and deregulated inflammatory responses. CGD is caused by mutations in subunits of the NADPH oxidase, an enzyme that generates reactive oxygen species in phagocytes. To elucidate the contribution of the proinflammatory protease caspase-1 to aberrant inflammatory reactions in CGD, we analyzed cells isolated from patients with defects in the phagocyte oxidase subunits p22phox, p47phox or gp91phox. We report that mononuclear phagocytes from CGD patients activated caspase-1 and produced biologically active interleukin-1β (IL-1β) in response to danger signals. Notably, caspase-1 activation and IL-1β secretion from CGD monocytes was elevated in asymptomatic patients and strongly increased in patients with noninfectious inflammatory conditions. Treatment with IL-1 receptor antagonist reduced IL-1 production in monocytes ex vivo and during medical therapy. Our results identify phagocyte oxidase defective monocytes as a source of elevated IL-1 and provide a potential therapeutic option to ameliorate inflammatory conditions associated with CGD.

Background. Wiskott Aldrich Syndrome (WAS) is a rare primary immunodeficiency associated with thrombocytopenia, eczema, severe infectious and autoimmune complications, and lymphomas. Mismatched allogeneic hematopoietic stem cell transplantation (HSCT) is an alternative for patient lacking an HLA-matched donor but is associated with an increased frequency of complications. Moreover low lymphoid and myeloid chimerism is related to a higher rate of autoimmunity and thrombocytopenia. Recent gene therapy (GT) trials showed that gene-corrected autologous CD34+ cells infusion could be an appropriate therapeutic approach for these patients. It has been recently shown that B cell homeostasis is altered in WAS. As the B cell reconstitution participates to the restoration of immunological competence, a comprehensive study of this compartment after GT and the comparison with mismatched allogeneic HSCT is crucial. Objective. To perform a longitudinal study of B cell reconstitution in WAS patients after lentiviral vector-mediated GT, compared to mismatched allogeneic HSCT. Methods. Five patients (age 0.8-15.5 years) underwent GT at our center since 2011(follow-up 1.5-4.2 years) after near-myeloablative and immunosuppressive conditioning regimen with (n=3) or without (n=2) anti-CD20 administration. Patient 2 (P2) died 7 months after GT from a pre-existing infectious complication. Eleven patients undergoing mismatched allogeneic HSCT (age 0.6-10.9 years) at the same center were studied (follow-up 5.1-14.7 years). Longitudinal B cell assessment included B cell count before and after treatment, and the following subsets: switched memory (SM, CD19+ CD27+ IgD-), marginal zone (MZ, CD19+ CD27+ IgD+), naives (CD19+ CD27- IgD+), transitional (CD19+ CD27- IgD+ CD24high CD38high), circulating plasma cells (CD19+ CD27+ IgD- CD27high CD38high) and CD21low B cells (CD19+ CD21low CD38-), a subset abnormally expanded in WAS. Quantification of the B cell replication history was assessed through k-deleting recombination excision circles (KRECs). Analyses were compared to age-matched controls. WAS protein (WASP) expression and vector copy number (VCN) were measured in sorted B cells. Results. All alive GT patients show stable engraftment of functionally corrected lymphoid cells, without adverse events. Transduced B cells number and WASP expression increased progressively after GT. Absolute B cell count attained normal values in all the patients, and correlates with WASP expression and VCN in B cells. IgM levels are below normal ranges in four patients. P3 and P4 attained a B-cell phenotype within normal ranges; P3 discontinued intravenous immunoglobulin (IvIg) replacement. No expansion of CD21low B cells was observed. P1 and P5 (follow-up 18 months) present a variable defect in SM, naives and/or MZ B cells. P1 recently developed autoimmune manifestations; no significant changes were observed concomitantly. A defect in B cell lymphopoiesis was observed before GT as measured by KRECs analysis, normalizing after GT (P1, P3 and P4). Several complications were recorded in patients undergoing mismatched allogeneic HSCT, including dysimmunity, arthritis, developmental deficit and infections. Total B cell count normalized in eight patients, IgM levels were low in three. Among patients with available information, four still remain under IvIg replacement. Four patients developed a mixed lymphoid and myeloid chimerism, variably associated with low B cell count, low IgM and IvIg replacement. A complete B cell assessment for these patients is ongoing. Conclusions. B cell transgene expression is obtained after lentiviral vector-mediated GT in WAS patients and is associated with improved B cell lymphopoiesis. A correct B cell phenotype is observed in two patients who did not receive rituximab prior GT. The question whether this is related to the treatment will need a longer follow-up to be answered. Patients undergoing mismatched allogeneic HSCT present a higher frequency of complications. Although a higher proportion of these patients discontinued IvIg replacement, B cell reconstitution is not optimal. Analysis of patients in particular with mixed chimerism will provide important information in the setting of GT. The analysis of B cell reconstitution after GT and mismatched allogeneic HSCT deserves particular attention in the assessment of immunological reconstitution. Disclosures No relevant conflicts of interest to declare.

Introduction Ataxia-telangiectasia (A-T) is a rare autosomal recessive disorder associated with mutations in the ATMgene and characterized by cerebellar ataxia, telangiectasia, immune defect, and a high incidence of lymphoid and solid cancers. We conducted a retrospective study of the patients with AT enrolled in the registry of the French National Reference Center for Primary Immune Deficiencies, in order to describe the incidence, subtypes, and outcomes of cancer and mainly of lymphoproliferative diseases (LPD) occurring in AT. Most of the LPD of this study were centrally reviewed by 2 expert hematopathologists. Patients & Results Sixty nine patients with cancers were identified among the 279 patients with AT of our cohort. Eight patients developed carcinomas, 8 acute leukemias, 3 T-cell prolymphocytic leukemias and 50 developed lymphomas. Among the lymphomas, 12 were classical Hodgkin's lymphomas (cHL), and 38 high-grade non-Hodgkin lymphomas (NHL, 26 of B-cell type, 4 of T-cell type, and 8 not phenotyped). We obtained a centralized histopathology review in 31 cases classified by pathology reports as cHL (n=6) and high-grade NHL (n=25). Cases were reviewed according to the WHO classification by H&E staining and immunohistochemistry. The presence of EBV was analyzed using antibodies to LMP and in situ hybridization for EBER. Concordance between the diagnosis established on pathology reports and the centralized review was excellent. All 6 cases of cHL were confirmed by the pathology review. The 25 cases initially diagnosed as high-grade NHL based on pathology reports fell into several WHO classification categories. Six corresponded to Burkitt's lymphomas (BL) and 12 to diffuse large B-cell lymphomas (DLBCL). Among the latter, 10 could be further classified according to cell-of-origin by the Hans algorithm as germinal center (GC, 2) and non-GC (8). Seven cases displayed polymorphic histological features reminiscent of post-transplant lymphoproliferative disorders (LPD), 5 polymorphic B cell LPD (pLPD), 1 with features of infectious mononucleosis (IM), another with features of plasmacytic hyperplasia LPD. EBV could be evaluated in 28 cases. All 6 cHL, 4 out of 11 DLBCL, all 5 pLPD, and the case of IM-like LPD were EBV positive by LMP and/or EBER staining. The 5 cases of BL that were evaluated were all EBV negative. Median age at diagnosis was 7.8 years [range 3 – 24], 14.9 [5.8 – 17.1], 12.2 [5.4 – 29] and 11 [6.3 – 17.7] for pLPD, cHL, BL and DLBCL respectively (p=ns). Median survival after diagnosis of lymphoma was 35, 8.6, 6 and 8 months for pLPD, cHL, BL and DLBCL respectively (p=ns). ATM mutation analysis was available for 20 cases (8 hypomorphic mutations, 12 loss-of-function mutations). There were no differences in age at diagnosis of lymphoma or survival according to the ATM mutation class or the EBV status. Conclusion B-cell malignancies including cHL and B-cell NHL are the most frequent malignancies in A-T and can be further classified as DLBCL, BL and cases with polymorphic features resembling post-transplant LPD. EBV seems to be associated with all cHL, approximately 50% of DLBCL and polymorphic LPD, but not with BL. The majority of DLBCL are non-GC type by immunohistochemistry. On this series of 31 patients, ATM mutation type was not associated with differences in type of lymphoma or outcome. Disclosures No relevant conflicts of interest to declare.

Wiskott-Aldrich syndrome (WAS) is a rare, X-chromosomal recessive disorder which is caused by mutations in the WAS gene and characterized by eczema, immunodeficiency and microthrombocytopenia (Thrasher and Burns, Nat Rev Immunol 2010). Interestingly, WAS protein (WASp)-deficient mice have normal-sized platelets and thus the molecular link between WAS mutations and its central hallmark microthrombocytopenia remains elusive. Profilin1 (Pfn1) is a key actin-regulating protein that, besides actin, interacts with phosphoinositides and multiple proline-rich proteins including the WAS protein (WASp)/WASp-interacting protein (WIP) complex (Witke, Trends Cell Biol 2004; Ramesh et al., Proc Natl Acad Sci USA, 1997). Interestingly, similar to WAS patients, mice with Pfn1-null megakaryocytes/platelets suffered from microthrombocytopenia. We identified accelerated platelet clearance by macrophages and pre-mature platelet release into the bone marrow compartment as the major cause of the reduced platelet count in Pfn1-deficient mice. Both, platelets from Pfn1-null mice and WAS patients contained abnormally organized and hyperstable microtubules. We next tested, if increased microtubule stability could account for the reduced size of Pfn1-deficient platelets. Treatment of control platelets with microtubule stabilizing toxins, such as the histone-deacetylase inhibitor trichostatin A (TSA) or taxol resulted in a decreased platelet size. This finding indicates that increased microtubule stability could account for the reduced platelet size in Pfn1-deficient mice but also in WAS patients. Based on these results we speculate that WASp might modulate Pfn1 function and dysregulation of this interaction leads to increased stability and altered organization of microtubules. In support of this, the subcellular localization of Pfn1 was altered in platelets of three WAS patients. Together, these results reveal an unexpected function of Pfn1 as a regulator of microtubule organization and point to a previously unrecognized mechanism underlying the platelet formation defect in WAS patients. Disclosures No relevant conflicts of interest to declare.

Wiskott-Aldrich syndrome (WAS) is an X-linked primary immune deficiency (PID) characterized by persistent thrombocytopenia, eczema and immunodeficiency. It has been suggested that these patients had an increased risk of lymphoproliferative diseases (LPD). We conducted a retrospective study in order to describe LPD occurring in patients with WAS/XLT (X Linked Thrombocytopenia with WAS gene mutation) enrolled in the French national registry for PIDs. Post- hematopoietic stem cell transplantation (HSCT) LPD were excluded. Methodology of the French National Registry for PIDs has been previously described (Clin. Immunol, 2010, ASH 2009 abstract#23950). Eight patients (4%) with LPD were identified among the 197 patients of our cohort. All patients had a WAS and presented first symptoms of WAS before the age of one year. One patient developed a LPD before the clinical diagnosis of WAS. All patients for whom histological charts were available (6/8) developed a B-cell LPD. Three of them had diffuse large B-cell lymphomas and three patients had polymorphic B-cell LPD associated with EBV and without detection of clonal IGHV rearrangement. The median age of cancer diagnosis was 18.3 years (range: 2.0-50.7). All LPD were disseminated diseases, mostly with a central nervous system involvement (4/6 patients). All patients received intensive chemotherapy, except one patient with an EBV-associated LPD who only received rituximab. Three patients obtained a complete remission (CR), two patients had a stable disease (SD) and the last one progressed on therapy. Four patients, of whom two were in CR and one in SD, received an allogeneic HSCT during the year following the diagnosis of LPD. Two patients received peripheral blood-derived stem cells and the two other patients received bone marrow-derived stem cells. There were three matched unrelated donor (MUD) and one haplotype-mismatched family donor, with no ex vivo graft manipulation. Three of these four patients were long-term survivors after LPD (2.7, 7.7 and 9.8 years). The median life expectancy for the entire cohort is 19.1 years (range: 7.8-52.0). Three patients, two of which have received an HSCT, are still alive 2.4, 2.7 and 9.8 years after the cancer onset. The median overall survival among the five remaining patients after diagnosis of LPD was 0.5 years (from 0.3 to 7.7 years). Additional details on genetic, clinical characteristics and a centralized histopathology review are currently being studied and will be presented. In conclusion, the occurrence of LPD is less frequent than expected, may occur only in patients with WAS phenotype rather than XLT. As it impairs the prognosis of patients, HSCT could be a therapeutic option for these patients, even in partial remission of LPD. Disclosures No relevant conflicts of interest to declare.

Familial hemophagocytic lymphohistiocytosis (FHL) is the genetic form of hemophagocytic lymphohistiocytosis with an autosomal recessive form of inheritance and early onset. FHL is characterized by prolonged fever, hepatosplenomegaly and pancytopenia. Type 3 of FHL (FHL3) which accounts for 30-35 % of all FHL patients, results from mutations in UNC13D gene encoding Munc13-4 protein. Munc13-4 controls fusion of lytic granules with the plasma membrane in cytotoxic lymphocytes and its defect leads to impaired cytotoxic activity in T and NK lymphocytes. The only curative method for FHL3 is allogenic hematopoietic stem cell (HSC) transplantation. For those patients without compatible bone marrow donor, gene therapy could represent a therapeutic option. Our study is based on a comparative analysis to investigate the efficacy and safety of stem cell and T-cell gene therapy for FHL3. To this end we have generated SIN-lentiviral constructs expressing Munc13-4 and used them to produce either VSVG or T-cell specific pseudotyped lentiviral vectors. We also could obtain functionally mature T-cells in vitro, derived from umbilical cord blood HSCs which respond to TCR stimulation and show cytotoxic effect. Using these approaches, first we demonstrated that our SIN-lentiviral constructs are able to transduce efficiently human T-cells and HSCs. We used then these vectors to complement the FHL3 patient’s cells. Transduction of FHL3 CD8 effector cells restored their cytotoxic function that was comparable to that of control cells. In addition we noted that the overexpression of Munc 13-4 in normal human HSCs didn’t alter in vitro differentiation of these cells towards T-cells. The effect of this overexpression on B-cells and myeloid differentiation is currently under investigation. These preliminary results will be followed by ex vivo gene transfer experiments in Munc13-4 deficient “Jinx” mice to further investigate the functional restoration as well as toxic effects. This strategy, if approved, could offer a safe therapeutic method not only for FHL3 patients but also for other genetic or acquired dysfunctions of T-lymphocytes. Disclosures: No relevant conflicts of interest to declare.

Introduction Chronic granulomatous disease (CGD) is a rare inherited disorder due to a defect in NADPH oxidase, resulting in recurrent, life-threatening invasive infections and granulomatous inflammatory disorders. Although CGD is diagnosed mostly in early childhood, its prognosis has now much improved, allowing a majority of patients to reach adulthood. Very few studies have focused on the long-term outcome of adult CGD patients. Objective To study the clinical course and sequelae at various time points (age 16, 20, 30 and beyond) of CGD patients, diagnosed before 16 years of age. Method A one-year (May 2012 to May 2013) French national retrospective study of CGD patients, diagnosed before the age of 16 years, and who had reached adulthood (defined as above 16 years of age) by the time of data collection. CGD patients were screened through the registry of the French national reference center of primary immune deficiencies (CEREDIH), and data were retrieved by reviewing medical charts and collected in a pre-defined case-report form. Results Eighty CGD patients (71 male (88.7%), 59 X-linked (73.7%), with a median NBT level of 0 [range:0; 15]) were included in the study. Median ages at diagnosis and last follow-up were 2.52 years [range: 0; 15.87] and 23.9 years [range: 16.61; 59.89], respectively. Seventeen patients (21%) were older than 30 years at time of last follow-up. Seven patients (8.8%) had undergone a hematopoietic stem-cell transplantation (HSCT). A total of 553 infections requiring hospital care (382 before age 16, and 171 thereafter), occurred among all patients during follow-up. The most common sites of infection were: pulmonary (31% of total infections, involving 77.5% patients), suppurative adenitis (24% of infections, 75% of patients), and cutaneous (16.2% of infections, 60% of patients). Aspergillus spp. (17%) and Staphylococcus aureus (10.7%) were the most common pathogens. These characteristics (sites and pathogens involved), as well as the annual frequency of infections, did not vary, when compared before and after age 16. When considering granulomatous events, a total of 224 inflammatory flares, mainly digestive (50%), pulmonary (16.7%) and urologic (10.3%), occurred among 71/80 (88.8%) patients. Thirty autoimmune events (mainly discoid lupus erythematosus) also occurred among 14/80 patients (17.2%). The median age of the first inflammatory event (12.5 years [range: 0.25; 44.2]) was much higher than that of the first serious infectious event (0.97 years [range: 0; 23.9]) (figure 1). The annual frequency of inflammatory events did not however significantly increase after age 16. Concerning the long-term consequences of such repeated infectious and steroid-treated inflammatory events, the main sequelae in CGD adults were a small adult median height and weight (167.5cm [range: 138; 185] and 56 kg [range: 35; 90] at age 20), as well as mild chronic restrictive respiratory failure (26.7% of chronic dyspnoea at the age of 30 years). At the age of 16 years, only 58% of patients were in high school. After 30 years, 9/13 (69%) patients were working, and 2 had had children. Ten patients died during adulthood at a median age of 23.6 years [range: 18.2; 45.4], most of them of infectious causes. Discussion & Conclusion Adult CGD patients display similar characteristics and rates of severe infections as during their childhood. As CGD patients grow older, inflammatory flares also become a major concern, because of an older age of appearance. The high rate of handicap that these repeated infectious and inflammatory events entail in adult CGD patients, now becomes a matter of medical and social considerations. A careful follow-up is thus recommended in specialized centers. Finally, HSCT and gene therapy should be more systematically considered in order to try to avoid long-term complications, which are responsible for major disabilities. Disclosures: No relevant conflicts of interest to declare.

Abstract 4350 Introduction: Transplantation of T cell depleted (TCD) HSC transplantation has been associated with:1) an increased risk of infectious complications due to a very late immune reconstitution, 2) a non negligible risk of Graft Versus Host Disease (GVHD) requiring immunosuppressive therapy, and 3) an increased risk of graft rejection. It has been demonstrated that GVHD in murine models is mostly mediated by naïve T cells. Memory T cells have a reduced capacity to induce GVHD while preserving the anti-infectious capacity (Anderson BE et al., 2003). Removing CD45RA cells from donor lymphocytes could reduce infectious complications without induction of GVHD. This procedure was evaluated in two patients presenting multiple infections and treated with mismatch HSC transplantation. Methods: Post transplant immune reconstitution has been compared between two groups. Group 1: 7 patients (1 ostepetrosis, 1 Fanconi anemia and 5 Severe Combined Immuno Deficiency) transplanted with TCD HSC (age: 3 months-11 years, sex ratio F/M: 4/3). Group 2: 2 patients (1 ORAI1 deficiency and 1 MHC class II deficiency) transplanted with TCD HSC and CD45RA depleted cells of the CD34 negative fraction (age: 8 and 23 months, 1 female and 1 male). All patients had myeloablative conditioning regimen. CD34+ cell selection and CD45RA cell depletion procedures were performed using the Clini Macs system (Miltenyi Biotec). Group 1 received a median of 15.3 × 106CD34+ cells/kg with less than 5000 T lymphocytes/kg. Group 2 received respectively 8.8 and 12.3×106 CD34+ cells/kg with less than 5000 T lymphocytes/kg in HSC transplant and 0.9 and 9.2×106/kg CD45RO+ T cells. The thresholds of 100 CD4+ T lymphocytes and 50 CD8+ T lymphocytes per microliter at three months post transplantation, shown to allow sufficient protection against infectious complications (Hakki et al. 2003), were used in our analysis. Results: No significant difference in GVHD incidence was shown between the two groups since only 2/7 patients presented moderate GVHD in group 1 and no GHVD in group 2. Engrafment for both kind of pathology in group 2 was also remarkable Immune reconstitution of CD4+ and CD8+ T lymphocytes was earlier in group 2 as at one month we detected CD4+ T lymphocytes (430 and 24/μl) and CD8+ T lymphocytes (520 and 40/μl) respectively for patient 1 and 2. Whereas in group 1 no T lymphocytes were detected before two months post transplant. The number of CD4+ and CD8+ T lymphocytes at three months post transplantation was considerably increased in group 2 (CD4+: 609 and 190/μl; CD8+: 2088 and 95/μl) versus group 1 (CD4+: 14/μl; CD8+: 0.4/μl). Patient 1 in group 2 presented CMV reactivation at day 10 post transplant (87650 copies/ml, threshold 500) and was able to clear this infection at day 37 concomitantly to an increased CMV tetramer positive cells percentage (Tetramers at day 37/tetramers at day 10: 433 fold increase). Conclusion: The two patients treated with T-cell depleted haematopoietic stem cells (HSC) transplantation and add back of CD45RA negative DLI showed good engraftment, earlier and enhanced immune reconstitution without GVHD. Moreover, one patient developed specific and efficient anti-CMV response probably due to an expansion of the injected CD45RO T cells. These interesting preliminary results should be confirmed by a clinical trial. Disclosures: No relevant conflicts of interest to declare.

Abstract 4484 Hematopoietic stem cell transplantation (HSCT) is the treatment for an increasing number of inherited diseases. Graft rejection and acute Graft Versus Host Disease (GVHD) are known to be the two major complications of this procedure. A high frequency of graft rejection is observed particularly in patients with inflammatory conditions associated with congenital metabolic diseases, IFN-gR1 deficiency, familial hemophagocytic lymphohistiocytosis. GVHD results from immunological attack on target recipient organs (skin, liver and gut) by donor allogeneic T cells that are transferred along with the allograft. A better understanding of the patients' inflammatory environment in the course of HSCT may allow for the establishment of predictive markers for the occurrence of engraftment or GVHD and the improvement of conditioning regimens and post-transplant immunosuppressive therapy. Methods: All pediatric patients treated in the Department of Immuno-Hematology at the Necker Hospital who received allogeneic HSCT after full intensity conditioning regimen for nonmalignant disorders including inherited immunodeficiencies, metabolic diseases or hemoglobinopathies are eligible for inclusion. Plasma samples are collected before conditioning (day-15), at the time of transplant (day 0), at day+15 and day+30 post-HSCT. Validated markers of GVHD (Elafin, Reg3α, and ST2) as well as pro-inflammatory, anti-inflammatory, and angiogenic cytokines were analyzed, respectively, using sequential enzyme-linked immunosorbent assays and Luminex technology, which enables the determination of large numbers of cytokines in very small amounts of childrens' plasma. Engraftment was assessed on the presence of full donor chimerism, GVHD upon clinical, biological and histopathological data. Results: From April 2011 to March 2012, 15 patients were included (8 males and 7 females with an age ranging from 4 months to 9 years). Five patients presented with severe combined immunodeficiencies, three with chronic granulomatous disease, five with metabolic diseases (three Hurler and two osteopetrosis), one with congenital aplastic anemia and one with sickle cell diseaseConditioning regimen consisted of Busulfan/Fludarabin/ATG for ten patients, Busulfan/Fludarabin/Thiotepa/ATG for four patients and Busulfan/Cyclophosphamid/ATG in one. Donors were matched unrelated (n=6), 4 matched related (n=4), haplo-identical (n=4), and with intrafamilial mismatched donor (n=1). Acute graft rejection was observed in 2 of 15 patients and sustained engraftment in 13 of 15. Acute GVHD was observed in 6 of 15 patient occurring between day+10 and day+45 [grade 1 (n=1), grade 3 (n=3) and grade 4 (n=2)]. At day+30, we found significantly higher plasma concentrations of IFNγ, TNFα, ST2, and VEGF in patients with GVHD as compared to patients without GVHD. TNFα was the only cytokine for which the plasma concentrations was already significantly higher at day+15 in patients with GVHD versus patients without GVHD. No statistically significant differences in plasma concentrations of IL-4, IL-6, TGFβ, IL-7, IL-8, IL-12, IL-13 and IL-17 were observed. The cytokine that appeared to differentiate patients with GVHD and patients without GVHD the most was IFN-α2 which had plasma concentrations that were consistently and significantly higher in patients without GVHD as compared to patients with GVHD from day-15 to day+15. Conclusion: These results confirm the Th1 associated profile of acute GVHD and the importance of endothelial dysfunction in GVHD, as suggested by increased concentrations of ST2 and VEGF in patients with GVHD. The potential forIFN-α2 as a predictive marker of GVHD in our population needs further confirmation through additional inclusions. A larger population is also needed to determine if a specific cytokine milieu is associated with other common HSCT complications seen in our population such as graft rejection and vascular complications such as sinusoidal obstructive syndrome of the liver and pulmonary arterial hypertension. Disclosures: No relevant conflicts of interest to declare.

Abstract 5092 Background The fact that monogenic interleukin (IL)-10 and IL-10 receptor deficiencies cause very early-onset, severe inflammatory bowel disease demonstrates the IL-10 pathway's crucial role in preventing microbiota-driven gut inflammation. However, no other severe complications of IL-10/IL-10R deficiencies have been reported to date. Methods A cohort of six patients with IL-10/IL-10R deficiency was retrospectively surveyed for phenotypic expression. The identification of a number of cases of lymphoma prompted an in-depth characterization of available biopsy material, with immunohistochemical staining, cytogenetic studies and gene expression profiling. Results Four patients (all with a complete IL-10R2 deficiency) had developed B cell non-Hodgkin's lymphoma between the ages of 5 and 6 years. Cytogenetic and IgH clonality analyses suggested that one of the patients developed at least 3 distinct lymphomas. The patients' tumors had the characteristics of diffuse large B cell lymphomas and contained monoclonal, Epstein-Barr-virus-negative germinal center B cells. Nuclear expression of the NF-κB factor c-REL was detected in all of the six lymphomas tested. Conclusions IL-10R deficiency is associated with a high risk of developing a B cell lymphoma with an unusual phenotype. Our results highlight an unexpected role of the IL-10R pathway in the control of lymphomagenesis. Disclosures: No relevant conflicts of interest to declare.

Abstract 1057 Background: Primary immunodeficiencies (PID) are rare congenital disorders involving defects of the immune system. Aside from infectious complications, patients are at increased risk of malignant complications, which represent a leading cause of mortality in this context. The pathophysiology underlying malignant complications, especially lymphoid malignancies, in PID is not fully understood. The molecular mechansims of PID, that often involve lymphoid developent pathways, may also play a role in oncogenesis. A better understanding of the epidemiology of malignancies in PID may provide important insights in oncogenesis, particularly in lympomagenesis. Material and methods: French National Reference Center for Primary Immune Deficiencies (CEREDIH) has registered 4632 patients with PID as of July 2012. T-cell immunoficiencies and B-cell immodificencies reprensent 35.8% and 46.1% respectively. Patients with Ataxia-Telangiectasia and Severe Congenital Neutropenia were excluded frome the present analysis as they represent a more homogeneous group in terms of molecular pathophysiology and have been described elsewhere. T-cell immunodeficiencies comprise Severe combined immudoficiencies, Combined immunodeficiencies, other well defined T-cell immunoficiencies (including Wiskott-Aldrich Syndrome), and diseases of immune regulation (including X-linked lymphoproliferative disease and Autoimmune lymphoproliferative syndrome). B-cell immunodeficiencies include Agammaglobulinemia, Common Variable Immunodeficiency, Unspecified primary hypogammaglobulinemia, Selective IgA deficiency, Hyper-IgM symdrome and IgG subclass deficiency. Diagnostic class of PID, Age at diagnosis of PID, age at diagnosis of neoplastic complication, type of neoplasia, and survival were retrospectively colloected from the medical files. Non-melanomatous skin cancers and lymphoproliferative disorders occuring after allogeneic stem cell tranplantation were excluded from the analysis. Results: 4632 patients with PID were analyzed. Two hundred and sixty seven patients developed 276 cancers (incidence 5.8%). One hundred and fifty seven patients developed lymphoid malignancies and 78 patients developed solid tumors (56.4% vs. 28.3% respectively). Compared to patients with B-cell PID, patients with T-cell PID had lower age at diagnosis of PID (5.5 [0–12.4] vs. 1.3–78]). Lymphoid malignancies, mainly high grade lymphomas were more prevalent in T-cell PID and PID diagnosed at a younger age (median age at diagnosis of PID for patients with lymphoid malignancies vs. solid tumors, 5.2 yr [0–85] and 37.5 [0–80] respectively, p Discussion: PID bear a high risk of malignancies (5.8%). Solid tumors are observed mainly in B-cell PID and are diagnosed at an older age. Lymphoid malignancies are observed mainly in T-cell PID and B-cell PID diagnosed at a younger age, underlying a possible pathophysiological link between T-cell PID and a subset of B-cell PID. Disclosures: No relevant conflicts of interest to declare.

Abstract SCI-21 There are a variety of primary T cell immunodeficiencies that can impair T cell differentiation or T cell activation. The latter include CD38δ deficiency, ZAP70 deficiency, Ca++ influx deficiency (ORAI1 and Stim1 deficiencies), and ITK deficiency as well. A new T cell activation deficiency as observed in a patient with defective T cell receptor triggered T cell activation and low CD4 T cell counts will be reported. A remarkable and quasi constant feature shared by all those T cell activation defects is the occurrence of autoimmune diseases, mostly related to autoantibodies, and inflammation such as colitis or panniculitis. Several mechanisms can account for these findings that include defective regulatory T cell development or function, defective negative selection impaired intrinsic feedback mechanism as well as non TCR-mediated T cell activation ultimately leading to proinflammatory cytokines release and autoantibody production by B cells. Another new form of primary T cell immunodeficiency with autosomal recessive inheritance observed in four patients from two families will be described. It is characterized by defective survival of naïve T cells. There again, autoimmunity appeared to be a significant component of the phenotype. Collectively, these results indicate that further insight into the role of key molecules in T cell activation/survival is provided by the analysis of new primary immunodeficiency phenotypes. In addition, the occurrence of autoimmunity in these settings stresses on one hand the role of T cells in the control of reactivity to self and, on the other hand, should be considered in the therapeutic strategy of these conditions. Disclosures: No relevant conflicts of interest to declare.