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Allogeneic hematopoietic stem cell transplantation (HSCT) is the gold standard curative therapy for infants and children with many inborn errors of immunity (IEI), but adolescents and adults with IEI are rarely referred for transplant. Lack of published HSCT outcome data outside small, single-center studies and perceived high risk of transplant-related mortality have delayed the adoption of HSCT for IEI patients presenting or developing significant organ damage later in life. This large retrospective, multicenter HSCT outcome study reports on 329 IEI patients (age range, 15-62.5 years at HSCT). Patients underwent first HSCT between 2000 and 2019. Primary endpoints were overall survival (OS) and event-free survival (EFS). We also evaluated the influence of IEI-subgroup and IEI-specific risk factors at HSCT, including infections, bronchiectasis, colitis, malignancy, inflammatory lung disease, splenectomy, hepatic dysfunction, and systemic immunosuppression. At a median follow-up of 44.3 months, the estimated OS at 1 and 5 years post-HSCT for all patients was 78% and 71%, and EFS was 65% and 62%, respectively, with low rates of severe acute (8%) or extensive chronic (7%) graft-versus-host disease. On univariate analysis, OS and EFS were inferior in patients with primary antibody deficiency, bronchiectasis, prior splenectomy, hepatic comorbidity, and higher hematopoietic cell transplant comorbidity index scores. On multivariable analysis, EFS was inferior in those with a higher number of IEI-associated complications. Neither age nor donor had a significant effect on OS or EFS. We have identified age-independent risk factors for adverse outcome, providing much needed evidence to identify which patients are most likely to benefit from HSCT.

Data on stem cell transplantation (SCT) for Diamond–Blackfan Anemia (DBA) is limited. We studied patients transplanted for DBA and registered in the EBMT database. Between 1985 and 2016, 106 DBA patients (median age, 6.8 years) underwent hematopoietic stem cell transplantation from matched-sibling donors (57%), unrelated donors (36%), or other related donors (7%), using marrow (68%), peripheral blood stem cells (20%), both marrow and peripheral blood stem cells (1%), or cord blood (11%). The cumulative incidence of engraftment was 86% (80% to 93%), and neutrophil recovery and platelet recovery were achieved on day +18 (range, 16 to 20) and +36 (range, 32 to 43), respectively. Three-year overall survival and event-free survival were 84% (77% to 91%) and 81% (74% to 89%), respectively. Older patients were significantly more likely to die (hazard ratio, 1.4; 95% confidence interval, 1.06 to 1.23; P< .001). Outcomes were similar between sibling compared to unrelated-donor transplants. The incidence of acute grades II to IV of graft-versus-host disease (GVHD) was 30% (21% to 39%), and the incidence of extensive chronic GVHD was 15% (7% to 22%). This study shows that SCT may represent an alternative therapeutic option for transfusion-dependent younger patients.

In the absence of an HLA-matched donor, the best treatment for acquired aplastic anemia patients refractory to immunosuppression is unclear. We collected and analyzed data from all acquired aplastic anemia patients who underwent a haploidentical transplantation with posttransplant cyclophosphamide in Europe from 2011 to 2017 (n= 33). The cumulative incidence of neutrophil engraftment was 67% (CI95%: 51–83%) at D +28 and was unaffected by age group, stem cell source, ATG use, or Baltimore conditioning regimen. The cumulative incidence of grades II–III acute GvHD was 23% at D +100, and limited chronic GvHD was 10% (0–20) at 2 years, without cases of grade IV acute or extensive chronic GvHD. Two-year overall survival was 78% (64–93), and 2-year graft-versus-host disease-free survival was 63% (46–81). In univariate analysis, the 2-year OS was higher among patients who received the Baltimore conditioning regimen (93% (81–100) versus 64% (41–87), p= 0.03), whereas age group, stem cell source, and ATG use had no effect. Our results using unmanipulated haploidentical transplantation and posttransplant cyclophosphamide for treating refractory AA patients are encouraging, but warrant confirmation in a prospective study with a larger number of patients and longer follow-up.

AML SCT-BFM 2007 was the first hematopoietic stem cell transplantation (HCT) trial in Germany to comply with the European Clinical Trials Directive, and aimed to standardize pediatric HCT for acute myeloid leukemia (AML) across centers in Germany, Austria, and the Czech Republic. Children with high-risk features and a good early response achieving a complete first remission (CR-1) and those in CR-2 after a first relapse were stratified to receive HCT from a matched donor after myeloablative conditioning consisting of busulfan, cyclophosphamide, and melphalan. Four-year EFS and OS were 61 and 70%. Cumulative incidence of relapse (CIR) was 22%. TRM was 15% and correlated with age reaching 9% (SE 3%) in children younger than 12 years and 31% (SE 9%) in older children and adolescents. Children with poorly responding primary disease or relapse were allocated to receive early HCT after a cytoreductive regimen with fludarabine, amsacrine, and cytarabine, followed by reduced intensity conditioning and prophylactic donor lymphocyte infusions. Four-year EFS and OS were 49 and 53%. CIR was 38% and TRM 11%. For patients with primary poor response disease, early use of RIC HCT followed by prophylactic DLI can induce long-term remissions in more than 50% (EFS 46% (SE 9%)).

Langerhans cell histiocytosis (LCH) is a MAPK pathway‐driven disease characterized by the accumulation of CD1a+langerin+cells of unknown origin. We have previously reported that the Notch signaling pathway is active in LCH lesions and that the Notch ligand Jagged2 (JAG2) induces CD1a and langerin expression in monocytes in vitro. Here we show that Notch signaling induces monocytes to acquire an LCH gene signature and that Notch inhibition suppresses the LCH phenotype. In contrast, while also CD1c+dendritic cells or IL‐4‐stimulated CD14+monocytes acquire CD1a and langerin positivity in culture, their gene expression profiles and surface phenotypes are more different from primary LCH cells. We propose a model where CD14+monocytes serve as LCH cell precursor and JAG2‐mediated activation of the Notch signaling pathway initiates a differentiation of monocytes toward LCH cells in selected niches and thereby contributes to LCH pathogenesis. This study aims to identify the cell of origin of Langerhans Cell Histiocytosis and the molecular mechanisms of its pathogenesis.

Background

Developmental tumors in children and young adults carry few genetic alterations, yet they have diverse clinical presentation. Focusing on Ewing sarcoma, we sought to establish the prevalence and characteristics of epigenetic heterogeneity in genetically homogeneous cancers. We performed genome-scale DNA methylation sequencing for a large cohort of Ewing sarcoma tumors and analyzed epigenetic heterogeneity on three levels: between cancers, between tumors, and within tumors. We observed consistent DNA hypomethylation at enhancers regulated by the disease-defining EWS-FLI1 fusion protein, thus establishing epigenomic enhancer reprogramming as a ubiquitous and characteristic feature of Ewing sarcoma. DNA methylation differences between tumors identified a continuous disease spectrum underlying Ewing sarcoma, which reflected the strength of an EWS-FLI1 regulatory signature and a continuum between mesenchymal and stem cell signatures. There was substantial epigenetic heterogeneity within tumors, particularly in patients with metastatic disease. In summary, our study provides a comprehensive assessment of epigenetic heterogeneity in Ewing sarcoma and thereby highlights the importance of considering nongenetic aspects of tumor heterogeneity in the context of cancer biology and personalized medicine.

•Single-agent vemurafenib leads to a rapid and sustained clinical response in severe multisystem LCH but does not eradicate the disease.•Longitudinal assessment of BRAFV600E during treatment shows that clinical remission can occur despite significant amounts of mutated BRAF.

Reduced-intensity conditioning has improved survival after hematopoietic stem cell transplantation (HSCT) for hemophagocytic lymphohistiocytosis (HLH) at the cost of more frequent mixed chimerism. The minimum level of donor chimerism (DC) required to prevent HLH reactivation in humans remains to be determined. In a multicenter retrospective study, 103 patients transplanted for hereditary HLH (2000-2013) and DC permanently or transiently <75% (overall, CD3+, CD56+) were analyzed regarding DC, specific immunologic function, occurrence of systemic reactivations (≥5/8 HLH criteria), partial systemic flares (<5 criteria and HLH-directed treatment), isolated central nervous system reactivations, and management. Recurrence was reported in 18 patients (systemic reactivation n = 11, partial flare n = 3, isolated central nervous system reactivation n = 4). Ten events occurred during profound immune suppression before day 180 (median DC, 10%; range, 1-100%; CD3+ if available, otherwise overall DC), which renders a differentiation between secondary post-HSCT HLH and HLH related to the genetic defect difficult. Eight events occurred between 0.5 and 6.7 years post-HSCT (median DC, 13%; range, 0-30%). In 5 patients, overall and lineage-specific DC were ≤10% for >6 months (median, 5.1; range, 1.1-10 years) without reactivation. A second HSCT was performed in 18 patients (median, DC 4%; range, 0-19%). Death from reactivation occurred in 4 patients (22% of recurrences). Six patients died of transplant complications following a second HSCT (33% of second HSCT). We conclude that a DC >20%-30% is protective against late reactivation. Lower levels do not, however, inescapably result in recurrences. The decision for or against second HSCT must be based on a thorough risk assessment.

Reduced-intensity conditioning has improved survival after hematopoietic stem cell transplantation (HSCT) for hemophagocytic lymphohistiocytosis (HLH) at the cost of more frequent mixed chimerism. The minimum level of donor chimerism (DC) required to prevent HLH reactivation in humans remains to be determined. In a multicenter retrospective study, 103 patients transplanted for hereditary HLH (2000-2013) and DC permanently or transiently <75% (overall, CD3+, CD56+) were analyzed regarding DC, specific immunologic function, occurrence of systemic reactivations (≥5/8 HLH criteria), partial systemic flares (<5 criteria and HLH-directed treatment), isolated central nervous system reactivations, and management. Recurrence was reported in 18 patients (systemic reactivation n = 11, partial flare n = 3, isolated central nervous system reactivation n = 4). Ten events occurred during profound immune suppression before day 180 (median DC, 10%; range, 1-100%; CD3+if available, otherwise overall DC), which renders a differentiation between secondary post-HSCT HLH and HLH related to the genetic defect difficult. Eight events occurred between 0.5 and 6.7 years post-HSCT (median DC, 13%; range, 0-30%). In 5 patients, overall and lineage-specific DC were ≤10% for >6 months (median, 5.1; range, 1.1-10 years) without reactivation. A second HSCT was performed in 18 patients (median, DC 4%; range, 0-19%). Death from reactivation occurred in 4 patients (22% of recurrences). Six patients died of transplant complications following a second HSCT (33% of second HSCT). We conclude that a DC >20%-30% is protective against late reactivation. Lower levels do not, however, inescapably result in recurrences. The decision for or against second HSCT must be based on a thorough risk assessment.

While survival rates in paediatric acute lymphoblastic leukaemia (ALL) nowadays exceed 90%, systemic ALL relapse, especially after haemopoietic stem cell transplantation (HSCT), is associated with a poor outcome. As there is currently no standardized treatment for this situation, individualized treatment is often pursued. Exemplified by two clinical scenarios, the aim of this article is to highlight the challenge for treating physicians to find a customized treatment strategy integrating the role of conventional chemotherapy, immunotherapeutic approaches and second allogeneic HSCT. Case 1 describes a 2-year-old girl with an early isolated bone marrow relapse of an infant KMT2A-rearranged B-cell precursor ALL after allogeneic HSCT. After bridging chemotherapy and lymphodepleting chemotherapy, chimeric antigen receptor (CAR) T-cells (tisagenlecleucel) were administered for remission induction, followed by a second HSCT from the 9/10 human leukocyte antigen (HLA)-matched mother. Case 2 describes a 16-year-old girl with a late, isolated bone marrow relapse of B-cell precursor ALL after allogeneic HSCT who experienced severe treatment toxicities including stage IV renal insufficiency. After dose-reduced bridging chemotherapy, CAR T-cells (tisagenlecleucel) were administered for remission induction despite a CD19-clone without prior lymphodepletion due to enhanced persisting toxicity. This was followed by a second allogeneic HSCT from the haploidentical mother. While patient 2 relapsed around Day + 180 after the second HSCT, patient 1 is still in complete remission >360 days after the second HSCT. Both cases demonstrate the challenges associated with systemic ALL relapse after first allogeneic HSCT, including chemotherapy-resistant disease and persisting organ damage inflicted by previous therapy. Immunotherapeutic approaches, such as CAR T-cells, can induce remission and enable a second allogeneic HSCT. However, optimal therapy for systemic ALL relapse after first HSCT remains to be defined.

Malignant peripheral nerve sheath tumors (MPNSTs) constitute <2 of soft tissue neoplasms in children and display a wide histologic spectrum including low-grade and epithelioid variants, although most are high-grade spindle cell sarcomas. Here, we describe an unusual case of a large retroperitoneal epithelioid MPNST diagnosed in a 7-year-old girl without family history or clinical features of neurofibromatosis type 1. The patient was treated by repeated surgical interventions, polychemotherapy, autologous stem cell transplantation, and irradiation therapy. Over the years, she developed multiple disseminated abdominal recurrences but is currently alive with very slowly progressing disseminated intra-abdominal disease 18 years from initial diagnosis. Histologically, the tumor was composed of medium-sized polygonal and ovoid-to-spindled cells set within a copious myxoid matrix with a prominent reticular and microcystic pattern reminiscent of the recently described reticularmicrocystic schwannoma. Immunohistochemistry revealed strong and diffuse expression of S100, CD56, CD57, collagen IV, and neuron-specific enolase, with negativity for perineurial cell markers (claudin-1, epithelial membrane antigen, and glucose transporter-1) and other lineage-specific mesenchymal and epithelial antigens. This unusual variant of low-grade MPNST must be differentiated from a variety of other entities, in particular benign perineurioma, myxoid neurofibroma, and benign reticularmicrocystic schwannoma. Confinement of the recurrent disease to the abdominal cavity emphasizes the necessity of primary curative wide excision of this highly recurring but nonmetastasizing low-grade neoplasm.

Primary B-cell disorders comprise a heterogeneous group of inherited immunodeficiencies, often associated with autoimmunity causing significant morbidity. The underlying genetic etiology remains elusive in the majority of patients. In this study, we investigated a patient from a consanguineous family suffering from recurrent infections and severe lupuslike autoimmunity. Immunophenotyping revealed progressive decrease of CD19+B cells, a defective class switch indicated by low numbers of IgM- and IgG-memory B cells, as well as increased numbers of CD21lowB cells. Combined homozygosity mapping and exome sequencing identified a biallelic splice-site mutation in protein C kinaseδ(PRKCD), causing the absence of the corresponding protein product. Consequently, phosphorylation of myristoylated alanine-rich C kinase substrate was decreased, and mRNA levels of nuclear factor interleukin (IL)-6 and IL-6 were increased. Our study uncovers human PRKCD deficiency as a novel cause of common variable immunodeficiency-like B-cell deficiency with severe autoimmunity.

Primary B-cell disorders comprise a heterogeneous group of inherited immunodeficiencies, often associated with autoimmunity causing significant morbidity. The underlying genetic etiology remains elusive in the majority of patients. In this study, we investigated a patient from a consanguineous family suffering from recurrent infections and severe lupuslike autoimmunity. Immunophenotyping revealed progressive decrease of CD19+ B cells, a defective class switch indicated by low numbers of IgM- and IgG-memory B cells, as well as increased numbers of CD21low B cells. Combined homozygosity mapping and exome sequencing identified a biallelic splice-site mutation in protein C kinaseδ (PRKCD), causing the absence of the corresponding protein product. Consequently, phosphorylation of myristoylated alanine-rich C kinase substrate was decreased, and mRNA levels of nuclear factor interleukin (IL)-6 and IL-6 were increased. Our study uncovers human PRKCD deficiency as a novel cause of common variable immunodeficiency-like B-cell deficiency with severe autoimmunity.

Previous studies have shown that children with acute myeloid leukemia (AML) who developed mixed chimerism (MC) were at high risk for relapse after allogeneic stem-cell transplantation (allo-SCT). We investigated the feasibility of intensified preemptive immunotherapy in children receiving allo-SCT for AML. Eighty-four children were registered in our trial from May 2005 to April 2009; of these, 71 fulfilled the inclusion criteria and were treated according to the study protocol. Serial and semiquantitative analyses of posttransplantation chimerism were performed. Defined immunotherapy approaches were considered in MC patients. Continuous complete chimerism (CC) was observed in 51 of 71 patients. MC was detected in 20 patients and was followed by immunotherapy in 13. Six of 13 MC patients returned to CC without toxicity and remained in long-term remission. Overall, the probability of event-free survival (pEFS) was 66% (95% confidence interval [95% CI] = 53%-76%) for all patients and 46% (95% CI = 19%-70%) in MC patients with intervention; however, this number increased to 71% (95% CI = 26%-92%) in 7 of 13 MC patients on immunotherapy who were in remission at the time of transplantation. All MC patients without intervention relapsed. These results suggest that MC is a prognostic factor for impending relapse in childhood AML, and that preemptive immunotherapy may improve the outcome in defined high-risk patients after transplantation.

Current evidence suggests that maturing dendritic cells (DCs) acquire a migratory phenotype to induce T cell responses in lymph nodes or a proinflammatory phenotype to condition the microenvironment at peripheral sites. We show that the interplay of PGE2and IFN‐γ generates a more complex pattern of mixed DC phenotypes in response to TLR stimulation. DCs activated by the TLR ligand R‐848 in the presence of IFN‐γ and PGE2produced high levels of IL‐12p70 and IL‐23, started migration toward CCL19 within only 10 h, and still continued to secrete IL‐12p70 without further restimulation following the migration step. The accelerated onset of migration was a result of PGE2and was associated with reduced plastic adherence and lower amounts of activated CD29. In contrast, IFN‐γ by itself enhanced cell adhesion and strongly hindered CCR7‐mediated migration in the absence of PGE2. This suggests a new role for IFN‐γ in the direct regulation of DC migration through enhanced cell adhesion, perhaps to support the development of T cell effector functions at peripheral sites. Together, our data are relevant to the development of DC vaccines, as they demonstrate the existence of dual‐functional DCs, which as a result of the simultaneous effects of PGE2and IFN‐γ, can migrate rapidly toward lymph node chemokines and carry with them a wave of primary cytokines.

Following allogeneic hematopoietic stem cell transplantation (alloHSCT), children are at risk of life-threatening pneumococcal infections. Whereas vaccination with polysaccharide vaccines fails to elicit protective immunity in most alloHSC transplant recipients, pneumococcal conjugate vaccines may effectively prevent invasive disease by eliciting T-cell–dependent antibody responses. Here, we report safety and immunogenicity in 53 children immunized with a regimen of 3 consecutive doses of a heptavalent pneumococcal conjugate vaccine (7vPCV) in monthly intervals starting 6 to 9 months after alloHSCT. Immunization was well tolerated with no vaccine-related serious adverse events. Serologic response rates evaluable in 43 patients ranged from 41.9% to 86.0% and 58.1% to 93.0% after 2 and 3 vaccinations, respectively, with 55.8% and 74.4% of patients achieving protective antibody levels to all 7 vaccine serotypes. Our study provides the first evidence that vaccination with 7vPCV is safe and elicits protective antipneumococcal antibody responses in pediatric recipients of related or unrelated donor alloHSC transplants within the first year following transplantation. This trial was registered at www.clinicaltrials.gov as NCT00169728.

Following allogeneic hematopoietic stem cell transplantation (alloHSCT), children are at risk of life-threatening pneumococcal infections. Whereas vaccination with polysaccharide vaccines fails to elicit protective immunity in most alloHSC transplant recipients, pneumococcal conjugate vaccines may effectively prevent invasive disease by eliciting T-cell–dependent antibody responses. Here, we report safety and immunogenicity in 53 children immunized with a regimen of 3 consecutive doses of a heptavalent pneumococcal conjugate vaccine (7vPCV) in monthly intervals starting 6 to 9 months after alloHSCT. Immunization was well tolerated with no vaccine-related serious adverse events. Serologic response rates evaluable in 43 patients ranged from 41.9% to 86.0% and 58.1% to 93.0% after 2 and 3 vaccinations, respectively, with 55.8% and 74.4% of patients achieving protective antibody levels to all 7 vaccine serotypes. Our study provides the first evidence that vaccination with 7vPCV is safe and elicits protective antipneumococcal antibody responses in pediatric recipients of related or unrelated donor alloHSC transplants within the first year following transplantation. This trial was registered at www.clinicaltrials.govas NCT00169728.

Ewing's sarcoma is the second most common primary bone malignancy in childhood and adolescence. We present a standardized interdisciplinary treatment protocol according to the EURO-E.W.I.N.G. 99 study, applied in the treatment of a 7-year-old patient with localized Ewing's sarcoma of the left mandible. After six blocks of VIDE (vincristine/ifosfamide/doxorubicin/etoposide) chemotherapy and stem cells rescue, intensity modulated external radiation with 48.6 Gy and subsequent high dose therapy with busulphan-melphalan were administered. Tumor resection and immediate bony reconstruction was performed using a microvascular fibula graft 10 weeks after radiation. Because of the effective neoadjuvant treatment, no extensive soft tissue resection was necessary. Healing of the osteosynthesis was uneventful. No local or systemic recurrence and no signs of significant facial deformity were found after 12 month follow-up. The presented case underlines the requirement for multidisciplinary protocols involving radiologists, pathologists, oncologists, radiation oncologists, and surgeons for accurate diagnosis and appropriate therapy. To preserve cosmetics and function within the craniofacial area after tumor resection in children, microvascular reconstructive procedures can be successfully performed with a vascularized fibular graft.

Pearson bone marrow-pancreas syndrome (PS) is a rare, usually fatal mitochondrial disorder involving the hematopoietic system in early infancy. Due to the diversity of clinical symptoms, the diagnosis can be difficult. The authors describe a boy with severe hypoplastic anemia in whom extensive clinical, biochemical, and morphologic findings led to the diagnosis of PS, and molecular analysis revealed a novel deletion of mitochondrial DNA from nucleotide position 10.371 to 14.607.

In large-scale pediatric chemo- and radiotherapy trials a proportion of patients as high as 10–15% is usually reported as having severe treatment related toxicity occasionally resulting in toxic death. Little is known on the underlying predisposition of the individual child. Several hereditary disorders including immunodeficiency (ID) syndromes or repair disorders, Ataxia Telangiectasia (AT), and Nijmegen breakage syndrome (NBS) were associated with an elevated risk for severe treatment related toxicity. This report involves the case of a 7-year-old boy with medulloblastoma who suffered from remarkably severe side effects during and after postoperative radio- and chemotherapy. Several months following craniospinal radiation with a total dose of 36 Gy, late normal tissue side effects were observed within the treated volume. Eighteen months after initiation of treatment the patient died due to protracted cardiopulmonary failure. To quantify the intrinsic radiation sensitivity, lymphoblastoid cells were used to examine chromosomal aberrations by fluorescence in situ hybridization detecting between two to ninefold higher chromosomal breakage rates in comparison to cells of average cancer patients. Skin fibroblasts showed in the clonogenic survival assays a twofold increased sensitivity. Western blotting demonstrated a typical lack of Nbs1. PCR-SSCP analysis followed by direct sequencing of positive samples revealed a homozygous truncating mutation of the NBS1 gene (657del5). This case highlights that severe treatment related complications in pediatric cancer patients may be the result of increased intrinsic radio- and chemosensitivity due to NBS, AT, and other ID syndromes. It is suggested to exclude such conditions in all patients with anthropometric parameters below the 3rd centile and other signs suggestive for repair disorders or ID syndromes. Med Pediatr Oncol 2003;41:44–48. © 2003 Wiley-Liss, Inc.

Langerhans cell histiocytosis (LCH) is a histiocytic disease, characterized by the lesional accumulation of dendritic Langerhans cells together with T cells and eosinophils. The cause of this disease is unknown. Langerhans cells are bone marrow-derived dendritic cells (DCs), which can develop from CD34⁺ hematopoietic progenitor cells as well as from monocytes. To test whether LCH patients have a general functional defect present in cells of their DC lineage, we generated immature DCs by culturing monocytes from nine patients with single- or multisystem LCH with GM-CSF and IL-4, and analyzed their phenotype and function before and after an in vitro maturation stimulus. Immature DCs were analyzed for their phenotype and cytokine production, DCs matured in response to TNF-α plus PGE2 were analyzed for their phenotype, their stimulatory capacity in MLR, cell aggregation, and activation-induced apoptosis. In summary, no difference was found between both immature as well as mature DCs generated from patients and controls regarding the expression of CD1a, CD80, CD86, MHC class I, and MCH class II antigens. Similarly, no difference was found regarding IL-10, -12, and TNF-α production, as well as regarding cell aggregation and apoptosis in response to external stimuli. The absence of gross functional abnormalities in DCs generated from monocytes from patients with LCH makes the existence of a severe functional defect affecting all cells of the DC lineage in these patients unlikely. Med Pediatr Oncol 2002;39:181–186. © 2002 Wiley-Liss, Inc.

Impaired T-cell function after T-cell– depleting (TCD) therapy has been hypothesized to be related to a transient predominance of extrathymically expanding memory T cells. To test whether after TCD therapy the naive T-helper cell population is functionally intact, the in vitro immune response of CD4+CD45RA+ (naive) and of CD4+CD45RA− (memory) cells to polyclonal mitogens (immobilized anti-CD3, phytohemagglutinin) was analyzed by flow cytometry in 22 pediatric patients after high-dose chemotherapy (including 5 after autologous and 5 after allogeneic stem cell support). At 1 to 3 months after TCD therapy, patient samples showing decreased lymphoproliferative responses also showed a reduced induction of the early activation marker CD69 by CD4+ T cells from 4 to 72 hours after stimulation even when supplemented with exogenous interleukin-2. This defect affected CD4+CD45RA− cells, but, strikingly, also CD4+CD45RA+ cells, including samples in which CD4+CD45RA+ cells were more than 90/μL, thus indicating ongoing thymopoiesis. Histogram analyses showed the median peak channel of CD69 in control CD4+CD45RA+cells rising 98-fold (median) but only 28-fold in patient cells (P < .0001). Apoptosis as detected by annexin V staining was increased in resting patient CD4+ T cells (25% versus 6%) and also affected CD4+CD45RA+ cells (12% versus 5%, P < .01). When peripheral blood mononuclear cells (PBMCs) were enriched for T cells, stimulatory responses of CD4+ cells and of CD4+CD45RA+ cells markedly improved. Thus, after TCD therapy suppressor factors contained in the non–T-cell fraction of PBMCs may affect T-helper cells irrespective of their naive or memory phenotype thus extending T-cell dysfunction to the presumably thymus-dependently regenerated T cells.

Impaired T-cell function after T-cell– depleting (TCD) therapy has been hypothesized to be related to a transient predominance of extrathymically expanding memory T cells. To test whether after TCD therapy the naive T-helper cell population is functionally intact, the in vitro immune response of CD4+CD45RA+(naive) and of CD4+CD45RA−(memory) cells to polyclonal mitogens (immobilized anti-CD3, phytohemagglutinin) was analyzed by flow cytometry in 22 pediatric patients after high-dose chemotherapy (including 5 after autologous and 5 after allogeneic stem cell support). At 1 to 3 months after TCD therapy, patient samples showing decreased lymphoproliferative responses also showed a reduced induction of the early activation marker CD69 by CD4+T cells from 4 to 72 hours after stimulation even when supplemented with exogenous interleukin-2. This defect affected CD4+CD45RA−cells, but, strikingly, also CD4+CD45RA+cells, including samples in which CD4+CD45RA+cells were more than 90/μL, thus indicating ongoing thymopoiesis. Histogram analyses showed the median peak channel of CD69 in control CD4+CD45RA+cells rising 98-fold (median) but only 28-fold in patient cells (P< .0001). Apoptosis as detected by annexin V staining was increased in resting patient CD4+T cells (25% versus 6%) and also affected CD4+CD45RA+cells (12% versus 5%, P< .01). When peripheral blood mononuclear cells (PBMCs) were enriched for T cells, stimulatory responses of CD4+cells and of CD4+CD45RA+cells markedly improved. Thus, after TCD therapy suppressor factors contained in the non–T-cell fraction of PBMCs may affect T-helper cells irrespective of their naive or memory phenotype thus extending T-cell dysfunction to the presumably thymus-dependently regenerated T cells.

Both type I interferons (IFNs) as well as lipopolysaccharide (LPS) individually compromise selected monocytic or dendritic cell (DC) functions. This study investigates the influence of these agents on the differentiation and the regulation of cell death of monocyte-derived DCs generated in the presence of granulocyte-macrophage colony-stimulating factor plus interleukin-4 (IL-4). It is reported that excessive apoptosis occurred rapidly in monocyte-derived DC cultures, if IFN-α or IFN-β was added in combination with LPS or lipoteichoic acid (LTA). The small fraction of cells surviving in such cultures displayed a mature DC phenotype with expression of CD83, CD80, and CD86. IL-10 was found in the supernatants of monocyte-derived DC cultures, if supplemented with LPS or IFN-α plus LPS but not in control cultures. When monocyte-derived DCs were generated in the presence of IFN-α without LPS, these cells displayed an immature DC phenotype with a reduction of cell recovery but no overt apoptosis. However, the addition of LPS, LTA, LPS plus IFN-γ, or tumor necrosis factor α (TNF-α) plus prostaglandin E2 to such cells again resulted in the rapid induction of apoptosis in the majority of cells, together with a reduced production of IL-12 p70 and TNF-α. Together, these data indicate an exquisite sensitivity of monocyte-derived DCs to activation-induced cell death if generated in the presence of IFN-α, indicating the existence of an important mechanism of immunosuppression caused by IFN-α–inducing agents, such as viral or bacterial stimuli.

Both type I interferons (IFNs) as well as lipopolysaccharide (LPS) individually compromise selected monocytic or dendritic cell (DC) functions. This study investigates the influence of these agents on the differentiation and the regulation of cell death of monocyte-derived DCs generated in the presence of granulocyte-macrophage colony-stimulating factor plus interleukin-4 (IL-4). It is reported that excessive apoptosis occurred rapidly in monocyte-derived DC cultures, if IFN-α or IFN-β was added in combination with LPS or lipoteichoic acid (LTA). The small fraction of cells surviving in such cultures displayed a mature DC phenotype with expression of CD83, CD80, and CD86. IL-10 was found in the supernatants of monocyte-derived DC cultures, if supplemented with LPS or IFN-α plus LPS but not in control cultures. When monocyte-derived DCs were generated in the presence of IFN-α without LPS, these cells displayed an immature DC phenotype with a reduction of cell recovery but no overt apoptosis. However, the addition of LPS, LTA, LPS plus IFN-γ, or tumor necrosis factor α (TNF-α) plus prostaglandin E2 to such cells again resulted in the rapid induction of apoptosis in the majority of cells, together with a reduced production of IL-12 p70 and TNF-α. Together, these data indicate an exquisite sensitivity of monocyte-derived DCs to activation-induced cell death if generated in the presence of IFN-α, indicating the existence of an important mechanism of immunosuppression caused by IFN-α–inducing agents, such as viral or bacterial stimuli.

Experimental gene transfer and viral infections can result in the accumulation of unintegrated DNA in target cells. The effects of such accumulation on target cell metabolism have not been directly studied. The experiments reported in this paper show that transfection of cloned retroviral long-terminal-repeat (LTR) DNA, or of a variety of eukaryotic promoters, into proliferating HeLa cells results in rapid, sequence-specific, and dose-dependent cell death. Plasmids containing the Rous sarcoma virus LTR or the human immunodeficiency virus LTR cloned in pUC-related plasmids are 5 to 10 times more toxic than pUC19. The demonstrated sensitivity of eukaryotic cells to exogenously introduced DNA has important implications for the interpretation of gene transfer experiments and may be relevant to the pathogenic mechanisms in the course of retroviral infections such as AIDS.

Ten monoclonal antibodies to human leukocyte subsets that had previously been shown to lyse their respective target cells in the presence of rabbit serum as complement source were evaluated for their cytolytic capacity with human complement. Four of the ten were lytic with human complement. All were of IgM type.

Monoclonal antibodies recognizing CD27, a member of the nerve growth factor receptor family, have been observed to enhance or inhibit PHA- or CD3 mAb-stimulated T cell proliferation. In this study, we investigate the effects of CD27 stimulation on the proliferation and cytokine production of T cells stimulated simultaneously through CD3, CD2, or CD28. Here we report that simultaneous crosslinking of CD27 plus CD28 results in T cell proliferation and in the production of IL-2, IL-4, IL-10, and IFN-γ. CD27 plus CD28 stimulation thus introduces a novel Ag-independent pathway of T cell activation. We further show that all major T cell subsets (CD4+, CD8+, CD4+CD45RA+, or CD4+CD45RO+T cells) respond to CD27 plus CD28-mediated costimulation. Synergistic effects on T cell stimulation are also found when CD27 is crosslinked on cells stimulated simultaneously through CD3 or CD2. In further experiments we show that crosslinking of CD27 elevates cytoplasmic free Ca2+levels. Finally, both the CD3 plus CD27 and the CD28 plus CD27-stimulated T cell proliferation is sensitive to inhibition by CsA. Taken together, these data emphasize the importance of CD27 stimulation in the context of simultaneously received signals through CD3, CD2 or, most importantly, through CD28. Furthermore, signaling through CD27 appears to involve Ca2+-dependent mechanisms sensitive to CsA.

The two-signal model of T-cell activation postulates that T lymphocytes require at least two distinct signals for activation. This model has been established with bulk cultures of T cells in which T-cell-T-cell interaction can occur, possibly delivering further unrecognized costimulatory signals. The signal requirements of single T cells for the induction of clonal cell growth or the transcription of cytokines would best be studied in a cell cloning system in the absence of feeder cells; however, such an experimental system has not been reported so far. In this study, we report the long-term cloning of human resting peripheral blood CD4+CD45RO–T cells under feeder cell-free conditions in response to CD3 and CD28 stimulation in the presence of exogenous interleukin-2 (IL-2). Cloning efficiency ranged from 40% to 60% depending on the presence of additional cytokines IL-1 and IL-6. Single-cell polymerase chain reaction showed that transcription of IL-2 occurred in cells stimulated through CD3 plus CD28 alone. T cells grown in response to CD3 plus CD28 plus IL-2 stimulation produced both IL-4 and irrterferon-γ (IFN-γ) on restimulation (ThO cells) and could be functionally differentiated into Th1- or Th2-type cells by the addition of IFN-γor IL-4, respectively, during cell cloning. These data show on the single-cell level a two-signal model of T-cell activation for the transcription of IL-2. In addition, these experiments show that IFN-γand IL-4 exert their T-cell-drffererttiating effects directly on the T cell without any further need for antigen-presenting cells. Together, our experiments show the feasibility of a defined long-term clonal cell culture system to study the growth and differentiation of human T lymphocytes.

We investigated the production of cytokines by highly purified T helper cells from B-cell chronic lymphocytic leukemia (B-CLL) patients stimulated by different activation pathways, and we studied the influence of various accessory cell populations on the pattern of the secretion of cytokines, including interleukin (IU-2, IL-4, interferon-γ (IFN-γ), and IL-10. Neither a qualitative nor a quantitative difference in cytokine production and proliferative capacity was observed in CLL-derived purified T cells compared with normal individuals, when T cells were stimulated by different pathways, including CD3, CD2, and costimulation with CD28. Addition of autologous accessory cells (aAC), however, dramatically influenced the cytokine pattern of normal versus B-CLL-de-rived T cells. CLL cells as aAC caused a marked increase of IL-2, whereas IFN-γ was only slightly induced and IL-4 was not influenced. In contrast, in normal individuals addition of aAC, which predominantly consisted of monocytes, resulted in a significant increase of IFN-γ and a reduction of IL-4 secretion. IL-2 production was inhibited by higher concentrations of aAC The increased stimulation of IL-2 production by CLL cells was not specific to the leukemic cell population, as purified B cells from normal individuals had the same effect. On the other hand, purified monocytes from CLL patients and controls both induced IFN-γ production and inhibited IL-4 secretion. After antigen-specific stimulation with tetanus toxoid, cytokine secretion was influenced by the type of aAC in a similar pattern. We conclude that T helper cells derived from patients with B-CLL are intrinsically normal and that the predominance of B cells as accessory cells in CLL significantly afters the immune function of T helper cells in vitro.

Kabuki syndrome is a rare condition characterized by distinct dysmorphic features and a broad spectrum of organ anomalies. Differentiating it from other syndromes can be difficult, particularly in patients with incomplete phenotypic manifestation. Recently, MLL2gene mutations were identified as the underlying genetic cause of Kabuki syndrome in the majority of cases.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

The authors describe a young boy with juvenile myelomonocytic leukemia (JMML) who relapsed 45 days after HLA and killer immunoglobulin-like receptor (KIR) mismatched unrelated donor bone marrow transplant (MMUD-BMT) and subsequently developed life-threatening graft-versus-host disease (GvHD). Treatment with 6-mercaptopurine (6-MP) appeared to control severe GvHD and possibly prevented recurrence of leukemic relapse.

Peffault De Latour: Alexion Pharmaceuticals, Inc.: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Amgen Inc.: Research Funding; Pfizer Inc.: Consultancy, Honoraria, Research Funding. Ganser:Novartis: Membership on an entity's Board of Directors or advisory committees. Risitano:Pfizer Inc.: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Alexion Pharmaceuticals, Inc.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Alnylam Pharmaceuticals, Inc.: Consultancy, Honoraria, Research Funding; Ra Pharmaceuticals, Inc.: Consultancy, Honoraria, Research Funding; Amyndas Pharmaceuticals: Consultancy; Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.

Bloor: Janssen: Research Funding; AbbVie: Research Funding. Ganser:Novartis: Membership on an entity's Board of Directors or advisory committees. Tilly:Celgene: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; BMS: Honoraria; Astra-Zeneca: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees. Russell:Pfizer: Consultancy, Honoraria, Speakers Bureau; Jazz Pharma: Speakers Bureau; Daiichi Sankyo: Consultancy. Kerre:Celyad: Consultancy; BMS: Consultancy; Celgene: Consultancy, Research Funding. Peffault De Latour:Novartis: Consultancy, Honoraria, Research Funding; Pfizer Inc.: Consultancy, Honoraria, Research Funding; Amgen Inc.: Research Funding; Alexion Pharmaceuticals, Inc.: Consultancy, Honoraria, Research Funding.

The outcome of patients with severe aplastic anemia (SAA) has greatly improved in recent years but is still poor for patients who failed or relapsed after immunosuppressive therapy (IST) and don't have a matched donor. Recent use of eltrombopag shows blood count improvements in 40% of cases, but most patients refractory to immunosuppressive therapy, are also unresponsive to eltrombopag. In this situation, hematopoietic stem cell transplantation (HSCT) using alternative donor sources (mismatched unrelated donors, cord blood, and haploidentical family donors) may be curative but are also associated with a high risk of morbidity and mortality. Moreover, ethnic minorities have limited access to an alternative donor, especially in the adult population. Haploidentical transplantation using post-transplant cyclophosphamide (Haplo-PTCy) has been shown to facilitate engraftment and shows GvHD rates comparable to those of matched sibling HSCT in hematologic malignancies. However, few papers have been published on Haplo-PTCy in the context of aplastic anemia.