Search

Hematopoietic stem cell transplantation and gene therapy are the only curative therapies for severe combined immunodeficiency (SCID). In patients lacking a matched donor, TCRαβ/CD19-depleted haploidentical family donor transplant (TCRαβ-HaploSCT) is a promising strategy. Conditioned transplant in SCID correlates to better myeloid chimerism and reduced immunoglobulin dependency. We studied transplant outcome in SCID infants according to donor type, specifically TCRαβ-HaploSCT, and conditioning, through retrospective cohort analysis of 52 consecutive infants with SCID transplanted between 2013 and 2020. Median age at transplant was 5.1 months (range, 0.8–16.6). Donors were TCRαβ-HaploSCT (n = 16, 31.4%), matched family donor (MFD, n = 15, 29.4%), matched unrelated donor (MUD, n = 9, 17.6%), and matched unrelated cord blood (CB, n = 11, 21.6%). Forty-one (80%) received fludarabine/treosulfan-based conditioning, 3 (6%) had alemtuzumab only, and 7 (14%) received unconditioned infusions. For conditioned transplants (n = 41), 3-year overall survival was 91% (95% confidence interval, 52–99%) for TCRαβ-HaploSCT, 80% (41–98%) for MFD, 87% (36–98%) for MUD, and 89% (43–98%) for CB (p = 0.89). Cumulative incidence of grade II–IV acute graft-versus-host disease was 11% (2–79%) after TCRαβ-HaploSCT, 0 after MFD, 29% (7–100%) after MUD, and 11% (2–79%) after CB (p = 0.10). 9/10 patients who received alemtuzumab-only or unconditioned transplants survived. Myeloid chimerism was higher following conditioning (median 47%, range 0–100%) versus unconditioned transplant (median 3%, 0–9%) (p n = 29/36, 81% vs n = 4/9, 54%) (p

Hematopoietic stem cell transplantation and gene therapy are the only curative therapies for severe combined immunodeficiency (SCID). In patients lacking a matched donor, TCRαβ/CD19-depleted haploidentical family donor transplant (TCRαβ-HaploSCT) is a promising strategy. Conditioned transplant in SCID correlates to better myeloid chimerism and reduced immunoglobulin dependency. We studied transplant outcome in SCID infants according to donor type, specifically TCRαβ-HaploSCT, and conditioning, through retrospective cohort analysis of 52 consecutive infants with SCID transplanted between 2013 and 2020. Median age at transplant was 5.1 months (range, 0.8-16.6). Donors were TCRαβ-HaploSCT (n = 16, 31.4%), matched family donor (MFD, n = 15, 29.4%), matched unrelated donor (MUD, n = 9, 17.6%), and matched unrelated cord blood (CB, n = 11, 21.6%). Forty-one (80%) received fludarabine/treosulfan-based conditioning, 3 (6%) had alemtuzumab only, and 7 (14%) received unconditioned infusions. For conditioned transplants (n = 41), 3-year overall survival was 91% (95% confidence interval, 52-99%) for TCRαβ-HaploSCT, 80% (41-98%) for MFD, 87% (36-98%) for MUD, and 89% (43-98%) for CB (p = 0.89). Cumulative incidence of grade II-IV acute graft-versus-host disease was 11% (2-79%) after TCRαβ-HaploSCT, 0 after MFD, 29% (7-100%) after MUD, and 11% (2-79%) after CB (p = 0.10). 9/10 patients who received alemtuzumab-only or unconditioned transplants survived. Myeloid chimerism was higher following conditioning (median 47%, range 0-100%) versus unconditioned transplant (median 3%, 0-9%) (p 0.001), as was the proportion of immunoglobulin-free long-term survivors (n = 29/36, 81% vs n = 4/9, 54%) (p 0.001). TCRαβ-HaploSCT has comparable outcome to MUD and is a promising alternative donor strategy for infants with SCID lacking MFD. This study confirms that conditioned transplant offers better myeloid chimerism and immunoglobulin freedom in long-term survivors.

Mutations in the coiled-coil and DNA-binding domains of STAT1 lead to delayed STAT1 dephosphorylation and subsequently gain-of-function. The associated clinical phenotype is broad and can include chronic mucocutaneous candidiasis (CMC) and/or combined immunodeficiency (CID). We report a case of CMC/CID in a 10-year-old boy due to a novel mutation in the small ubiquitin molecule (SUMO) consensus site at the C-terminal region of STAT1 leading to gain-of-function by impaired sumoylation. Immunodysregulatory features of disease improved after Janus kinase inhibitor (jakinib) treatment. Functional testing after treatment confirmed reversal of the STAT1 hyper-phosphorylation and downstream transcriptional activity. IL-17 and IL-22 production was, however, not restored with jakinib therapy (ruxolitinib), and the patient remained susceptible to opportunistic infection. In conclusion, a mutation in the SUMO consensus site of STAT1 can lead to gain-of-function that is reversible with jakinib treatment. However, full immunocompetence was not restored, suggesting that this treatment strategy might serve well as a bridge to definitive therapy such as hematopoietic stem cell transplant rather than a long-term treatment option.

PURPOSE\ud \ud To investigate the clinical and functional aspects of MST1 (STK4) deficiency in a profoundly CD4-lymphopenic kindred with a novel homozygous nonsense mutation in STK4. Although recent studies have described the cellular effects of murine Mst1 deficiency, the phenotype of MST1-deficient human lymphocytes has yet to be fully explored. Patient lymphocytes were therefore investigated in the context of current knowledge of murine Mst1 deficiency.\ud \ud METHODS\ud \ud Genetic etiology was identified by whole exome sequencing of genomic DNA from two siblings, combined with linkage analysis in the wider family. MST1 protein expression was assessed by immunoblotting. The ability of patient lymphocytes to adhere to ICAM-1 under flow conditions was measured, and transwell assays were used to assess chemotaxis. Chemokine receptor expression was examined by flow cytometry and receptor signalling by immunoblotting.\ud \ud RESULTS\ud \ud A homozygous nonsense mutation in STK4 (c.442C > T, p.Arg148Stop) was found in the patients, leading to a lack of MST1 protein expression. Patient leukocytes exhibited deficient chemotaxis after stimulation with CXCL11, despite preserved expression of CXCR3. Patient lymphocytes were also unable to bind effectively to immobilised ICAM-1 under flow conditions, in keeping with a failure to develop high affinity binding.\ud \ud CONCLUSION\ud \ud The observed abnormalities of adhesion and migration imply a profound trafficking defect among human MST1-deficient lymphocytes. By analogy with murine Mst1 deficiency and other defects of leucocyte trafficking, this is likely to contribute to immunodeficiency by impairing key aspects of T-cell development and function such as positive selection in the thymus, thymic egress and immune synapse formation in the periphery.

To the Editor, In 2011, Moratto et al. [1]. identified age at haematopoietic stem cell transplantation (HSCT) as a risk modifier for complications inWiskott-Aldrich syndrome (WAS); of note, complications appear to be 1.5 times more likely in children transplanted at ages 2–5, compared to younger than 2 (RR = 1.53; CI, 0.90–2.58; P = 0.130). This reinforces the importance of prompt recognition, diagnosis and assessment for HSCT in patients with suspected WAS. We evaluated the presenting features in boys with WAS mutations transplanted at the Great North Childrens’ Hospital, Newcastle-upon-Tyne between 1989 and 2015 in order to identify any delay in diagnosis and causative factors, including misdiagnosis, and clarify the role of mean platelet volume in making a diagnosis of WAS. We sought to identify key discriminating diagnostic features in order to aid timely diagnosis and transplantation of these patients. Data was collected retrospectively from written and electronic medical records of 20 boys with WAS mutations, for which all families had given prior written consent. Information regarding date and nature of symptom onset, time elapsed until diagnosis, mean platelet volume at presentation, age at transplantation and outcome were recorded in an anonymised spreadsheet. Symptomatology was coded as one or more of the following: infectious and immunological, including autoimmunity; eczema; bruising and petechiae; and bleeding. No differentiation was made between WAS and XLT due to no significant difference in platelet counts, platelet size and bleeding episodes in these conditions. Median age at symptom onset was 2 months (birth – 9 months) and at diagnosis was 1 year (2 months – 14.1 years). Median interval between symptom onset and diagnosis was 8 months (2 weeks – 13.8 years). The most common presenting symptom was bleeding (13 reports, 65 %). The subsequent most common symptoms were bruising (11, 55 %); eczema and skin disease (9, 45 %) and immunological and infectious (7, 35 %). Initial documented impressions included nonaccidental injury [1], congenital cytomegalovirus infection [1] and suspected ITP [2]. The most common combination of symptoms at presentation was bruising with eczema, in 7 (35 %), bleeding and bruising, 5 (25 %); bleeding and eczema, 5 (25 %); bleeding and infective/immunological, 4 (20 %); bruising and infective or immunological, 4 (20 %), infective or immunological and eczema, 1 (5 %) patient. There was no documented family history of WAS or XLT. Eight patients (40 %) had a recorded mean platelet volume (MPV) following presentation to our unit. Median MPV was 4.85 fl (range: 3.6–21); only 3 patients had a volume < 5 fl (Fig. 1). One result was recorded as Blow^ and so was omitted from analysis. Our results show a lag between onset of symptoms and confirmed diagnosis of WAS of 8 months. A diagnostic delay in WAS (and other primary immunodeficiency disorders) of * Christo Tsilifis ctsilifis@gmail.com

Autosomal dominant Hyper IgE Syndrome (AD-HIES) is a primary immunodeficiency characterized by connective tissue, vascular and skeletal abnormalities [1], and due to mutations in the signal transducer and activator of transcription 3 (STAT3) gene [2, 3]. Treatment is largely supportive and includes prophylactic antibiotics and antifungal therapy, early treatment of infections, immunoglobulin, and in some cases, haematopoietic stem cell transplant (HSCT) [4, 5]. There is little published evidence-based research on the management of AD-HIES in paediatric patients, particularly in preventing parenchymal lung damage. A retrospective review of paediatric patients with ADHIES from the Great North Children’s Hospital, Newcastle upon Tyne, England and Our Lady’s Children’s Hospital, Dublin, Ireland, was performed to assess strategies in therapeutic management and clinical outcomes. Ten patients were included, five male (Table 1). One patient had a positive family history ofAD-HIES.Median age at diagnosis was 2.3 years (range 3 months – 13.6 years). Two patients underwent HSCT details were included up to the point of transplant. Median follow-up (excluding the patients who underwent HSCT) was 8.5 years. All received antibiotic prophylaxis, most commonly cotrimoxazole (n = 7), flucloxacillin (n =6) and azithromycin (n=6), with some patients trialled on more than one. To account for variable durations on antibiotic prophylaxis, the number of infections per patient-year was calculated with and without antibiotic prophylaxis. We were unable to quantify the number of infections for one patient (who had no clinical improvement on prophylaxis and went on to HSCT). For the remaining nine patients, the median duration on antibiotic prophylaxis was 5 years (range 2.8–16.2 years). Eight had a reduction in the number of infections per patient-year. The one patient who did not was reported to have improved clinically, but the duration on prophylaxis was only 2.8 years. Five patients received prophylactic antifungal therapy, three itraconazole and two voriconazole. Three (30 %) had pulmonary Aspergillus infections (two invasive infections, one colonising), diagnosed at a median age of 12.9 years, all with underlying parenchymal lung damage. These patients received no antifungal prophylaxis prior to detection of Aspergillus fumigatus. Three of 8 (37.5 %) patients with parenchymal lung damage developed fungal infections. All commenced antifungal prophylaxis after identification of Aspergillus fumigatus, following which no further pulmonary fungal infections occurred. Of the other patients who received prophylactic antifungal therapy, one had recurrent Candidiasis, the other patient had no history of fungal infections. Four (40 %) patients, previously treated with oral antibiotic prophylaxis, received immunoglobulin (IgG), most commonly because of poor pneumococcal antibody responses in combination with deteriorating clinical status. Median age at initiation was 8.8 years (range 2.6–14.4 years). All continued antibiotic prophylaxis whilst receiving IgG. Two had bronchiectasis, one prior to commencing IgG, with no progression following treatment. Three patients had no clinical improvement upon starting IgG therapy. Five (50 %) patients had bronchiectasis confirmed by thoracic computerised tomography, diagnosed at a median age of 9.6 years (range 6.6–12 years). In this group, median age at diagnosis of AD-HIES was 6.5 years (range 2–13.6 years) compared to 1 year in the group without bronchiectasis (range * Andrew R. Gennery a.r.gennery@ncl.ac.uk

To investigate the clinical and functional aspects of MST1 (STK4) deficiency in a profoundly CD4-lymphopenic kindred with a novel homozygous nonsense mutation in STK4. Although recent studies have described the cellular effects of murine Mst1 deficiency, the phenotype of MST1-deficient human lymphocytes has yet to be fully explored. Patient lymphocytes were therefore investigated in the context of current knowledge of murine Mst1 deficiency.Genetic etiology was identified by whole exome sequencing of genomic DNA from two siblings, combined with linkage analysis in the wider family. MST1 protein expression was assessed by immunoblotting. The ability of patient lymphocytes to adhere to ICAM-1 under flow conditions was measured, and transwell assays were used to assess chemotaxis. Chemokine receptor expression was examined by flow cytometry and receptor signalling by immunoblotting.A homozygous nonsense mutation in STK4 (c.442CT, p.Arg148Stop) was found in the patients, leading to a lack of MST1 protein expression. Patient leukocytes exhibited deficient chemotaxis after stimulation with CXCL11, despite preserved expression of CXCR3. Patient lymphocytes were also unable to bind effectively to immobilised ICAM-1 under flow conditions, in keeping with a failure to develop high affinity binding.The observed abnormalities of adhesion and migration imply a profound trafficking defect among human MST1-deficient lymphocytes. By analogy with murine Mst1 deficiency and other defects of leucocyte trafficking, this is likely to contribute to immunodeficiency by impairing key aspects of T-cell development and function such as positive selection in the thymus, thymic egress and immune synapse formation in the periphery.

We previously have demonstrated impaired pneumococcal polysaccharide IgG antibody responses in children immunosuppressed following cardiac transplantation in early childhood. We have further characterized the antibody defect. To further investigate the production of antibody, anti-pneumococcal polysaccharide (PPS) specific IgM, IgG, IgG subclasses, and IgA were measured in postvaccination sera by enzyme-linked immunosorbent assay. Two groups were studied: posttransplant children who made pneumococcal antibody in vivo following natural exposure or PPS immunization (R) and those with an impaired response (NR). There was no difference in IgM or IgA levels between R and NR. IgG and IgG2 levels were higher in R than NR (P = 0.002), even after adsorption of nonspecific common cell wall antigen antibody. Differences in anti-pneumococcal antibody levels suggest that immunoglobulin isotype switching from IgM to IgG and particularly IgG2 is impaired in patients immunosuppressed at a young age. These findings confirm data regarding the effect of immunosuppressive agents derived from animal models in humans.

Pneumococcal polysaccharide (PPS) antibody deficiency occurs in some children immunosuppressed following cardiac transplantation in early childhood. We studied lymphocyte subset populations in these children to identify patterns associated with antibody deficiency, particularly in CD21 + B cells. Lymphocyte surface markers CD3, CD4, CD8, CD19, and CD21 were measured on whole blood by FACS analysis in four patient groups: cardiac transplant patients who did and did not respond to PPS, nontransplanted cardiac patients, and normal controls. Absolute cell numbers were compared with age-related normal ranges. The proportion of children with values below the age-related 25th percentile in each group was compared. Normal controls had significantly more CD3+, CD8+, and CD19+ cells, even when age-related differences were accounted for. Control groups had significantly more CD19 cells than transplant patients and transplanted PPS responders and cardiac controls had more mature B cells (CD21+) than transplanted PPS nonresponders. PPS antibody deficiency following pediatric cardiac transplantation may be related to an immaturity in B cells due to immunosuppression commenced in early childhood.

Pneumococcal polysaccharide (PPS) antibody deficiency occurs in some children immunosuppressed following cardiac transplantation in early childhood. We studied lymphocyte subset populations in these children to identify patterns associated with antibody deficiency, particularly in CD21 + B cells. Lymphocyte surface markers CD3, CD4, CD8, CD19, and CD21 were measured on whole blood by FACS analysis in four patient groups: cardiac transplant patients who did and did not respond to PPS, nontransplanted cardiac patients, and normal controls. Absolute cell numbers were compared with age-related normal ranges. The proportion of children with values below the age-related 25th percentile in each group was compared. Normal controls had significantly more CD3+, CD8+, and CD19+ cells, even when age-related differences were accounted for. Control groups had significantly more CD19 cells than transplant patients and transplanted PPS responders and cardiac controls had more mature B cells (CD21+) than transplanted PPS nonresponders. PPS antibody deficiency following pediatric cardiac transplantation may be related to an immaturity in B cells due to immunosuppression commenced in early childhood.

We previously have demonstrated impaired pneumococcal polysaccharide IgG antibody responses in children immunosuppressed following cardiac transplantation in early childhood. We have further characterized the antibody defect. To further investigate the production of antibody, antipneumococcal polysaccharide (PPS) specific IgM, IgG, IgG subclasses, and IgA were measured in postvaccination sera by enzyme-linked immunosorbent assay. Two groups were studied: posttransplant children who made pneumococcal antibody in vivo following natural exposure or PPS immunization (R) and those with an impaired response (NR). There was no difference in IgM or IgA levels between R and NR. IgG and IgG2 levels were higher in R than NR (P = 0.002), even after adsorption of nonspecific common cell wall antigen antibody. Differences in anti-pneumococcal antibody levels suggest that immunoglobulin isotype switching from IgM to IgG and particularly IgG2 is impaired in patients immunosuppressed at a young age. These findings confirm data regarding the effect of immunosuppressive agents derived from animal models in humans.