Expanding the PRAAS spectrum: De novo mutations of immunoproteasome subunit ß-type 10 in six infants with SCID-Omenn syndrome.

Mutations in proteasome ß-subunits or their chaperone and regulatory proteins are associated with proteasome-associated autoinflammatory disorders (PRAAS). We studied six unrelated infants with three de novo heterozygous missense variants in PSMB10, encoding the proteasome ß2i-subunit. Individuals presented with T-B-NK± severe combined immunodeficiency (SCID) and clinical features suggestive of Omenn syndrome, including diarrhea, alopecia, and desquamating erythematous rash. Remaining T cells had limited T cell receptor repertoires, a skewed memory phenotype, and an elevated CD4/CD8 ratio. Bone marrow examination indicated severely impaired B cell maturation with limited V(D)J recombination. All infants received an allogeneic stem cell transplant and exhibited a variety of severe inflammatory complications thereafter, with 2 peri-transplant and 2 delayed deaths. The single long-term transplant survivor showed evidence for genetic rescue through revertant mosaicism overlapping the affected PSMB10 locus. The identified variants (c.166G>C [p.Asp56His] and c.601G>A/c.601G>C [p.Gly201Arg]) were predicted in silico to profoundly disrupt 20S immunoproteasome structure through impaired ß-ring/ß-ring interaction. Our identification of PSMB10 mutations as a cause of SCID-Omenn syndrome reinforces the connection between PRAAS-related diseases and SCID.

Outcome of Second Allogeneic HSCT for Patients with Inborn Errors of Immunity: Retrospective Study of 20 Years' Experience.

A significant complication of HSCT is graft failure, although few studies focus on this problem in patients with inborn errors of immunity (IE). We explored outcome of second HSCT for IEI by a retrospective, single-centre study between 2002 and 2022. Four hundred ninety-three patients underwent allogeneic HSCT for severe combined immunodeficiency (SCID; n = 113, 22.9%) or non-SCID IEI (n = 380, 77.1%). Thirty patients (6.0%) required second HSCT. Unconditioned infusion or no serotherapy at first HSCT was more common in patients who required second transplant. Median interval between first and second HSCT was 0.97 years (range: 0.19-8.60 years); a different donor was selected for second HSCT in 24/30 (80.0%) patients. Conditioning regimens for second HSCT were predominately treosulfan-based (with thiotepa: n = 18, 60.0%; without, n = 6, 20.0%). Patients received grafts from peripheral blood stem cell (n = 25, 83.3%) or bone marrow (n = 5, 16.7%) with median stem cell dose 9.5 × 106 CD34 + cells/kilogram (range: 1.4-32.3). Median follow-up was 1.92 years (0.22-16.0). Overall survival was 80.8% and event-free survival was 64.7%. Four patients died, two of early-transplant related complications, and two of late sepsis post-second HSCT. Three patients required third HSCT; all are alive with 100% donor chimerism. Cumulative incidence of acute graft-versus-host disease was 28.4%, (all grade I-II). Viral reactivation was seen in 13/30 (43.3%) patients, including HHV6 (n = 6), CMV (n = 4), and adenovirus (n = 2). At latest follow-up, 25/26 surviving patients have donor chimerism ≥ 90% and 16/25 (64.0%) have discontinued immunoglobulin replacement. Second HSCT offers IEI patients with graft failure curative treatment with good overall survival and immunological recovery.

Asymptomatic immunodeficiency-associated vaccine-derived poliovirus infections in two UK children.

Increasing detections of vaccine-derived poliovirus (VDPV) globally, including in countries previously declared polio free, is a public health emergency of international concern. Individuals with primary immunodeficiency (PID) can excrete polioviruses for prolonged periods, which could act as a source of cryptic transmission of viruses with potential to cause neurological disease. Here, we report on the detection of immunodeficiency-associated VDPVs (iVDPV) from two asymptomatic male PID children in the UK in 2019. The first child cleared poliovirus with increased doses of intravenous immunoglobulin, the second child following haematopoetic stem cell transplantation. We perform genetic and phenotypic characterisation of the infecting strains, demonstrating intra-host evolution and a neurovirulent phenotype in transgenic mice. Our findings highlight a pressing need to strengthen polio surveillance. Systematic collection of stool from asymptomatic PID patients who are at high risk for poliovirus excretion could improve the ability to detect and contain iVDPVs.

T-replete HLA-matched grafts vs T-depleted HLA-mismatched grafts in inborn errors of immunity.

Hematopoietic cell transplantation (HCT) has become standard-of-care for an increasing number of inborn errors of immunity (IEI). This report is the first to compare transplant outcomes according to T-cell-replete (ie, T-replete) HLA-matched grafts using alemtuzumab (n = 117) and T-cell-depleted (ie, T-depleted) HLA-mismatched grafts using T-cell receptor-αß (TCRαß)/CD19 depletion (n = 47) in children with IEI who underwent first HCT between 2014 and 2019. All patients received treosulfan-based conditioning except patients with DNA repair disorders. For T-replete grafts, the stem cell source was marrow in 25 (21%) patients, peripheral blood stem cell (PBSC) in 85 (73%), and cord blood in 7 (6%). TCRαß/CD19 depletion was performed on PBSCs from 45 haploidentical parental donors and 2 mismatched unrelated donors. The 3-year overall survival (OS) and event-free survival for the entire cohort were 85% (77%-90%) and 79% (69%-86%), respectively. Analysis according to age at transplant revealed a comparable 3-year OS between T-replete grafts (88%; 76%-94%) and T-depleted grafts (87%; 64%-96%) in younger patients (aged <5 years at HCT). For older patients (aged >5 years), the OS was significantly lower in T-depleted grafts (55%; 23%-78%) compared with T-replete grafts (87%; 68%-95%) (P = .03). Grade III to IV acute graft-versus-host disease was observed in 8% of T-replete marrow, 7% of T-replete PBSC, 14% of T-replete cord blood, and 2% of T-depleted PBSC (P = .73). Higher incidence of viremia (P < .001) and delayed CD3 reconstitution (P = .003) were observed after T-depleted graft HCT. These data indicate that mismatched donor transplant after TCRαß/CD19 depletion represents an excellent alternative for younger children with IEI in need of an allograft.

Outcome of Hematopoietic Stem Cell Transplantation in patients with Mendelian Susceptibility to Mycobacterial Diseases.

Predisposition to mycobacterial infection is a key presenting feature of several rare inborn errors of intrinsic and innate immunity. Hematopoietic stem cell transplantation (HSCT) can be curative for such conditions, but published reports are few. We present a retrospective survey of the outcome of 11 affected patients (7 males, 4 females) who underwent HSCT between 2007 and 2019. Eight patients had disseminated mycobacterial infection prior to transplant. Median age at first transplant was 48 months (9 -192); three patients were successfully re-transplanted due to secondary graft failure. Donors were matched family (1), matched unrelated (3), and mismatched unrelated and haploidentical family (5 each). Stem cell source was peripheral blood (9), bone marrow (4), and cord blood (1). TCRαß/CD19 + depletion was performed in 6. Conditioning regimens were treosulfan, fludarabine (4), with additional thiotepa (in 8), and fludarabine, melphalan (2); all had serotherapy with alemtuzumab (8) or anti T-lymphocyte globulin (6). Median hospital stay was 113 days (36-330). Three patients developed acute grade I-II skin and one grade IV skin graft versus host disease. Four patients had immune-reconstitution syndrome. Two reactivated cytomegalovirus (CMV), 1 Epstein-Barr virus, and 3 adenovirus post HSCT. Nine are alive, 1 died early post-transplant from CMV, and the other was a late death from pneumococcal sepsis. Patients with active mycobacterial infection at HSCT continued anti-mycobacterial therapy for almost 12 months. In conclusion, HSCT is a successful treatment for patients with mycobacterial susceptibility even with disseminated mycobacterial infection and in the absence of an HLA matched donor.

Outcome of Non-hematological Autoimmunity After Hematopoietic Cell Transplantation in Children with Primary Immunodeficiency.

PURPOSE: Knowledge of post-hematopoietic cell transplantation (HCT) non-hematological autoimmune disease (AD) is far from satisfactory. METHOD: This multicenter retrospective study focuses on incidence, risk factors, and outcomes of post-HCT AD in 596 children with primary immunodeficiency (PID) who were transplanted from 2009 to 2018. RESULTS: The indications of HCT were severe combined immunodeficiency (SCID, n = 158, 27%) and non-SCID PID (n = 438, 73%). The median age at HCT was 2.3 years (range, 0.04 to 18.3 years). The 5-year overall survival for the entire cohort was 79% (95% cumulative incidence (CIN), 74-83%). The median follow-up of surviving patients was 4.3 years (0.08 to 14.7 years). The CIN of post-HCT AD was 3% (2-5%) at 1 year post-HCT, 7% (5-11%) at 5 years post-HCT, and 11% (7-17%) at 8 years post-HCT. The median onset of post-HCT AD was 2.2 years (0.12 to 9.6 years). Autoimmune thyroid disorder (n = 19, 62%) was the most common post-HCT AD, followed by neuromuscular disorders (n = 7, 22%) and rheumatological manifestations (n = 5, 16%). All patients but one required treatment for post-HCT AD. After multivariate analysis, age at transplant (p = 0.01) and T cell-depleted graft (p < 0.001) were significant predictors of post-HCT AD. None of the T cell-depleted graft recipients developed post-HCT AD. Patients with a lower CD3+ count at 6 months post-HCT had a significant higher incidence of post-HCT AD compared to disease controls. Graft-versus-host disease, viral infection, and donor chimerism had no association with post-HCT AD. CONCLUSION: Post-HCT AD occurred in 11% at 8 years post-HCT and its occurrence was associated with older age at HCT and unmanipulated graft.

Outcome of autoimmune cytopenia after hematopoietic cell transplantation in primary immunodeficiency.

BACKGROUND: Post hematopoietic cell transplantation (HCT) autoimmune cytopenia (AIC) is a potentially life-threatening complication, but studies focusing on large cohorts of patients transplanted for primary immunodeficiency are lacking. OBJECTIVES: This study sought to determine the incidence, risk factors, and outcomes of post-HCT AIC and B-lymphocyte function following rituximab. METHODS: We retrospectively studied 502 children with primary immunodeficiency who were transplanted at our center between 1987 and 2018. RESULTS: Thirty-six patients (9%) developed post-HCT AIC, with a median onset of 6.5 months post-HCT. On univariate analysis, pre-HCT AIC, mismatched donor, alemtuzumab, anti-thymocyte antiglobulin, and acute and chronic graft versus host disease were significantly associated with post-HCT AIC. After multivariate analysis, alemtuzumab (subdistribution hazard ratio, 9.0; 95% CI, 1.50-54.0; P = .02) was independently associated with post-HCT AIC. Corticosteroid and high-dose intravenous immunoglobulin achieved remission in 50% (n = 18), additional rituximab led to remission in 25% (n = 9), and the remaining 25% were treated with a combination of various modalities including sirolimus (n = 5), bortezomib (n = 3), mycophenolate mofetil (n = 2), splenectomy (n = 2), and second HCT (n = 3). The mortality of post-HCT AIC reduced from 25% (4 of 16) prior to 2011 to 5% (1 of 20) after 2011. The median follow-up of 5.8 years (range, 0.4 to 29.1 years) showed that 26 of 30 survivors (87%) were in complete remission, and 4 were in remission with ongoing sirolimus and low-dose steroids. Of the 17 who received rituximab, 7 had B-lymphocyte recovery, 5 had persistent low B-lymphocyte count and remained on intravenous immunoglobulin replacement, 2 had second HCT, and 3 died. CONCLUSIONS: The frequency of post HCT AIC in our cohort was 9%, and the most significant risk factors for its occurrence were the presence of graft versus host disease and the use of alemtuzumab.

New graft manipulation strategies improve the outcome of mismatched stem cell transplantation in children with primary immunodeficiencies.

BACKGROUND: Mismatched stem cell transplantation is associated with a high risk of graft loss, graft-versus-host disease (GvHD), and transplant-related mortality. Alternative graft manipulation strategies have been used over the last 11 years to reduce these risks. OBJECTIVE: We investigated the outcome of using different graft manipulation strategies among children with primary immunodeficiencies. METHODS: Between 2006 and 2017, 147 patients with primary immunodeficiencies received 155 mismatched grafts: 30 T-cell receptor (TCR) αß/CD19-depleted grafts, 43 cord blood (CB) grafts (72% with no serotherapy), 17 CD34+ selection with T-cell add-back grafts, and 65 unmanipulated grafts. RESULTS: The estimated 8-year survival of the entire cohort was 79%, transplant-related mortality was 21.7%, and the graft failure rate was 6.7%. Posttransplantation viral reactivation, grade II to IV acute graft-versus-host disease (aGvHD), and chronic graft-versus-host disease (cGvHD) complicated 49.6%, 35%, and 15% of transplantations, respectively. Use of TCRαß/CD19 depletion was associated with a significantly lower incidence of grade II to IV aGvHD (11.5%) and cGvHD (0%), although with a greater incidence of viral reactivation (70%) in comparison with other grafts. T-cell immune reconstitution was robust among CB transplants, although with a high incidence (56.7%) of grade II to IV aGvHD. Stable full donor engraftment was significantly greater at 80% among TCRαß+/CD19+-depleted and CB transplants versus 40% to 60% among the other groups. CONCLUSIONS: Rapidly accessible CB and haploidentical grafts are suitable alternatives for patients with no HLA-matched donor. Cord transplantation without serotherapy and TCRαß+/CD19+-depleted grafts produced comparable survival rates of around 80%, although with a high rate of aGvHD with the former and a high risk of viral reactivation with the latter that need to be addressed.

Respiratory Health and Related Quality of Life in Patients with Congenital Agammaglobulinemia in the Northern Region of the UK.

INTRODUCTION: Patients with congenital agammaglobulinemia, characterized by a defect in B lymphocyte differentiation causing B alymphocytosis, require life-long IgG replacement. There is scant literature regarding the effectiveness of IgG treatment at preventing mucosal (particularly sinopulmonary tract) infection and whether current management adequately restores "normal" health and quality of life (QoL). We aimed to document infective episodes pre- and post-commencing IgG replacement, determine any change in lung function and structure and assess respiratory status and QoL in a cohort of patients treated in Newcastle. METHODS: Clinical data were extracted from medical records of 15 patients identified from the immunology database, focusing on infective episodes, serial chest CT and spirometry results. Thirteen patients completed a selection of standardized and validated questionnaires assessing physical health, respiratory health and QoL. RESULTS: Pediatric patients on IgG therapy suffered fewer infections per patient year (0.74) than adults (2.13). 6/14 patients showed deteriorating respiratory status despite adequate therapy. Health questionnaires revealed a significant burden of respiratory disease on a patient's life. CONCLUSION: Clinical data showed patients with congenital agammaglobulinemia receiving immunoglobulin therapy retained a higher than average infection rate, most of which affected mucosal barriers. Most patients self-reported worse respiratory symptoms, a lower respiratory-related QoL and a lower general health QoL relative to a healthy population. Most participants had progressive structural lung damage and decreased lung function. These results suggest that current management is not entirely effective at preventing deterioration of respiratory health or restoring QoL.

Neurological findings and genetic alterations in patients with Kostmann syndrome and HAX1 mutations.

OBJECTIVES: To describe the clinical profile and the prevalence of severe congenital neutropenia (SCN) and HAX1 mutations, so-called Kostmann syndrome, in France. STUDY DESIGN: Two pedigrees were identified from the French registry. RESULTS: The study included five subjects (three males), which represent 0.7% of the 759 SCN cases registered in France. The age at diagnosis was 0.3 years (range: 0.1-1.2 years) and the median age at the last follow-up was 7.3 years (range: 1.2-17.8 years). A novel large homozygous deletion of the HAX1 gene (exons 2-5) was found in one pedigree; while, a homozygous frameshift mutation was identified in exon 3 (c.430dupG, p.Val144fs) in the second pedigree. Severe bacterial infections were observed in four patients, including two cases of sepsis, one case of pancolitis, a lung abscess, and recurrent cellulitis and stomatitis. During routine follow-up, the median neutrophil value was 0.16 × 10(9)/L, associated with monocytosis (2 × 10(9)/L). Bone marrow (BM) smears revealed a decrease of the granulocytic lineage with no mature myeloid cells above the myelocytes. One patient died at age 2 from neurological complications, while two other patients, including one who underwent a hematopoietic stem cell transplantation (HSCT) at age 5, are living with very severe neurological retardation. CONCLUSIONS: SCN with HAX1 mutations, is a rare sub type of congenital neutropenia, mostly observed in population from Sweden and Asia minor, associating frequently neurological retardation, when the mutations involved the B isoform of the protein.

Low-dose serotherapy improves early immune reconstitution after cord blood transplantation for primary immunodeficiencies.

Cord blood transplantation (CBT) is curative for many primary immunodeficiencies (PIDs) but is associated with risks of viral infection and graft-versus-host disease (GvHD). Serotherapy reduces GvHD but potentially increases the risk of viral infection by delaying immune reconstitution. Because many PID patients have pre-existing viral infections, the optimal dose of serotherapy is unclear. We performed a retrospective analysis in 34 consecutive PID patients undergoing CBT and compared immune reconstitution, viral infection, GvHD, mortality, and long-term immune function between high-dose (n = 11) and low-dose (n = 9) serotherapy. Serotherapy dose had no effect on neutrophil engraftment. Median CD3(+) engraftment occurred at 92.5 and 97 days for high- and low-dose serotherapy, respectively. The low-dose serotherapy group had higher CD3(+), CD4(+), and early thymic emigrant counts at 4 months compared with the high-dose group. GvHD severity and number of viral infections did not differ between serotherapy doses. Survival from the transplantation process was 90.9% for high-dose and 100% for low-dose groups. In conclusion, low-dose serotherapy enhanced T cell reconstitution and thymopoiesis during the first year after CBT with no increase in GvHD.

Treosulfan-based conditioning regimens for hematopoietic stem cell transplantation in children with primary immunodeficiency: United Kingdom experience.

Children with primary immunodeficiency diseases, particularly those less than 1 year of age, experience significant toxicity after hematopoietic stem cell transplantation, with busulfan- or melphalan-based conditioning. Treosulfan causes less veno-occlusive disease than busulfan and does not require pharmacokinetic monitoring. We report its use in 70 children. Children received 42 g/m(2) or 36 g/m(2) with cyclophosphamide 200 mg/kg (n = 30) or fludarabine 150 mg/m(2) (n = 40), with alemtuzumab in most. Median age at transplantation was 8.5 months (range, 1.2-175 months); 46 (66%) patients were 12 months of age or younger. Donors were as follows: matched sibling donor, 8; matched family donor, 13; haploidentical, 4; and unrelated, 45. Median follow-up was 19 months (range, 1-47 months). Overall survival was 81%, equivalent in those age less or greater than 1 year. Skin toxicity was common. Veno-occlusive disease occurred twice with cyclophosphamide. Eighteen patients (26%) had graft-versus-host disease, and only 7 (10%) greater than grade 2. Two patients rejected; 24 of 42 more than 1 year after transplantation had 100% donor chimerism. The remainder had stable mixed chimerism. T-cell chimerism was significantly better with fludarabine. Long-term follow-up is required, but in combination with fludarabine, treosulfan is a good choice of conditioning for hematopoietic stem cell transplantation in primary immunodeficiency disease.

Lymphoid bronchiolitis presenting at birth in an immunocompetent child: Chronic interstitial lung disease of unknown aetiology.

A female infant presented at birth with respiratory distress, which was subsequently shown to be secondary to lymphoid bronchiolitis, an exceptionally rare condition in childhood. Over the following 13 years there has been a slow progressive deterioration in her respiratory status with forced expiratory volume in 1 sec currently 40% predicted. Tests for connective tissue disease, infection, or immunodeficiency have all been negative and in the absence of any other explanation we postulate that this severe problem may have occurred as a consequence of an unrecognized intrauterine infection.