Allogeneic hematopoietic cell transplantation for primary immune deficiency diseases: current status and critical needs

A rare disease: ZAP70 deficiency

Zeta associated protein (ZAP) 70 deficiency is a rare disease. ZAP70 deficiency results in an autosomal recessive form of severe combined immunodeficiency (SCID) that is characterized by a selective absence of CD8 T cells. The diagnosis should be suspected in patients presenting with a severe combined immunodeficiency phenotype and selective deficiency of CD8 T cells. Sequencing of the ZAP70 gene can confirm the diagnosis. We wanted to emphasize that immunodeficiencies should also be remembered in the differential diagnosis by presenting a 5-month-old patient who applied to our clinic with complaints of skin rash and cough, was given respiratory support with mechanical ventilation for a long time, and was diagnosed with ZAP70 deficiency.

Measuring the effect of newborn screening on survival after haematopoietic cell transplantation for severe combined immunodeficiency: a 36-year longitudinal study from the Primary Immune Deficiency Treatment Consortium

BACKGROUND

Severe combined immunodeficiency (SCID) is fatal unless durable adaptive immunity is established, most commonly through allogeneic haematopoietic cell transplantation (HCT). The Primary Immune Deficiency Treatment Consortium (PIDTC) explored factors affecting the survival of individuals with SCID over almost four decades, focusing on the effects of population-based newborn screening for SCID that was initiated in 2008 and expanded during 2010-18.

METHODS

We analysed transplantation-related data from children with SCID treated at 34 PIDTC sites in the USA and Canada, using the calendar time intervals 1982-89, 1990-99, 2000-09, and 2010-18. Categorical variables were compared by χ2 test and continuous outcomes by the Kruskal-Wallis test. Overall survival was estimated by the Kaplan-Meier method. A multivariable analysis using Cox proportional hazards regression models examined risk factors for HCT outcomes, including the variables of time interval of HCT, infection status and age at HCT, trigger for diagnosis, SCID type and genotype, race and ethnicity of the patient, non-HLA-matched sibling donor type, graft type, GVHD prophylaxis, and conditioning intensity.

FINDINGS

For 902 children with confirmed SCID, 5-year overall survival remained unchanged at 72%-73% for 28 years until 2010-18, when it increased to 87% (95% CI 82·1-90·6; n=268; p=0·0005). For children identified as having SCID by newborn screening since 2010, 5-year overall survival was 92·5% (95% CI 85·8-96·1), better than that of children identified by clinical illness or family history in the same interval (79·9% [69·5-87·0] and 85·4% [71·8-92·8], respectively [p=0·043]). Multivariable analysis demonstrated that the factors of active infection (hazard ratio [HR] 2·41, 95% CI 1·56-3·72; p<0·0001), age 3·5 months or older at HCT (2·12, 1·38-3·24; p=0·001), Black or African-American race (2·33, 1·56-3·46; p<0·0001), and certain SCID genotypes to be associated with lower overall survival during all time intervals. Moreover, after adjusting for several factors in this multivariable analysis, HCT after 2010 no longer conveyed a survival advantage over earlier time intervals studied (HR 0·73, 95% CI 0·43-1·26; p=0·097). This indicated that younger age and freedom from infections at HCT, both directly driven by newborn screening, were the main drivers for recent improvement in overall survival.

INTERPRETATION

Population-based newborn screening has facilitated the identification of infants with SCID early in life, in turn leading to prompt HCT while avoiding infections. Public health programmes worldwide can benefit from this definitive demonstration of the value of newborn screening for SCID.

FUNDING

National Institute of Allergy and Infectious Diseases, Office of Rare Diseases Research, and National Center for Advancing Translational Sciences.

The diagnosis of severe combined immunodeficiency: Implementation of the PIDTC 2022 Definitions

BACKGROUND

Shearer et al in 2014 articulated well-defined criteria for the diagnosis and classification of severe combined immunodeficiency (SCID) as part of the Primary Immune Deficiency Treatment Consortium's (PIDTC's) prospective and retrospective studies of SCID.

OBJECTIVE

Because of the advent of newborn screening for SCID and expanded availability of genetic sequencing, revision of the PIDTC 2014 Criteria was needed.

METHODS

We developed and tested updated PIDTC 2022 SCID Definitions by analyzing 379 patients proposed for prospective enrollment into Protocol 6901, focusing on the ability to distinguish patients with various SCID subtypes.

RESULTS

According to PIDTC 2022 Definitions, 18 of 353 patients eligible per 2014 Criteria were considered not to have SCID, whereas 11 of 26 patients ineligible per 2014 Criteria were determined to have SCID. Of note, very low numbers of autologous T cells (<0.05 × 109/L) characterized typical SCID under the 2022 Definitions. Pathogenic variant(s) in SCID-associated genes was identified in 93% of patients, with 7 genes (IL2RG, RAG1, ADA, IL7R, DCLRE1C, JAK3, and RAG2) accounting for 89% of typical SCID. Three genotypes (RAG1, ADA, and RMRP) accounted for 57% of cases of leaky/atypical SCID; there were 13 other rare genotypes. Patients with leaky/atypical SCID were more likely to be diagnosed at more than age 1 year than those with typical SCID lacking maternal T cells: 20% versus 1% (P < .001). Although repeat testing proved important, an initial CD3 T-cell count of less than 0.05 × 109/L differentiated cases of typical SCID lacking maternal cells from leaky/atypical SCID: 97% versus 7% (P < .001).

CONCLUSIONS

The PIDTC 2022 Definitions describe SCID and its subtypes more precisely than before, facilitating analyses of SCID characteristics and outcomes.

The diagnosis of severe combined immunodeficiency (SCID): The Primary Immune Deficiency Treatment Consortium (PIDTC) 2022 Definitions

Severe combined immunodeficiency (SCID) results from defects in the differentiation of hematopoietic stem cells into mature T lymphocytes, with additional lymphoid lineages affected in particular genotypes. In 2014, the Primary Immune Deficiency Treatment Consortium published criteria for diagnosing SCID, which are now revised to incorporate contemporary approaches. Patients with typical SCID must have less than 0.05 × 109 autologous T cells/L on repetitive testing, with either pathogenic variant(s) in a SCID-associated gene, very low/undetectable T-cell receptor excision circles or less than 20% of CD4 T cells expressing naive markers, and/or transplacental maternally engrafted T cells. Patients with less profoundly impaired autologous T-cell differentiation are designated as having leaky/atypical SCID, with 2 or more of these: low T-cell numbers, oligoclonal T cells, low T-cell receptor excision circles, and less than 20% of CD4 T cells expressing naive markers. These patients must also have either pathogenic variant(s) in a SCID-associated gene or reduced T-cell proliferation to certain mitogens. Omenn syndrome requires a generalized erythematous rash, absent transplacentally acquired maternal engraftment, and 2 or more of these: eosinophilia, elevated IgE, lymphadenopathy, hepatosplenomegaly. Thymic stromal defects and other causes of secondary T-cell deficiency are excluded from the definition of SCID. Application of these revised Primary Immune Deficiency Treatment Consortium 2022 Definitions permits precise categorization of patients with T-cell defects but does not imply a preferred treatment strategy.

Global and Local Manipulation of DNA Repair Mechanisms to Alter Site-Specific Gene Editing Outcomes in Hematopoietic Stem Cells

Monogenic disorders of the blood system have the potential to be treated by autologous stem cell transplantation of ex vivo genetically modified hematopoietic stem and progenitor cells (HSPCs). The sgRNA/Cas9 system allows for precise modification of the genome at single nucleotide resolution. However, the system is reliant on endogenous cellular DNA repair mechanisms to mend a Cas9-induced double stranded break (DSB), either by the non-homologous end joining (NHEJ) pathway or by the cell-cycle regulated homology-directed repair (HDR) pathway. Here, we describe a panel of ectopically expressed DNA repair factors and Cas9 variants assessed for their ability to promote gene correction by HDR or inhibit gene disruption by NHEJ at the HBB locus. Although transient global overexpression of DNA repair factors did not improve the frequency of gene correction in primary HSPCs, localization of factors to the DSB by fusion to the Cas9 protein did alter repair outcomes toward microhomology-mediated end joining (MMEJ) repair, an HDR event. This strategy may be useful when predictable gene editing outcomes are imperative for therapeutic success.

Multicenter Outcome of Hematopoietic Stem Cell Transplantation for Primary Immune Deficiency Disorders in India

Background

Hematopoietic stem cell transplantation (HSCT) is the curative option for many primary immune deficiency disorders (PID). In the last 5 years, increased awareness, availability of diagnostics based on flow cytometry, genetic testing, improved supportive care, use of reduced toxicity conditioning, and success of haploidentical donor HSCT have improved access to HSCT for children with PID in India. We present results on children with PID who underwent HSCT across India and the factors that influenced outcome.

Patients and Methods

We collected retrospective data on the outcome of HSCT for PID from seven centers. We analyzed the impact of the type of PID, conditioning regimen, time period of HSCT- before or after January 2016, graft versus host disease prophylaxis, cause of mortality and overall survival.

Results

A total of 228 children underwent HSCT for PID at a median age of 12 months (range, 1 to 220 months) with a median follow up of 14.4 months. Infants accounted for 51.3% of the cohort and the male female ratio was 3:1. SCID (25%) and HLH (25%) were the more frequent diagnoses. Matched family donor was available in 36.4% and 44.3% children had a haploidentical HSCT. Reduced and myeloablative conditioning regimens were used with 64% children receiving a treosulfan based conditioning regimen. Peripheral blood stem cells were the predominant graft source at 69.3%. The survival in infants (60.2%) was inferior to children aged over 1 year (75.7% p value = 0.01). Children with Wiskott Aldrich syndrome (74.3%) and chronic granulomatous disease (82.6%) had the best outcomes. The survival was superior in children receiving HSCT from a matched sibling (78%) versus an alternate donor HSCT (61% p value = 0.04). In the cohort transplanted after January 2016 survival improved from 26.8% to 77.5% (p value = 0.00). Infection remains the main cause of mortality at in over 50% children. The 5-year overall survival rate was 68%.

Conclusion

Survival of children with PID undergoing HSCT in India has improved dramatically in last 5 years. Alternate donor HSCT is now feasible and has made a therapeutic option accessible to all children with PID.

Infections in Infants with SCID: Isolation, Infection Screening, and Prophylaxis in PIDTC Centers

PURPOSE

The Primary Immune Deficiency Treatment Consortium (PIDTC) enrolled children with severe combined immunodeficiency (SCID) in a prospective natural history study of hematopoietic stem cell transplant (HSCT) outcomes over the last decade. Despite newborn screening (NBS) for SCID, infections occurred prior to HSCT. This study's objectives were to define the types and timing of infection prior to HSCT in patients diagnosed via NBS or by family history (FH) and to understand the breadth of strategies employed at PIDTC centers for infection prevention.

METHODS

We analyzed retrospective data on infections and pre-transplant management in patients with SCID diagnosed by NBS and/or FH and treated with HSCT between 2010 and 2014. PIDTC centers were surveyed in 2018 to understand their practices and protocols for pre-HSCT management.

RESULTS

Infections were more common in patients diagnosed via NBS (55%) versus those diagnosed via FH (19%) (p = 0.012). Outpatient versus inpatient management did not impact infections (47% vs 35%, respectively; p = 0.423). There was no consensus among PIDTC survey respondents as to the best setting (inpatient vs outpatient) for pre-HSCT management. While isolation practices varied, immunoglobulin replacement and antimicrobial prophylaxis were more uniformly implemented.

CONCLUSION

Infants with SCID diagnosed due to FH had lower rates of infection and proceeded to HSCT more quickly than did those diagnosed via NBS. Pre-HSCT management practices were highly variable between centers, although uses of prophylaxis and immunoglobulin support were more consistent. This study demonstrates a critical need for development of evidence-based guidelines for the pre-HSCT management of infants with SCID following an abnormal NBS.

TRIAL REGISTRATION

NCT01186913.

Malignancy post-hematopoietic stem cell transplant in patients with primary immunodeficiency

INTRODUCTION

Hematopoietic cell transplantation (HCT) is a curative treatment for an expanding number of primary immunodeficiencies (PIDs). Malignancies are more common in patients with PID than in the general population, and this review will discuss whether a successful HCT is expected to abolish or alter this risk. Second malignancy post HCT for a malignant disease is well known to occur, but generally less expected in patients transplanted for PID.

AREAS COVERED

This article reviews recently published literature focusing on the pattern of malignancy in children with PID, incidence, and risk factors for developing malignancy post-HCT for PID and possible strategies to reduce the risks.

EXPERT OPINION

Survival post HCT for PID has improved dramatically in the last 20 years and the genomic revolution has led to an expanding number of indications. To improve long-term quality of life attention needs to focus on late effects, including the possibility of malignancy occurring more frequently than expected in the general population, understand the risks and improve the process of transplantation in order to minimize them. Further studies are needed.

Immune reconstitution after HSCT in SCID-a cohort of conditioned and unconditioned patients

Allogeneic hematopoietic stem cell transplantation (HSCT) is the effective mean of immune restoration in severe combined immunodefiency (SCID). Usually, HSCT without cytoreductive conditioning is attempted. Nevertheless, conditioning procedures are still preferred in a subset of patients. Herein, we describe the immunological outcome in a cohort of conditioned and unconditioned patients, from diagnosis, through transplantation, to follow-up. This retrospective study was conducted on 17 patients with SCID (10 conditioned, 7 unconditioned) who later underwent HSCT. Immune reconstitution was assessed in the post-transplant year by quantification of T cell receptor excision circles (TRECs) and kappa-deleting recombination excision circles (KRECs), among additional laboratory and clinical evaluations. Unconditioned patients were diagnosed and transplanted earlier. TREC and KREC quantification showed a gradual increase in both groups, with higher levels in the conditioned group. Engraftment percentages differed drastically between groups, favoring the conditioned group. Unconditioned patients were significantly more dependent on intravenous immunoglobulins (IVIGs). One patient from each group succumbed to disease complications. Conditioning demonstrated superior laboratorial outcomes. Patients with unique characteristics (i.e., consanguinity, Bacillus Calmette-Guérin vaccination, impaired access to IVIG) may require personalized considerations. The effort to implement secondary prevention of SCID with newborn screening should continue.

Successful Salvage Haploidentical Alpha-Beta T Cell-Depleted Stem Cell Transplantation After Busulfan-Based Myeloablation in a Patient With IPEX Syndrome: A Case Report

BACKGROUND

X-linked immunodysregulation syndrome with polyendocrinopathy and enteropathy (IPEX) is caused by FOXP3 gene mutations that block the generation of regulatory T lymphocytes. We report an 18-month-old boy with classic IPEX who underwent 2 hematopoietic stem cell transplantations (HSCTs).

METHODS

The first HSCT from an unrelated 8/10 HLA-matched umbilical cord blood donor (UCB) was performed after a conditioning regimen consisting of treosulfan, fludarabine, thiotepa, and thymoglobulin. Due to complete rejection of the UCB transplant, a second transplantation from a 6/10 HLA-matched mother was performed after alpha-beta T-cell depletion. The second conditioning regimen consisted of busulfan, fludarabine, a single dose of cyclophosphamide 1 g/m², and Grafalon (Neovii Pharmaceuticals, Rapperswil, Switzerland). The T-cell depletion product contained 15.06 x 10⁶ CD34+ cells per kilogram body weight (BW) and 4.19 x 10⁵ alpha-beta T lymphocytes per kilogram BW. Due to acute graft rejection, the boy was treated with thymoglobulin, and full donor chimerism in both T lymphocytes and mononuclear cells was achieved. The immunosuppressive therapy was stopped 1 year after transplantation. To date, the patient remains free from graft-vs-host disease (GVHD) and immunosuppression.

CONCLUSIONS

HSCT after busulfan-based reduced-toxicity conditioning in patients with IPEX syndrome is feasible and well tolerated and can result in full donor engraftment. Monitoring of chimerism and aggressive therapy in cases of graft rejection are warranted due to the high reactivity of residual autologous T lymphocytes. T-cell depletion reduces the risk of GVHD and the need for steroid therapy, which is especially challenging in patients with diabetes.

Tandem Orthotopic Living Donor Liver Transplantation Followed by Same Donor Haploidentical Hematopoietic Stem Cell Transplantation for DOCK8 Deficiency

BACKGROUND

An 11-year-old girl with dedicator of cytokinesis 8 (DOCK8) deficiency was proposed for potentially curative hematopoietic stem cell transplantation (HSCT), the donor being her haploidentical mother. However, end-stage liver disease caused by chronic Cryptosporidium infection required liver transplantation before HSCT.

METHODS

Consequently, a staged approach of a sequential liver transplant followed by a HSCT was planned with her mother as the donor for both liver and HSCT.

RESULTS

The patient successfully underwent a left-lobe orthotopic liver transplant; however, she developed a biliary leak delaying the HSCT. Notably, the recipient demonstrated 3% donor lymphocyte chimerism in her peripheral blood immediately before HSCT. Haploidentical-related donor HSCT performed 2 months after liver transplantation was complicated by the development of acyclovir-resistant herpes simplex virus viremia, primary graft failure, and sinusoidal obstruction syndrome. The patient died from sinusoidal obstruction syndrome-associated multiorgan failure with Candida sepsis on day +40 following HSCT.

CONCLUSIONS

We discuss the many considerations inherent to planning for HSCT preceded by liver transplant in patients with primary immunodeficiencies, including the role of prolonged immunosuppression and the risk of infection before immune reconstitution. We also discuss the implications of potential recipient sensitization against donor stem cells precipitated by exposure of the recipient to the donor lymphocytes from the transplanted organ.

Recommendations for Screening and Management of Late Effects in Patients with Severe Combined Immunodeficiency after Allogenic Hematopoietic Cell Transplantation: A Consensus Statement from the Second Pediatric Blood and Marrow Transplant Consortium International Conference on Late Effects after Pediatric HCT

Severe combined immunodeficiency (SCID) is effectively treated with hematopoietic cell transplantation (HCT), with overall survival approaching 90% in contemporary reports. However, survivors are at risk for developing late complications because of the variable durability of high-quality immune function, underlying genotype of SCID, comorbidities due to infections in the pretransplantation and post-transplantation periods, and use of conditioning before transplantation. An international group of transplantation experts was convened in 2016 to review the current knowledge of late effects seen in SCID patients after HCT and to develop recommendations for screening and monitoring for late effects. This report provides recommendations for screening and management of pediatric and adult SCID patients treated with HCT.

Primary Immune Deficiency Treatment Consortium (PIDTC) update

The Primary Immune Deficiency Treatment Consortium (PIDTC) is a collaboration of 41 North American centers studying therapy for rare primary immune deficiency diseases (PIDs), including severe combined immune deficiency (SCID), Wiskott-Aldrich syndrome (WAS), and chronic granulomatous disease (CGD). An additional 3 European centers have partnered with the PIDTC to study CGD. Natural history protocols of the PIDTC analyze outcomes of treatment for rare PIDs in multicenter longitudinal retrospective, prospective, and cross-sectional studies. Since 2009, participating centers have enrolled more than 800 subjects on PIDTC protocols for SCID, and enrollment in the studies on WAS and CGD is underway. Four pilot projects have been funded, and 12 junior investigators have received fellowship awards. Important publications of the consortium describe the outcomes of hematopoietic cell transplantation for SCID during 2000-2009, diagnostic criteria for SCID, and the pilot project of newborn screening for SCID in the Navajo Nation. The PIDTC Annual Scientific Workshops provide an opportunity to strengthen collaborations with junior investigators, patient advocacy groups, and international colleagues. Funded by the National Institute of Allergy and Infectious Diseases and the Office of Rare Diseases Research, National Center for Advancing Translational Sciences, the PIDTC has recently received renewal for another 5 years. Here we review accomplishments of the group, projects underway, highlights of recent workshops, and challenges for the future.

Successful Unrelated Cord Blood Stem Cell Transplantation in an X-linked Chronic Granulomatous Disease Patient with Disseminated BCG-induced Infection

A 19-month-old boy with chronic granulomatous disease (CGD) received umbilical cord blood transplantation (UCBT) from an unrelated donor after experiencing a life-threatening disseminated Bacillus Calmette-Guérin infection. After busulfan and cyclophosphamide conditioning, we performed a 5/6-matched UCBT. Engraftment and mixed chimerism was 100% in peripheral blood, and 100% of his neutrophils had normal oxidative burst activity on day 17. The patient is now 3 years old, free from infection, and growing well. To our knowledge, this is the second case of CGD treated with UCBT in Taiwan. His successful outcome illustrates that UCBT in a patient with CGD should be considered early if a human leukocyte antigen-matched donor is not available or the patient has just recovered from a severe infection.

Practice parameter for the diagnosis and management of primary immunodeficiency

The American Academy of Allergy, Asthma & Immunology (AAAAI) and the American College of Allergy, Asthma & Immunology (ACAAI) have jointly accepted responsibility for establishing the "Practice parameter for the diagnosis and management of primary immunodeficiency." This is a complete and comprehensive document at the current time. The medical environment is a changing environment, and not all recommendations will be appropriate for all patients. Because this document incorporated the efforts of many participants, no single individual, including those who served on the Joint Task Force, is authorized to provide an official AAAAI or ACAAI interpretation of these practice parameters. Any request for information about or an interpretation of these practice parameters by the AAAAI or ACAAI should be directed to the Executive Offices of the AAAAI, the ACAAI, and the Joint Council of Allergy, Asthma & Immunology. These parameters are not designed for use by pharmaceutical companies in drug promotion.

Stem cell transplantation for primary immunodeficiency diseases: the North American experience

PURPOSE OF REVIEW

This review describes recent studies on outcomes after allogeneic hematopoietic cell transplantation for primary immunodeficiency in North America, including severe combined immunodeficiency (SCID), Wiskott-Aldrich syndrome and chronic granulomatous disease.

RECENT FINDINGS

Using uniform diagnostic criteria, the Primary Immune Deficiency Treatment Consortium described the baseline characteristics of newly diagnosed infants with SCID in North America. Analysis of outcomes of hematopoietic cell transplantation for SCID in North America from 2000 to 2009 showed that young infants, and older infants without active infection, had excellent survival irrespective of type of donor or transplant approach with regard to conditioning. Although pretransplant conditioning with chemotherapy had a clear and strong negative impact on survival in infants with active infection at the time of transplant, among survivors, conditioning was associated with improved immune reconstitution. However, the potential late effects of conditioning in these infants remain to be characterized. Advances in transplant outcomes for Wiskott-Aldrich syndrome and chronic granulomatous disease support the strategy of early transplantation before the onset of severe complications; additional multicenter studies are needed to fully define optimal approaches.

SUMMARY

The formation of the Primary Immune Deficiency Treatment Consortium, a multiinstitutional North American consortium, has contributed to our understanding of outcomes after transplant for primary immunodeficiency.

A prospective outcome study of patients with profound combined immunodeficiency (P-CID)

This is a prospective outcome study of patients with profound combined immunodeficiency (P-CID) (study number DRKS00000497).

Combined immunodeficiencies (CID) are a heterogeneous group of inherited immune disorders with impaired T-cell development and (or) function manifesting through increased susceptibility to infections and (or) immune dysregulation. They can be delineated from severe CID (SCID) by their manifestation beyond the first year of life. Profound CID (P-CID) is a potentially life-threatening form of CID, in which stem cell transplant (SCT) is a relevant consideration at diagnosis.

The primary objective of the study is to provide natural history data on patients with P-CID, irrespective of whether they undergo hematopoietic stem cell transplant (HSCT) or not. The goals are to determine survival, the frequency of severe events, and quality of life (QOL) 5 years after study inclusion.

The secondary objective is to develop a risk model for P-CID patients. The model is developed from a set of clinical and laboratory parameters obtained at diagnosis, at study inclusion, and yearly thereafter.

The tertiary objectives of this study are to determine the effects of donor, recipient, and treatment factors on the outcome of HSCT. The goal is to determine the quality of engraftment and immunological reconstitution and to determine the effects of these parameters on clinical outcome.

The main hypothesis is that P-CID patients undergoing early HSCT have a better 5-year survival rate than patients who undergo late HSCT or are not transplanted.

This is a prospective multi-centre international cohort study (observational study).

Enrolled patients will be evaluated and treated according to local institutional protocols. They will receive comparable baseline and follow-up evaluations across all participating centres, irrespective of the therapeutic strategy at the individual site.

There will be at least 6 study visits (scheduled yearly) for all patients. Because of the variable history prior to study inclusion, a morbidity score is determined for each patient at study visit 1. For those patients undergoing HSCT, an additional 6 month post-HSCT visit will be scheduled. The study visits will document immunological parameters, severe events including major infections, and major manifestations of immune dysregulation, severe transplant-related events, and QOL.

Longitudinal Evaluation of Immune Reconstitution and B-cell Function After Hematopoietic Cell Transplantation for Primary Immunodeficiency

PURPOSE

Hematopoietic cell transplantation (HCT) provides a curative therapy for severe forms of primary immunodeficiencies (PID). While the timing and extent of T-cell reconstitution following transplant for PID has been studied in depth, less is known about the kinetics of B-cell development and long-term restoration of humoral functions, which been often reported to be suboptimal after HCT.

METHODS

We studied longitudinally B-cell development and function in a cohort of 13 PID patients transplanted between 1997 and 2010, with a follow-up ranging from 0.7 to 15 years. Flow cytometric analysis of naïve and antigen-experienced B-cell subsets and in vitro functional responses to CpG were compared with data from healthy children and correlated with the degree of B-cell chimerism and in vivo antibody production.

RESULTS

We found that total memory B-cells count remained below normal levels for the first 2 years of follow up and progressively normalized. Switched memory B-cells (CD19+CD27+IgD-IgM-) were restored early and better than IgM memory B-cells (CD19+CD27+IgD+IgM+), which remained significantly reduced long-term. The recovery of memory B-cells correlated with good in vivo humoral function and normalization of CpG-response. A complete B-cell reconstitution was usually associated with donor B-cells chimerism and pre-transplant conditioning. Donor source and the underlying genetic defect represented also important variables.

CONCLUSION

Monitoring of phenotypic and functional changes on B-cells following HCT may prove clinically relevant to tailor patients' care. In particular the analysis of IgM memory and switched memory B-cells in addition to in vitro B-cells stimulation are recommended before Ig replacement therapy (IgRT) discontinuation.

History and current status of newborn screening for severe combined immunodeficiency

The development of a T-cell receptor excision circle (TREC) assay utilizing dried blood spots in universal newborn screening has allowed the early detection of T-cell lymphopenia in newborns. Diagnosis of severe combined immunodeficiency (SCID) in affected infants in the neonatal period, while asymptomatic, permits early treatment and restoration of a functional immune system. SCID was the first immunodeficiency disease to be added to the Recommended Uniform Screening Panel of Core Conditions in the United States in 2010, and it is now implemented in 26 states in the U.S. This review covers the development of newborn screening for SCID, the biology of the TREC test, its current implementation in the U.S., new findings for SCID in the newborn screening era, and future directions.

Primary immunodeficiencies in the Netherlands: national patient data demonstrate the increased risk of malignancy

PURPOSE

To analyze the data of the national registry of all Dutch primary immune deficiency (PID) patients, according to the European Society for Immunodeficiencies (ESID) definitions.

RESULTS

In the Netherlands, 745 patients had been registered between 2009 and 2012. An overall prevalence of 4.0 per 100,000 inhabitants was calculated. The most prevalent PID was 'predominantly antibody disorder (PAD)' (60.4%). In total, 118 transplantations were reported, mostly hematopoietic stem cell transplantations (HSCT). Almost 10% of the PID patients suffered from a malignancy, in particular 'lymphoma' and 'skin cancer'. Compared to the general Dutch population, the relative risk of developing any malignancy was 2.3-fold increased, with a >10-fold increase for some solid tumors (thymus, endocrine organs) and hematological disease (lymphoma, leukemia), varying per disease category.

CONCLUSIONS

The incidence rate and characteristics of PID in the Netherlands are similar to those in other European countries. Compared to the general population, PID patients carry an increased risk to develop a malignancy.

Hematopoietic stem cell transplantation for primary immunodeficiencies

Allogeneic hematopoietic stem cell transplantation has been shown to be curative for well-described as well as newly discovered immunodeficiencies. However, it is difficulty to define a universal transplant regimen given the rarity of these disorders and the varied pathophysiology these disorders encompass. This article discusses those primary immunodeficiencies most commonly treated by hematopoietic stem cell transplant and describes the transplant issues specific to these disorders.

Transplantation outcomes for severe combined immunodeficiency, 2000-2009

BACKGROUND

The Primary Immune Deficiency Treatment Consortium was formed to analyze the results of hematopoietic-cell transplantation in children with severe combined immunodeficiency (SCID) and other primary immunodeficiencies. Factors associated with a good transplantation outcome need to be identified in order to design safer and more effective curative therapy, particularly for children with SCID diagnosed at birth.

METHODS

We collected data retrospectively from 240 infants with SCID who had received transplants at 25 centers during a 10-year period (2000 through 2009).

RESULTS

Survival at 5 years, freedom from immunoglobulin substitution, and CD3+ T-cell and IgA recovery were more likely among recipients of grafts from matched sibling donors than among recipients of grafts from alternative donors. However, the survival rate was high regardless of donor type among infants who received transplants at 3.5 months of age or younger (94%) and among older infants without prior infection (90%) or with infection that had resolved (82%). Among actively infected infants without a matched sibling donor, survival was best among recipients of haploidentical T-cell-depleted transplants in the absence of any pretransplantation conditioning. Among survivors, reduced-intensity or myeloablative pretransplantation conditioning was associated with an increased likelihood of a CD3+ T-cell count of more than 1000 per cubic millimeter, freedom from immunoglobulin substitution, and IgA recovery but did not significantly affect CD4+ T-cell recovery or recovery of phytohemagglutinin-induced T-cell proliferation. The genetic subtype of SCID affected the quality of CD3+ T-cell recovery but not survival.

CONCLUSIONS

Transplants from donors other than matched siblings were associated with excellent survival among infants with SCID identified before the onset of infection. All available graft sources are expected to lead to excellent survival among asymptomatic infants. (Funded by the National Institute of Allergy and Infectious Diseases and others.).

Transplantation tolerance: from theory to clinic

Tolerance induction and alloreactivity can be applied to the clinic for the transplantation of solid organs and in the treatment of human cancers respectively. Hematopoietic chimerism, the stable coexistence of host and donor blood cells, guarantees that a solid organ from the same donor will be tolerated without a requirement for maintenance immunosuppression, and it also serves as a platform for the adoptive immunotherapy of hematologic malignancies using donor lymphocyte infusions. This review focuses on clinically relevant methods for inducing hematopoietic chimerism and transplantation tolerance, with a special emphasis on reduced intensity transplantation conditioning and high dose, post-transplantation cyclophosphamide to prevent graft rejection and graft-versus-host disease (GVHD). Reduced intensity transplantation regimens permit a transient cooperation between donor and host immune systems to eradicate malignancy without producing GVHD. Their favorable toxicity profile also enables the application of allogeneic stem cell transplantation to treat non-malignant disorders of hematopoiesis and to induce tolerance for solid organ transplantation.

Gene correction of induced pluripotent stem cells derived from a murine model of X-linked chronic granulomatous disorder

Gene therapy presents an attractive alternative to allogeneic haematopoietic stem cell transplantation (HSCT) for treating patients suffering from primary immunodeficiency disorder (PID). The conceptual advantage of gene correcting a patient's autologous HSCs lies in minimizing or completely avoiding immunological complications arising from allogeneic transplantation while conferring the same benefits of immune reconstitution upon long-term engraftment. Clinical trials targeting X-linked chronic granulomatous disorder (X-CGD) have shown promising results in this context. However, long-term clinical benefits in these patients have been limited by issues of poor engraftment of gene-transduced cells coupled with transgene silencing and vector induced clonal proliferation. Novel vectors incorporating safety features such as self-inactivating (SIN) mutations in the long terminal repeats (LTRs) along with synthetic promoters driving lineage-restricted sustainable expression of the gp91phox transgene are expected to resolve the current pitfalls and require rigorous preclinical testing. In this chapter, we have outlined a protocol in which X-CGD mouse model derived induced pluripotent stem cells (iPSCs) have been utilized to develop a platform for investigating the efficacy and safety profiles of novel vectors prior to clinical evaluation.

Establishing diagnostic criteria for severe combined immunodeficiency disease (SCID), leaky SCID, and Omenn syndrome: the Primary Immune Deficiency Treatment Consortium experience

BACKGROUND

The approach to the diagnosis of severe combined immunodeficiency disease (SCID) and related disorders varies among institutions and countries.

OBJECTIVES

The Primary Immune Deficiency Treatment Consortium attempted to develop a uniform set of criteria for diagnosing SCID and related disorders and has evaluated the results as part of a retrospective study of SCID in North America.

METHODS

Clinical records from 2000 through 2009 at 27 centers in North America were collected on 332 children treated with hematopoietic stem cell transplantation (HCT), enzyme replacement therapy, or gene therapy for SCID and related disorders. Eligibility for inclusion in the study and classification into disease groups were established by using set criteria and applied by an expert review group.

RESULTS

Two hundred eighty-five (86%) of the patients were determined to be eligible, and 47 (14%) were not eligible. Of the 285 eligible patients, 84% were classified as having typical SCID; 13% were classified as having leaky SCID, Omenn syndrome, or reticular dysgenesis; and 3% had a history of enzyme replacement or gene therapy. Detection of a genotype predicting an SCID phenotype was accepted for eligibility. Reasons for noneligibility were failure to demonstrate either impaired lymphocyte proliferation or maternal T-cell engraftment. Overall (n = 332) rates of testing were as follows: proliferation to PHA, 77%; maternal engraftment, 35%; and genotype, 79% (mutation identified in 62%).

CONCLUSION

Lack of complete laboratory evaluation of patients before HCT presents a significant barrier to definitive diagnosis of SCID and related disorders and prevented inclusion of subjects in our observational HCT study. This lesson is critical for patient care, as well as the design of future prospective treatment studies for such children because a well-defined and consistent study population is important for precision in outcomes analysis.

Primary Immune Deficiency Treatment Consortium (PIDTC) report

The Primary Immune Deficiency Treatment Consortium (PIDTC) is a network of 33 centers in North America that study the treatment of rare and severe primary immunodeficiency diseases. Current protocols address the natural history of patients treated for severe combined immunodeficiency (SCID), Wiskott-Aldrich syndrome, and chronic granulomatous disease through retrospective, prospective, and cross-sectional studies. The PIDTC additionally seeks to encourage training of junior investigators, establish partnerships with European and other International colleagues, work with patient advocacy groups to promote community awareness, and conduct pilot demonstration projects. Future goals include the conduct of prospective treatment studies to determine optimal therapies for primary immunodeficiency diseases. To date, the PIDTC has funded 2 pilot projects: newborn screening for SCID in Navajo Native Americans and B-cell reconstitution in patients with SCID after hematopoietic stem cell transplantation. Ten junior investigators have received grant awards. The PIDTC Annual Scientific Workshop has brought together consortium members, outside speakers, patient advocacy groups, and young investigators and trainees to report progress of the protocols and discuss common interests and goals, including new scientific developments and future directions of clinical research. Here we report the progress of the PIDTC to date, highlights of the first 2 PIDTC workshops, and consideration of future consortium objectives.

Bone marrow transplantation in Schimke immuno-osseous dysplasia

Schimke immuno-osseous dysplasia (SIOD, OMIM 242900) is a rare autosomal recessive multisystem childhood disorder characterized by short stature, renal failure, T-cell immunodeficiency, and hypersensitivity to genotoxic agents. SIOD is associated with biallelic mutations in SMARCAL1 (SWI/SNF-related matrix-associated actin-dependent regulator of chromatin, subfamily a-like 1), which encodes a DNA stress response enzyme with annealing helicase activity. Two features of SIOD causing much morbidity and mortality are bone marrow failure and T-cell deficiency with the consequent opportunistic infections. To address the safety and efficacy of bone marrow transplantation (BMT) in SIOD, we reviewed the outcomes of the only five SIOD patients known to us in whom bone marrow or hematopoietic stem cell transplantation has been attempted. We find that only one patient survived the transplantation procedure and that the existing indicators of a good prognosis for bone marrow transplantation were not predictive in this small cohort. Given these observations, we also discuss some considerations for the poor outcomes.

Challenges and opportunities for international cooperative studies in pediatric hematopoeitic cell transplantation: priorities of the Westhafen Intercontinental Group

More than 20% of allogeneic hematopoietic cell transplantations (HCTs) are performed in children and adolescents at a large number of relatively small centers. Unlike adults, at least one-third of HCTs in children are performed for rare, nonmalignant indications. Clinical trials to improve HCT outcomes in children have been limited by small numbers and these pediatric-specific features. The need for a larger number of pediatric HCT centers to participate in trials has led to the involvement of international collaborative groups. Representatives of the Pediatric Blood and Marrow Transplant Consortium, European Group for Blood and Marrow Transplantation's Pediatric Working Group, International Berlin-Frankfurt-Munster (iBFm) Stem Cell Transplantation Committee, and Children's Oncology Group's Hematopoietic Stem Cell Transplantation Discipline Committee met on October 3, 2012, in Frankfurt, Germany to develop a consensus on the highest priorities in pediatric HCT. In addition, it explored the creation of an international consortium to develop studies focused on HCT in children and adolescents. This meeting led to the creation of an international HCT network, dubbed the Westhafen Intercontinental Group, to develop worldwide priorities and strategies to address pediatric HCT issues. This review outlines the priorities of need as identified by this consensus group.

HCT survival in ADA-SCID: what's the buzz?

In this issue of Blood, Hassan et al have turned the spotlight on hematopoietic stem cell transplantation (HCT) of adenosine deaminase (ADA)-deficient severe combined immunodeficiency (SCID). They opened up the curtain of beliefs on this therapy that enables facts to be separated from fiction.

Examining the use of ICD-9 diagnosis codes for primary immune deficiency diseases in New York State

PURPOSE

To use International Classification of Disease Codes (ICD-9) codes to investigate primary immune deficiency (PID) in New York State.

METHODS

We investigated the diagnosis of Primary Immune Deficiency (PID) in New York State (NYS) using the Statewide Planning and Research Cooperative System (SPARCS) database, a comprehensive data reporting system that collects ICD-9 codes for each patient hospitalized in NYS.

RESULTS

From 2000-2004 there were 13,539,358 hospitalizations for 4,777,295 patients; of these, 2,361 patients (0.05 %) were diagnosed with one or more of the ICD-9 codes for PID. Antibody defects were the most common diagnoses made. The PID population had significantly more Caucasians, and fewer African American or Hispanic subjects compared to the general population. Subjects with PID codes were younger, had longer hospitalizations, were less likely to have Medicare and more likely to have Medicaid or Blue Cross insurance. Most hospitalizations were due to respiratory and infectious diseases. Most patients resided in the most populous counties, Kings, New York and Queens, but the distribution of home zip codes was not proportional to county populations.

CONCLUSIONS

These data provide useful information on incidence and complications of selected PID diagnoses in one large state.

Effects of conditioning regimens and T cell depletion in hematopoietic cell transplantation for primary immune deficiency

This study analyzes the hematopoietic cell transplantation experience in patients with immune deficiency at a single institution. The objective is to comprehensively evaluate the short-term and long-term outcomes with various preparative regimens, donor grafts, and ex vivo manipulations to identify transplantation approaches that most likely favor early donor immune competency without generating excessive toxicity. Clinical outcomes were evaluated in 52 consecutive patients with immune deficiencies. Thirty-seven of the 52 patients (71%) survived with attenuation of their underlying disease. The use of a melphalan-based reduced-intensity conditioning preparative regimen and immunomagnetic CD3(+) T cell depletion techniques (when T cell depletion was indicated) were associated with improved event-free survival. Survivors who received a preparative regimen other than a melphalan-based reduced-intensity regimen suffered from therapy-related morbidities or chronic/recurrent infections. Our findings indicate that melphalan-based reduced-intensity conditioning regimens and immunomagnetic CD3(+) T cell depletion limit therapy-related toxicity, and demonstrate promising results for the early establishment of donor immune competency.

The case for newborn screening for severe combined immunodeficiency and related disorders

Early detection of primary immunodeficiency is recognized as important for avoiding infectious complications that compromise outcomes. In particular, severe combined immunodeficiency (SCID) is fatal in infancy unless affected infants can be diagnosed before the onset of devastating infections and provided with an immune system through allogenic hematopoietic cell transplantation, enzyme replacement, or gene therapy. A biomarker of normal T cell development, T cell receptor excision circles (TRECs), can be measured in DNA isolated from the dried blood spots routinely obtained for newborn screening; infants identified as lacking TRECs can thus receive confirmatory testing and prompt intervention. Early results of TREC testing of newborns in five states indicate that this addition to the newborn screening panel can be successfully integrated into state public health programs. A variety of cases with typical SCID genotypes and other T lymphocytopenic conditions have been detected in a timely manner and referred for appropriate early treatment.

Laboratory technology for population-based screening for severe combined immunodeficiency in neonates: the winner is T-cell receptor excision circles

The most profound primary immunodeficiency disease, severe combined immunodeficiency (SCID), is fatal in infancy unless affected infants are provided with an adaptive immune system through allogeneic hematopoietic cell transplantation, enzyme replacement, or gene therapy. However, most infants with SCID lack a family history or any clinical clues before the onset of infections, making this serious but treatable disease a candidate for population-based newborn screening. Of several approaches considered for SCID screening, testing for T-cell receptor excision circles (TRECs), a DNA biomarker of normal T-cell development, has proved successful. TREC numbers can be measured in DNA isolated from the dried bloodspots already routinely collected for newborn screening. Infants with low or absent TRECs can thus be identified and referred for confirmatory testing and prompt intervention. TREC testing of newborns is now being performed in several states, indicating that this addition to the newborn screening panel can be successfully integrated into state public health programs.

Hematopoietic stem cell transplantation for primary immunodeficiency diseases

Hematopoietic stem cell transplantation (HSCT) is now highly successfully curing a widening range of primary immunodeficiencies (PIDs). Better tissue typing, matching of donors, less toxic chemotherapy, better virus detection and treatment, improved supportive care, and graft-versus-host disease prophylaxis mean up to a 90% cure for severe combined immunodeficiency patients and a 70-80% cure for other PIDs given a matched unrelated donor, and rising to 95% for young patients with specific PIDs, such as Wiskott-Aldrich syndrome. Precise molecular diagnosis, detailed data on prognosis, and careful pre-HSCT assessment of infective lung and liver damage will ensure an informed benefit analysis of HSCT and the best outcome. It is now recognized that the best treatment option for chronic granulomatous disease is HSCT, which can also be curative for CD40 ligand deficiency and complex immune dysregulation disorders.

Neonatal screening for severe combined immunodeficiency

PURPOSE OF REVIEW

Population-based newborn screening for severe combined immunodeficiency (SCID) and related disorders has been instituted in five states, with several more planning to add this testing to their newborn screening panels. This review summarizes the rationale, development and implementation of SCID screening programs to date and highlights current and future challenges.

RECENT FINDINGS

Early results of T-cell receptor excision circle (TREC) testing newborns in pilot states indicate that this addition to the newborn screening panel can be successfully integrated into state public health programs. The TREC test has clinical validity and TRECs, as predicted, are an excellent biomarker of poor T lymphocyte production in the thymus or increased lymphocyte loss resulting in T-cell lymphopenia. A variety of cases with typical SCID genotypes and other conditions have been detected in a timely manner and referred for appropriate early treatment.

SUMMARY

Early detection of primary immunodeficiency is recognized as important for avoiding infectious complications that compromise outcomes. Routine screening of all newborns with the TREC test, implemented as part of an integrated public health program, can achieve presymptomatic diagnosis of SCID and other disorders with T-cell lymphopenia, allowing prompt and effective treatment and leading to a better understanding of the spectrum of these disorders and how to manage them.

A Markov model to analyze cost-effectiveness of screening for severe combined immunodeficiency (SCID)

OBJECTIVE

To evaluate the cost-effectiveness of universal neonatal screening for T cell lymphocytopenia in enhancing quality of life and life expectancy for children with severe combined immunodeficiency (SCID).

METHODS

Decision trees were created and analyzed to estimate the cost, life years, and quality adjusted life years (QALYs) across a population when universal screening for lack of T cells is used to detect SCID, as implemented in five states, compared to detection based on recognizing symptoms and signs of disease. Terminal values of each tree limb were derived through Markov models simulating the natural history of three cohorts: unaffected subjects; those diagnosed with SCID as neonates (early diagnosis); and those diagnosed after becoming symptomatic and arousing clinical suspicion (late diagnosis). Models considered the costs of screening and of care including hematopoietic cell transplantation for affected individuals. Key decision variables were derived from the literature and from a survey of families with children affected by SCID, which was used to describe the clinical history and healthcare utilization for affected subjects. Sensitivity analyses were conducted to explore the influence of these decision variables.

RESULTS

Over a 70-year time horizon, the average cost per infant was $8.89 without screening and $14.33 with universal screening. The model predicted that universal screening in the U.S. would cost approximately $22.4 million/year with a gain of 880 life years and 802 QALYs. Sensitivity analyses showed that screening test specificity and disease incidence were critical driving forces affecting the incremental cost-effectiveness ratio (ICER). Assuming a SCID incidence of 1/75,000 births and test specificity and sensitivity each at 0.99, screening remained cost-effective up to a maximum cost of $15 per infant screened.

CONCLUSION

At our current estimated screening cost of $4.22/infant, universal screening for SCID would be a cost effective means to improve quality and duration of life for children with SCID.

T cell and B Cell immunity can be reconstituted with mismatched hematopoietic stem cell transplantation without alkylator therapy in artemis-deficient mice using anti-natural killer cell antibody and photochemically treated sensitized donor T cells

Children with Artemis-deficient T(-)B(-)NK(+) severe combined immunodeficiency are at high risk for graft rejection from natural killer (NK) cells and toxicity from increased sensitivity to the alkylating agents used in mismatched hematopoietic stem cell transplantation (HSCT). We evaluated the use of a nonalkylating agent regimen before HSCT in Artemis-deficient (mArt(-/-)) C57Bl/6 (B6) mice to open marrow niches and achieve long-term multilineage engraftment with full T cell and B cell immune reconstitution. We found that partial depletion of both recipient NK cells using anti-NK1.1 monoclonal antibody and donor T cells sensitized to recipient splenocytes was necessary. BALB/c-sensitized T cells (STCs) were photochemically treated (PCT) with psoralen and UVA light to inhibit proliferation, reduce the risk of graft-versus-host disease (GVHD), and target host hematopoietic stem cells (HSCs). A dose of 4 × 10(5) PCT STCs coinjected with 1 × 10(5) lineage-depleted c-kit(+) BALB/c HSCs resulted in 43.9% ± 3.3% CD4(+) and 10.9% ± 1.2% CD8(+) donor T cells in blood, 29% ± 7.8% and 21.7% ± 4.0 donor B220(+) IgM(+) in spleen and bone marrow, and 15.0% ± 3.6% donor Gran-1(+) cells in bone marrow at 6 months post-HSCT versus 0.02% ± 0.01%, 0.13% ± 0.10%, 0.53% ± 0.16%, 0.49% ± 0.09%, and 0.20% ± 0.06%, respectively, in controls who did not receive PCT STCs. We found that STCs target host HSCs and that PCT STCs are detectable only up to 24 hours after infusion, in contrast to non-photochemically treated STCs, which proliferate resulting in fatal GVHD. Increased mortality in the groups receiving 4-6 × 10(5) PCT STCs was associated with evidence of GVHD, particularly in the recipients of 6 × 10(5) cells. These results demonstrate that blocking NK cell-mediated resistance and making niches in bone marrow are both essential to achieving multilineage engraftment of mismatched donor cells and T cell and B cell reconstitution, even though GVHD is not completely eliminated.

Hematopoietic stem cell transplantation for chronic granulomatous disease

Chronic granulomatous disease (CGD) is a primary immunodeficiency disease that is caused by the lack of 1 of 5 subunits of the superoxide-producing nicotinamide adenine dinucleotide phosphate oxidase of neutrophils, macrophages, and eosinophils. Allogeneic hematopoietic stem cell transplantation (HSCT) is currently the only curative treatment for CGD and can be offered to selected patients. Improved outcome with supportive care and high clinical variability in the disease course, however, make selection of eligible patients for HSCT difficult. This article addresses recent progress in HSCT for CGD, delineates present limitations, and points to future developments.

Haploidentical bone marrow transplantation in primary immune deficiency: stem cell selection and manipulation

Since the early 1980s T-cell depletion has allowed haploidentical bone marrow transplantation to be performed in patients with primary immunodeficiency for whom a matched sibling donor was not available, without causing severe graft versus host disease (GVHD). This review article presents the available data in the literature on survival, GVHD, and immune reconstitution in different categories of patients, with special emphasis on the impact of different T-cell depletion methods.

Transplantation of hematopoietic stem cells and long-term survival for primary immunodeficiencies in Europe: entering a new century, do we do better?

BACKGROUND

Hematopoietic stem cell transplantation remains the only treatment for most patients with severe combined immunodeficiencies (SCIDs) or other primary immunodeficiencies (non-SCID PIDs).

OBJECTIVE

To analyze the long-term outcome of patients with SCID and non-SCID PID from European centers treated between 1968 and 2005.

METHODS

The product-limit method estimated cumulative survival; the log-rank test compared survival between groups. A Cox proportional-hazard model evaluated the impact of independent predictors on patient survival.

RESULTS

In patients with SCID, survival with genoidentical donors (n = 25) from 2000 to 2005 was 90%. Survival using a mismatched relative (n = 96) has improved (66%), similar to that using an unrelated donor (n = 46; 69%; P = .005). Transplantation after year 1995, a younger age, B(+) phenotype, genoidentical and phenoidentical donors, absence of respiratory impairment, or viral infection before transplantation were associated with better prognosis on multivariate analysis. For non-SCID PID, in contrast with patients with SCID, we confirm that, in the 2000 to 2005 period, using an unrelated donor (n = 124) gave a 3-year survival rate similar to a genoidentical donor (n = 73), 79% for both. Survival was 76% in phenoidentical transplants (n = 23) and worse in mismatched related donor transplants (n = 47; 46%; P = .016).

CONCLUSION

This is the largest cohort study of such patients with the longest follow-up. Specific issues arise for different patient groups. Patients with B-SCID have worse survival than other patients with SCID, despite improvements in each group. For non-SCID PID, survival is worse than SCID, although more conditions are now treated. Individual disease categories now need to be analyzed so that disease-specific prognosis may be better understood and the best treatments planned.

A multiplex immunoassay using the Guthrie specimen to detect T-cell deficiencies including severe combined immunodeficiency disease

BACKGROUND

Severe combined immunodeficiency (SCID) fulfills many of the requirements for addition to a newborn screening panel. Two newborn screening SCID pilot studies are now underway using the T-cell receptor excision circle (TREC) assay, a molecular technique. Here we describe an immunoassay with CD3 as a marker for T cells and CD45 as a marker for total leukocytes that can be used with the Guthrie specimen.

METHODS

The multiplexing capabilities of the Luminex platform were used. Antibody pairs were used to capture and detect CD3 and CD45 from a single 3-mm punch of the Guthrie specimen. The assay for each biomarker was developed separately in identical buffers and then combined to create a multiplex assay.

RESULTS

Using calibrators made from known amounts of leukocytes, a detection limit of 0.25 x 10(6) cells/mL for CD3 and 0.125 x 10(6) cells/mL for CD45 was obtained. Affinity tests showed no cross-reactivity between the antibodies to CD3 and CD45. The multiplex assay was validated against 8 coded specimens of known clinical status and linked to results from the TREC assay that had identified them. All were correctly identified by the CD345 assay.

CONCLUSIONS

The performance parameters of the CD345 assay met the performance characteristics generally accepted for immunoassays. Our assay classifications of positive specimens concur with previous TREC results. This CD345 assay warrants evaluation as a viable alternative or complement to the TREC assay as a primary screening tool for detecting T-cell immunodeficiencies, including SCID, in Guthrie specimens.

Bioinformatics services related to diagnosis of primary immunodeficiencies

PURPOSE OF REVIEW

Most primary immunodeficiencies (PIDs) have overlapping signs and symptoms - presenting a challenge for diagnosis. The information available from the Internet for over 200 PIDs is scattered between numerous services and databases. Patient information has been collected in different patient registries. Several software tools have been developed in order to build the databases, expert systems and other information systems useful in diagnosis or prediction.

RECENT FINDINGS

Previously released services have been significantly improved and some new bioinformatics tools have been developed to help in diagnosis, prediction, mutation analysis and classification of PIDs. Several national initiatives have been launched for centralized PID information services. The very latest additions are tools and approaches for PID candidate gene prioritization, systematic classification and a medical expert system to help in diagnosis.

SUMMARY

Many bioinformatics tools for PIDs are already freely available over the Internet. We expect bioinformatics tools to further help healthcare professionals in diagnosis, analysis and prediction. Currently, most of the resources are stand-alone and thus their integration will be a challenge for the future. Another challenge is to develop terminologies, ontologies and standards to achieve semantic interoperability.

Update on gene therapy for immunodeficiencies

Primary immune deficiencies (PID) are due to blood cell defects and can be treated with transplantation of normal hematopoietic stem cells (HSC) from another person (allogeneic). Gene therapy in which a patient's autologous HSC are genetically corrected represents an alternative treatment for patients with PID, which could avoid the immunologic risks of allogeneic HSCT and confer similar benefits. Recent clinical trials using gene therapy have led to immune restoration in patients with X-linked severe combined immune deficiency (XSCID), adenosine deaminase (ADA)-deficient SCID and chronic granulomatous disease (CGD). However, severe complications arose in several of the patients in whom the integrated retroviral vectors led to leukoproliferative disorders. New approaches using safer integrating vectors or direct correction of the defective gene underlying the PID are being developed and may lead to safer and effective gene therapy for PID.