Background CD27 is a lymphocyte costimulatory molecule that regulates T-cell, natural killer (NK) cell, B-cell, and plasma cell function, survival, and differentiation. On the basis of its function ...and expression pattern, we considered CD27 a candidate gene in patients with hypogammaglobulinemia. Objective We sought to describe the clinical and immunologic phenotypes of patients with genetic CD27 deficiency. Methods A molecular and extended immunologic analysis was performed on 2 patients lacking CD27 expression. Results We identified 2 brothers with a homozygous mutation in CD27 leading to absence of CD27 expression. Both patients had persistent symptomatic EBV viremia. The index patient was hypogammaglobulinemic, and immunoglobulin replacement therapy was initiated. His brother had aplastic anemia in the course of his EBV infection and died from fulminant gram-positive bacterial sepsis. Immunologically, lack of CD27 expression was associated with impaired T cell–dependent B-cell responses and T-cell dysfunction. Conclusion Our findings identify a role for CD27 in human subjects and suggest that this deficiency can explain particular cases of persistent symptomatic EBV viremia with hypogammaglobulinemia and impaired T cell–dependent antibody generation.
Background Primary immunodeficiency (PID) disorders are a heterogeneous group of inherited disorders caused by a variety of monogenetic immune defects. Thus far, mutations in more than 170 different ...genes causing PIDs have been described. A clear genotype-phenotype correlation is often not available, which makes a genetic diagnosis in patients with PIDs complex and laborious. Objective We sought to develop a robust, time-effective, and cost-effective diagnostic method to facilitate a genetic diagnosis in any of 170 known PID-related genes by using next-generation sequencing (NGS). Methods We used both targeted array-based and in-solution enrichment combined with a SOLiD sequencing platform and a bioinformatic pipeline developed in house to analyze genetic changes in the DNA of 41 patients with PIDs with known mutations and 26 patients with undiagnosed PIDs. Results This novel NGS-based method accurately detected point mutations (sensitivity and specificity >99% in covered regions) and exonic deletions (100% sensitivity and specificity). For the 170 genes of interest, the DNA coverage was greater than 20× in 90% to 95%. Nine PID-related genes proved not eligible for evaluation by using this NGS-based method because of inadequate coverage. The NGS method allowed us to make a genetic diagnosis in 4 of 26 patients who lacked a genetic diagnosis despite routine functional and genetic testing. Three of these patients proved to have an atypical presentation of previously described PIDs. Conclusion This novel NGS tool facilitates accurate simultaneous detection of mutations in 161 of 170 known PID-related genes. In addition, these analyses will generate more insight into genotype-phenotype correlations for the different PID disorders.
Abstract Background X-linked hyper IgM syndrome (XHIGM) is a primary immunodeficiency with high morbidity and mortality compared to normal individuals. Hematopoietic cell transplant (HCT) has been ...considered a curative therapy, but the procedure has inherent complications, and may not be available for all patients. Objectives We sought to collect data on the clinical presentation, treatment, and follow-up of a large sample of patients with XHIGM in order to (1) compare long-term overall survival and general well-being of patients treated with or without HCT along with clinical factors associated with mortality, and (2) summarize clinical practice and risk factors in the subgroup of patients treated with HCT. Methods Physicians caring for patients with primary immunodeficiency diseases were identified through the Jeffrey Modell Foundation, United States Immunodeficiency Network, Latin American Society for Immunodeficiency, and the Primary Immune Deficiency Treatment Consortium. Data was collected using a REDCap web application. Survival from time of diagnosis or transplant was estimated using the Kaplan-Meier method, compared using log-rank tests, and modeled using proportional hazards regression. Results Twenty-eight clinical sites provided data on 189 patients diagnosed with XHIGM between 1964 and 2013; 176 had valid follow-up and vital status information. Sixty-seven patients (38%) received HCT. The average follow-up time was 8.5 ± 7.2 years (range: 0.1-36.2 years). No difference in overall survival was observed between patients treated with or without HCT (p=0.671). However, risk associated with HCT decreased for diagnosis years 1987-1995; the hazard ratio was significantly < 1 for diagnosis years 1995-1999. Liver disease was a significant predictor of overall survival HR (95% CL): 4.9 (2.2, 10.8), p<0.001. Among survivors, those treated with HCT had higher median Lansky and Karnofsky scores than those treated without HCT (p<0.001). Among patients receiving HCT, 27 (40%) developed graft versus host disease, and most deaths occurred within 1 year of transplant. Conclusion No difference in survival was observed between patients treated with or without HCT across all diagnosis years 1964-2013. However, survivors treated with HCT experienced somewhat greater well-being and hazards associated with HCT decreased, reaching levels of significantly less risk, in the late 1990s. Among patients treated with HCT, treatment at an early age is associated with improved survival Optimism remains guarded as additional evidence accumulates.
Background The clinical and immunologic features of CD27 deficiency remain obscure because only a few patients have been identified to date. Objective We sought to identify novel mutations in TNFRSF7 .../ CD27 and to provide an overview of clinical, immunologic, and laboratory phenotypes in patients with CD27 deficiency. Methods Review of the medical records and molecular, genetic, and flow cytometric analyses of the patients and family members were performed. Treatment outcomes of previously described patients were followed up. Results In addition to the previously reported homozygous mutations c.G24A/p.W8X (n = 2) and c.G158A/p.C53Y (n = 8), 4 novel mutations were identified: homozygous missense c.G287A/p.C96Y (n = 4), homozygous missense c.C232T/p.R78W (n = 1), heterozygous nonsense c.C30A/p.C10X (n = 1), and compound heterozygous c.C319T/p.R107C-c.G24A/p.W8X (n = 1). EBV-associated lymphoproliferative disease/hemophagocytic lymphohistiocytosis, Hodgkin lymphoma, uveitis, and recurrent infections were the predominant clinical features. Expression of cell-surface and soluble CD27 was significantly reduced in patients and heterozygous family members. Immunoglobulin substitution therapy was administered in 5 of the newly diagnosed cases. Conclusion CD27 deficiency is potentially fatal and should be excluded in all cases of severe EBV infections to minimize diagnostic delay. Flow cytometric immunophenotyping offers a reliable initial test for CD27 deficiency. Determining the precise role of CD27 in immunity against EBV might provide a framework for new therapeutic concepts.
Background V(D)J recombination takes place during lymphocyte development to generate a large repertoire of T- and B-cell receptors. Mutations in recombination-activating gene 1 (RAG1) and RAG2 result ...in loss or reduction of V(D)J recombination. It is known that different mutations in RAG genes vary in residual recombinase activity and give rise to a broad spectrum of clinical phenotypes. Objective We sought to study the immunologic mechanisms causing the clinical spectrum of RAG deficiency. Methods We included 22 patients with similar RAG1 mutations (c.519delT or c.368_369delAA) resulting in N-terminal truncated RAG1 protein with residual recombination activity but presenting with different clinical phenotypes. We studied precursor B-cell development, immunoglobulin and T-cell receptor repertoire formation, receptor editing, and B- and T-cell numbers. Results Clinically, patients were divided into 3 main categories: T− B− severe combined immunodeficiency, Omenn syndrome, and combined immunodeficiency. All patients showed a block in the precursor B-cell development, low B- and T-cell numbers, normal immunoglobulin gene use, limited B- and T-cell repertoires, and slightly impaired receptor editing. Conclusion This study demonstrates that similar RAG mutations can result in similar immunobiological effects but different clinical phenotypes, indicating that the level of residual recombinase activity is not the only determinant for clinical outcome. We postulate a model in which the type and moment of antigenic pressure affect the clinical phenotypes of these patients.
...the most prevalent comorbidities in adult CVID are recurrent pneumonia (32%) and chronic lung disease (28%), with lung failure being the most prevalent cause of death.1 Pulmonary comorbidities ...include structural airway disease (AD) due to recurrent pulmonary infections and interstitial lung disease (ILD), in particular in patients with autoimmune phenomena.2 Both disease entities are well detected by high-resolution computed tomography (CT).2,3 In this study, we investigated progression of pulmonary disease in pediatric and in adult CVID patients in a 3- to 5-year follow-up period using a uniform CT scanning and scoring protocol.4,5 Pediatric and adult CVID patients were allocated to low- or high-risk profiles for AD and/or ILD disease progression. In support of the increased AD scores, we found that the AD score progression correlated to a decrease in predicted FEV1/forced vital capacity percentage (FVC%), although still within normal range in the group with low AD scores at baseline (r = −0.6; P = .048) (see Fig E1 in this article's Online Repository at www.jacionline.org). ...the AD score increase could not be predicted by upper or lower respiratory tract infection episodes or by abnormal PFTs. Because no radiologically proven pneumonias occurred during follow-up time and immunological phenotypes were normal in most cases in this group, we explored whether treatment parameters influenced AD score progression. Low-risk children High-risk children High-risk adults Total AB prophylaxis Continuous use 4/19 (21) 6/13 (46) 1/23 (4) 11/55 (20) Stopped during FU 9/19 (47) 5/13 (39) 7/23 (30) 21/55 (38) None 6/19 (32) 2/13 (15) 15/23...
Background Genome-wide association studies have shown a pattern of rare copy number variations and single nucleotide polymorphisms in patients with common variable immunodeficiency disorder (CVID), ...which was recognizable by a support vector machine (SVM) algorithm. However, rare monogenic causes of CVID might lack such a genetic fingerprint. Objective We sought to identify a unique monogenic cause of familial immunodeficiency and evaluate the use of SVM to identify patients with possible monogenic disorders. Methods A family with multiple members with a diagnosis of CVID was screened by using whole-exome sequencing. The proband and other subjects with mutations associated with CVID-like phenotypes were screened through the SVM algorithm from our recent CVID genome-wide association study. RT-PCR, protein immunoblots, and in vitro plasmablast differentiation assays were performed on patient and control EBV lymphoblastoids cell lines. Results Exome sequencing identified a novel heterozygous mutation in IRF2BP2 (c.1652G>A:p.S551N) in affected family members. Transduction of the mutant gene into control human B cells decreased production of plasmablasts in vitro , and IRF2BP2 transcripts and protein expression were increased in proband versus control EBV-immortalized lymphoblastoid cell lines. The SVM algorithm categorized the proband and subjects with other immunodeficiency-associated gene variants in TACI , BAFFR , ICOS , CD21 , LRBA , and CD27 as genetically dissimilar from polygenic CVID. Conclusion A novel IRFBP2 mutation was identified in a family with autosomal dominant CVID. Transduction experiments suggest that the mutant protein has an effect on B-cell differentiation and is likely a monogenic cause of the family's CVID phenotype. Successful grouping by the SVM algorithm suggests that our family and other subjects with rare immunodeficiency disorders cluster separately and lack the genetic pattern present in polygenic CVID cases.
Background Common variable immunodeficiency (CVID) is usually well controlled with immunoglobulin substitution and immunomodulatory drugs. A subgroup of patients has a complicated disease course with ...high mortality. For these patients, investigation of more invasive, potentially curative treatments, such as allogeneic hematopoietic stem cell transplantation (HSCT), is warranted. Objective We sought to define the outcomes of HSCT for patients with CVID. Methods Retrospective data were collected from 14 centers worldwide on patients with CVID receiving HSCT between 1993 and 2012. Results Twenty-five patients with CVID, which was defined according to international criteria, aged 8 to 50 years at the time of transplantation were included in the study. The indication for HSCT was immunologic dysregulation in the majority of patients. The overall survival rate was 48%, and the survival rate for patients undergoing transplantation for lymphoma was 83%. The major causes of death were treatment-refractory graft-versus-host disease accompanied by poor immune reconstitution and infectious complications. Immunoglobulin substitution was stopped in 50% of surviving patients. In 92% of surviving patients, the condition constituting the indication for HSCT resolved. Conclusion This multicenter study demonstrated that HSCT in patients with CVID was beneficial in most surviving patients; however, there was a high mortality associated with the procedure. Therefore this therapeutic approach should only be considered in carefully selected patients in whom there has been extensive characterization of the immunologic and/or genetic defect underlying the CVID diagnosis. Criteria for patient selection, refinement of the transplantation protocol, and timing are needed for an improved outcome.
Background B cells of patients with common variable immunodeficiency (CVID) disorders display impairment in production of immunoglobulin class-switched antibodies, which is possibly contributed to by ...defects in early B-cell activation. On resting B cells, B-cell receptors (BCRs) are organized in oligomers that are signaling inactive. Their triggering by cognate antigen causes the lateral reorganization of BCRs and associated proteins into signalosomes, resulting in BCR-activated calcium entry. In resting cells the B-cell surface antigen CD20 is associated with the BCR but dissociates on signalosome formation. Objective We sought to determine whether CD20 dissociation from the BCR during early B-cell activation might contribute to the development of CVID disorders. Methods We evaluated BCR signalosome formation, internalization, and signaling in primary B cells of pediatric patients with CVID disorders and healthy control subjects. Results In many pediatric patients with CVID disorders, B cells exhibit significant deficits in BCR triggering–mediated calcium entry in the cytosol, which correlates with impaired plasmablast differentiation in vitro . These alterations did not originate from upregulation of CD22 or defects in calcium channels and did not involve gene mutations in phospholipase Cγ2 or Bruton tyrosine kinase. Instead, B cells from patients with CVID disorders exhibited reduced BCR dissociation from CD20. BCR or CD20 cross-linking induced less BCR internalization, and antibody-mediated CD20 triggering elicited less BCR downstream signaling, as measured based on secondary fluxes. Conclusions We propose that CD20 dissociation from the BCR signalosome is pivotal to BCR-mediated calcium mobilization in the cytosol. Defects in CD20/BCR signalosome conformation might predispose to the spectrum of CVID disorders.
Background Adenosine deaminase (ADA) deficiency causes severe cellular and humoral immune defects and dysregulation because of metabolic toxicity. Alterations in B-cell development and function have ...been poorly studied. Enzyme replacement therapy (ERT) and hematopoietic stem cell (HSC) gene therapy (GT) are therapeutic options for patients lacking a suitable bone marrow (BM) transplant donor. Objective We sought to study alterations in B-cell development in ADA-deficient patients and investigate the ability of ERT and HSC-GT to restore normal B-cell differentiation and function. Methods Flow cytometry was used to characterize B-cell development in BM and the periphery. The percentage of gene-corrected B cells was measured by using quantitative PCR. B cells were assessed for their capacity to proliferate and release IgM after stimulation. Results Despite the severe peripheral B-cell lymphopenia, patients with ADA-deficient severe combined immunodeficiency showed a partial block in central BM development. Treatment with ERT or HSC-GT reverted most BM alterations, but ERT led to immature B-cell expansion. In the periphery transitional B cells accumulated under ERT, and the defect in maturation persisted long-term. HSC-GT led to a progressive improvement in B-cell numbers and development, along with increased levels of gene correction. The strongest selective advantage for ADA-transduced cells occurred at the transition from immature to naive cells. B-cell proliferative responses and differentiation to immunoglobulin secreting IgM after B-cell receptor and Toll-like receptor triggering were severely impaired after ERT and improved significantly after HSC-GT. Conclusions ADA-deficient patients show specific defects in B-cell development and functions that are differently corrected after ERT and HSC-GT.
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