Journal
JOURNAL OF ALLERGY AND CLINICAL IMMUNOLOGY
Volume 143, Issue 1, Pages 258-265Publisher
MOSBY-ELSEVIER
DOI: 10.1016/j.jaci.2018.06.012
Keywords
Common variable immunodeficiency; autoimmune cytopenias; germinal center responses; somatic hypermutation; B-cell tolerance; commensal bacteria; follicular helper T cell; regulatory T cell
Categories
Funding
- National Institutes of Health/National Institute of Allergy and Infectious Diseases (NIH/NIAID) [K23AI115001]
- Jeffrey Modell Foundation
- NIH/NIAID [AI-061093, AI-071087, AI-082713]
- NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES [R01AI071087, K23AI137183, K23AI115001, P01AI061093] Funding Source: NIH RePORTER
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Background: The lack of pathogen-protective, isotype-switched antibodies in patients with common variable immunodeficiency (CVID) suggests germinal center (GC) hypoplasia, yet a subset of patients with CVID is paradoxically affected by autoantibody-mediated autoimmune cytopenias (AICs) and lymphadenopathy. Objective: We sought to compare the physical characteristics and immunologic output of GC responses in patients with CVID with AIC (CVID+AIC) and without AIC (CVID-AIC). Methods: We analyzed GC size and shape in excisional lymph node biopsy specimens from 14 patients with CVID+AIC and 4 patients with CVID-AIC. Using paired peripheral blood samples, we determined how AICs specifically affected B-and T-cell compartments and antibody responses in patients with CVID. Results: We found that patients with CVID+AIC displayed irregularly shaped hyperplastic GCs, whereas GCs were scarce and small in patients with CVID-AIC. GC hyperplasia was also evidenced by an increase in numbers of circulating follicular helper T cells, which correlated with decreased regulatory T-cell frequencies and function. In addition, patients with CVID+AIC had serum endotoxemia associated with a dearth of isotype-switched memory B cells that displayed significantly lower somatic hypermutation frequencies than their counterparts with CVID-AIC. Moreover, IgG(+) B cells from patients with CVID+AIC expressed VH4-34-encoded antibodies with unmutated Ala-Val-Tyr and Asn-His-Ser motifs, which recognize both erythrocyte I/i self-antigens and commensal bacteria. Conclusions: Patients with CVID+AIC do not contain mucosal microbiota and exhibit hyperplastic yet inefficient GC responses that favor the production of untolerized IgG(+) B-cell clones that recognize both commensal bacteria and hematopoietic I/i self-antigens.
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