In:
Blood, American Society of Hematology, Vol. 124, No. 21 ( 2014-12-06), p. 1413-1413
Abstract:
Recently, we and others found that B cells differentiate into regulatory B cells (Breg) in response to interleukin (IL-)21. Of note, the key characteristic of human IL-21-induced Breg is expression of the serine protease granzyme B (GrB), whereas murine Breg, which require both IL-21 and CD40 ligand (CD40L) for their induction, predominantly express the immunosuppressive cytokine IL-10. Using two different disease models and various immunological methods, we further characterized the conditions leading to Breg differentiation in humans. Here, we demonstrate that in humans CD40L determines whether IL-21 induces differentiation of B cells into plasma cells (CD40L presence) or into GrB+ Breg (CD40L absence), which can directly control T cell proliferation by GrB-dependent degradation of the T cell receptor z-chain. Furthermore, we show that GrB+ Breg are circulating at high frequencies in the peripheral blood of untreated, highly viremic HIV patients, but not in healthy subjects. Of note, HIV-infected CD4+ T cells express IL-21, but not CD40L, and induce a GrB+ regulatory phenotype in healthy third party B cells in vitro. Consequently, addition of CD40L multimers can compensate for this insufficient T helper cell function, resulting in increased plasma cell/Breg ratios. Moreover, we investigated a patient with a congenital defect of Nuclear-Factor-kappa-B-Essential-Modulator (NEMO), which is essential for normal CD40 signaling. Even in the presence of viral infections, when CD4+ T helper cells from such patients are highly activated with strong expression of IL-21, they are not able to establish sufficient antibody responses. Instead, we found this patient to almost exclusively harbor B cells with a regulatory phenotype including high basal levels of GrB. When untreated NEMO B cells were co-cultured with allogeneic T cells from a healthy third party donor, these T cells failed to proliferate and to survive in response to a 6-day stimulation with anti-CD3/CD28 antibodies, an effect not observed with B cells from healthy donors. Since NEMO B cells lack normal CD40 signaling, our findings unequivocally demonstrate that in contrast to murine Breg IL-21-dependent induction of human Breg can occur in a CD40-independent fashion. Disclosures No relevant conflicts of interest to declare.
Type of Medium:
Online Resource
ISSN:
0006-4971
,
1528-0020
DOI:
10.1182/blood.V124.21.1413.1413
Language:
English
Publisher:
American Society of Hematology
Publication Date:
2014
detail.hit.zdb_id:
1468538-3
detail.hit.zdb_id:
80069-7
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