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Sci Rep. 2016 Oct 20;6:35673. doi: 10.1038/srep35673.

Antigen-affinity controls pre-germinal center B cell selection by promoting Mcl-1 induction through BAFF receptor signaling.

Author information

1
Department of Experimental Immunology, Academic Medical Center, 1105AZ, Amsterdam, The Netherlands.
2
Immunology Division, Garvan Institute of Medical Research, NSW 2010, Darlinghurst, Australia.

Abstract

Upon antigen encounter, the responsive B cell pool undergoes stringent selection which eliminates cells with low B cell receptor (BCR) affinity. Already before formation of the germinal center, activated B cells of low-affinity are negatively selected in a process that is molecularly not well understood. In this study, we investigated the mechanism behind pre-GC affinity-mediated B cell selection. We applied affinity mutants of HEL antigen and found that rapidly after activation B cells become highly dependent on the cytokine BAFF. Moreover, expression of BAFF receptor CD268 is regulated in a BCR-affinity dependent fashion. High affinity responses via BAFF correlated with PI3K activation, which controlled expression of the pro-survival protein Mcl-1, and thereby increased survival. In the presence of excess BAFF, or in absence of the Mcl-1 antagonist Noxa, more low-affinity B cells survived the first two days after antigen encounter. This resulted in increased numbers of antigen-specific B cells of low affinity upon immunization and reduced the overall affinity of cells that contributed to the germinal center reaction. Our findings elucidate a crucial molecular pathway of B cell selection in the earliest phases of activation by identifying a novel link between BCR affinity and BAFF-R signaling towards Mcl-1.

PMID:
27762293
PMCID:
PMC5071843
DOI:
10.1038/srep35673
[Indexed for MEDLINE]
Free PMC Article

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