The quantity of CD40 signaling determines the differentiation of B cells into functionally distinct memory cell subsets.

Koike, Takuya; Harada, Koshi; Horiuchi, Shu; Kitamura, Daisuke · Elife · 2019

basic_science · Level V

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Abstract

In mice, memory B (B<sub>mem</sub>) cells can be divided into two subpopulations: CD80<sup>hi</sup> B<sub>mem</sub> cells, which preferentially differentiate into plasma cells; and CD80<sup>lo</sup> B<sub>mem</sub> cells, which become germinal center (GC) B cells during a recall response. We demonstrate that these distinct responses can be B-cell-intrinsic and essentially independent of B-cell receptor (BCR) isotypes. Furthermore, we find that the development of CD80<sup>hi</sup> B<sub>mem</sub> cells in the primary immune response requires follicular helper T cells, a relatively strong CD40 signal and a high-affinity BCR on B cells, whereas the development of CD80<sup>lo</sup> B<sub>mem</sub> cells does not. Quantitative differences in CD40 stimulation were enough to recapitulate the distinct B cell fate decisions in an in vitro culture system. The quantity of CD40 signaling appears to be translated into NF-κB activation, followed by BATF upregulation that promotes B<sub>mem</sub> cell differentiation from GC B cells.

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