CD11c + B cells have been reported to be increased in autoimmune diseases, but they are detected in the blood of healthy individuals as well. We aimed to characterize CD11c + B cells from healthy donors by flow cytometry, microarray analysis, and in vitro functional assays. Here, we report that CD11c + B cells are a distinct subpopulation of B cells, enriched in the memory subpopulation even if their phenotype is heterogeneous, with overexpression of genes involved in B-cell activation and differentiation as well as in antigen presentation. Upon activation, CD11c + B cells can differentiate into antibody-secreting cells, and CD11c could be upregulated in CD11c − B cells by B-cell receptor activation. Finally, we show that patients with pemphigus, an autoimmune disease mediated by B cells, have a decreased frequency of CD11c + B cell after treatment, relative to baseline. Our findings show that CD11c + B cells are mainly memory B cells prone to differentiate into antibody secreting cells that accumulate with age, independently of gender.

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