Role of CD11c+ T-bet+ B cells in human health and disease

•Atypical memory B cells are CD27lo, CD21lo, CD11chi and express T-bet.•CD11c+ memory B cell frequency is increased in settings of chronic stimulation.•Atypical subset is enriched for autoreactive specificities, suggesting pathogenicity. A growing body of evidence suggests that when B cells are chronically stimulated, a phenotypically unique subset expands. Data suggest that this atypical population contains B cell receptor (BCR) specificities capable of binding the antigen, or sets of antigens that initiated the expansion of these cells. These B cells have been given various names, including double negative B cells, atypical memory B cells, tissue-like memory B cells, or age associated B cells (ABCs). However, on close inspection these reports described B cell subsets that closely resemble B cells we refer to as CD11c+ B cells that often express T-bet. Here we will review the human studies that describe atypical memory B cells and compare and contrast their phenotype and suggested function in health and disease.