The Transcription Factor T-bet Resolves Memory B Cell Subsets with Distinct Tissue Distributions and Antibody Specificities in Mice and Humans

B cell subsets expressing the transcription factor T-bet are associated with humoral immune responses and autoimmunity. Here, we examined the anatomic distribution, clonal relationships, and functional properties of T-bet+ and T-bet− memory B cells (MBCs) in the context of the influenza-specific immune response. In mice, both T-bet− and T-bet+ hemagglutinin (HA)-specific B cells arose in germinal centers, acquired memory B cell markers, and persisted indefinitely. Lineage tracing and IgH repertoire analyses revealed minimal interconversion between T-bet− and T-bet+ MBCs, and parabionts showed differential tissue residency and recirculation properties. T-bet+ MBCs could be subdivided into recirculating T-betlo MBCs and spleen-resident T-bethi MBCs. Human MBCs displayed similar features. Conditional gene deletion studies revealed that T-bet expression in B cells was required for nearly all HA stalk-specific IgG2c antibodies and for durable neutralizing titers to influenza. Thus, T-bet expression distinguishes MBC subsets that have profoundly different homing, residency, and functional properties, and mediate distinct aspects of humoral immune memory. [Display omitted] •T-bet+ B cells are a separate and durable memory subset in mice and humans•T-bethi memory B cells are absent from the lymphatic circulation•Influenza-specific T-bethi memory B cells are spleen-resident in mice•B cell-intrinsic T-bet is required for >90% of flu- and HA stalk-specific antibodies Johnson, Rosenthal, Knox, Myles, et al. find that differential T-bet expression marks subsets of memory B cells (MBCs) with distinct homing and tissue residency patterns and functional properties. Distinguishing features of T-bet−, T-bethi, and T-betlo MBCs are seen also in humans.