T-bet controls the maintenance and differentiation potential of flu-induced effector memory B cells

Abstract

Abstract Although the transcription factor (TF) T-bet is expressed by antigen-experienced human B cells, including the extrafollicular IgD negCD27 negmemory-like DN2 cells and the IgD negCD27 +effector memory cells (eBmem), it is unknown whether T-bet expression influences the development, maintenance, or function of Bmem cells. Using oligo-labeled recombinant influenza nucleoprotein (NP) tetramers and paired single cell RNA and V(D)J sequencing, we characterized NP-specific Bmem in the draining LN of flu-infected memory mice. We identified 7 transcriptionally distinct clusters of mature non-replicating β Bmem cells. While none of the Bmem clusters expressed TFs required for plasma cell (PC) lineage commitment, one cluster, containing clonally-expanded somatically-mutated Bmem cells, expressed significantly higher levels of the T-bet gene, Tbx21, and was transcriptionally very similar to human T-bet +eBmem. The NP +Tbx21 +Bmem upregulated gene networks associated with metabolic reprogramming, protein synthesis and the mTOR-dependent unfolded protein response, suggesting that these cells might represent Bmem that are metabolically poised for rapid PC differentiation. Using constitutive and inducible models to delete Tbx21 specifically in B cells we showed that the rapid differentiation potential of Bmem is controlled by T-bet and that T-bet is required for the development and persistence of NP +eBmem subsets in LN and lung. Thus T-bet not only marks Bmem with effector potential but also regulates the persistence and function of flu-induced NP +Bmem that are transcriptionally poised to provide rapid humoral protection from infection. Supported by a grant from the NIH (R01 AI110508)