B cells diversify and affinity-mature their antigen receptor repertoire in germinal centers (GC). GC B cells receive help signals during transient interaction with T cells, yet it remains unknown how these transient T-B interactions sustain the subsequent proliferative program of selected B cells. Here we show that the transcription factor AP4 is required for sustained GC B cell proliferation and subsequent establishment of a diverse and protective antibody repertoire. AP4 is induced by c-MYC during the T-B interactions and maintained by T cell-derived IL-21. B cell-specific deletion of AP4 resulted in reduced GC sizes and somatic hypermutation and a failure to control chronic viral infection. These results indicate that AP4 integrates T cell-mediated selection and sustained expansion of GC B cells for humoral immunity. SOURCE: Takeshi Egawa (tegawa@wustl.edu) -  Washington University School of Medicine

Pluto Bioinformatics

GSE80669: Defining AP4- and MYC-regulated gene expression programs in germinal center B cells during cyclic re-entry