Myd88L252P promotes cell-intrinsic expansion of spontaneous splenic GCBs. (A) Experimental scheme for data in panels B to E. (B) Percentages of CD45.2 follicular B cells (FoB) and GCBs in unimmunized spleen of mixed BM chimeras generated as in panel A. Example gating strategy for FoB and GCBs is shown on left in panel B. (C) Ratio of frequency of CD45.2 GCBs to CD45.2 FoB in control or Cr2-creMyd88L252P/+ mixed BM chimeras in unimmunized spleen, SRBC-immunized pLNs, mesenteric lymph nodes (mLNs), and PPs. (D) Percentages of CD45.2 non-B cells (non-B), FoBs, GCBs, PCs, and marginal zone B cells (MZB) from mixed chimeras generated as in panel A. (E) Percentages of CD45.2 FoBs and IgM+ or IgM– GCBs in unimmunized spleen of mixed BM chimeras generated as in panel A. (F) GCBs or PCs per spleen of littermate or Cr2-cre Myd88L252P mice aged up to 1 year. Data in panels A to E are pooled from 2 independent experiments representative of 4 with 5 mice per group total. Data in panel F are from a total of 43 control and 28 Cr2-cre Myd88L252P animals. *P < .05, **P < .01, ***P < .001, **** P < .0001, unpaired two-tailed t test.