A,B, Flow cytometry analysis of splenic B cell maturation in b12HL and b12H mice. A, Analysis of CD23 and CD21 expression. Plots shown were gated on B220+ (WT) or JRFL+B220+ (b12HL and b12H). Boxes define CD21+CD23+ follicular B cells and CD21++ marginal zone B cells. B, CD93 expression levels on b12HL and b12H CD23+CD21+ B cells (Upper box from A). C, Calcium mobilization analysis of gated splenic B cells of the indicated genotypes upon stimulation with anti-Igκ or soluble Env trimers. Data shown in A and B are representative of at least 6 mice analyzed in three experiments. Data in C are representative of three experiments.