Flow cytometric analysis of B-lymphoid cell populations in the spleen. (A) Gated B220⁺ spleen cells analyzed for IgM and IgD expression. The total numbers of B220⁺ IgM^- IgD^- cells per spleen were 7.1, 20, and 170 × 10⁶ for the C57BL/6, Eμ-Bcl2 22, and VavP-Bcl2 69 mice, respectively. (B) Quantification of B-lymphoid cell populations in C57BL/6 and VavP-Bcl2 spleen (n = 4 for each strain).