Strong reduction of mature cell types in Pax5 ^R31Q/E242 * and Pax5^R31Q/−mice. (A) Flow-cytometric analysis of total, MZ, and FO B cells in the spleen of nonimmunized Pax5^+/+, Pax5^+/−, Pax5^R31Q/−, and Pax5^R31Q/E242* mice. (B–E) Flow-cytometric analysis of the indicated B cell types in the spleen (B), lymph node (C), bone marrow (D), and peritoneal cavity (E) of nonimmunized mice of the indicated genotypes. Absolute cell numbers of total B, FO B, MZ B, B-1a, and conventional B-2 cells as well as plasma cells are shown as mean values with SEM (n ≥ 10 per genotype for B–E). The different B cell types were defined as shown in A, Fig. S1 E, and Materials and methods. (F) Titers of total IgG, IgA, and IgM antibodies in the serum of nonimmunized Pax5^+/+, Pax5^+/−, and Pax5^R31Q/− mice (8–10 wk). The antibody concentrations were determined by ELISA and are shown as mean values with SEM (n = 8 per genotype). ANOVA with Tukey’s, Dunnett’s or Dunnett’s T3 multiple comparisons test (B–F); *, P < 0.05; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001. For detailed statistical information (B–F), see Table S6. Each dot (B–F) corresponds to one mouse.