Reduction in the number of B cells from the spleens and BM of KA/KA mice compared with WT mice. (A-C) Spleen sizes (A), spleen weights (B), and the number of B220⁺ cells from the spleens and BM (C) of WT (+/+), +/KA, and KA/KA mice at 4 weeks of age. Each group contained 3 mice. The data are presented as means ± SD. (D) Comparison of B cells (CD45R) and cell death (TUNEL staining) in the spleens and BM of WT and KA/KA mice. Brown indicates immunohistochemical-stained cells with an anti-CD45R Ab or TUNEL assay; blue, nuclear countering staining. Scale bar indicates 50 μm.