The WASp-deficient B-cell phenotype is B cell–intrinsic. BM from WT or WASp^−/− mice was transplanted into sublethally irradiated μMT mice. Recipient mice were killed 6 weeks after transplantation, and B-cell subsets in BM, spleen, and peritoneal cavity were analyzed. Shown are absolute numbers for (A) BM (n = 9 recipient mice), (C) spleen (n = 7), and (D) peritoneal cavity (n = 7) and the relative percentage of subsets in (B) peripheral blood (n = 12).