B-cell populations in lymphoid organs. (A) Total numbers of B220⁺ B cells are less in KI spleens, LNs, and BM compared with WT. (B) The frequency of B220⁺ cells was reduced in spleens and BM of KI mice, but not LNs. (C) The relative sizes of B cells in the spleen and LN were smaller in KI mice. (D) The total number of CD138⁺ plasma cells was also less in the spleens of KI mice. (E) The frequency of CD138⁺ cells was reduced in spleens of KI mice. For all panels, N = 6 to 12; age, 8 to 9 weeks.