cIAP1 and cIAP2 perform redundant functions to negatively regulate B-cell accumulation in vivo. (A) Flow cytometric analysis of lymph node cells (top) and splenic B cells (bottom) from the indicated mouse lines. Spleen samples are also gated on total B cells (B220⁺ gate). The window on lymph node data indicates mature B cells (B220⁺ gate). Windows on spleen data indicate, from left to right: immature (CD21/CD35^lo, CD23^lo), follicular (CD21/CD35^mid, CD23^hi), and marginal zone (CD21/CD35^hi, CD23^lo) B-cell populations. All numbers indicate the proportion of displayed events falling within the associated windows. (B) Enumeration of lymphocytes from the spleen and lymph nodes (pooled cervical, inguinal, axillary, brachial, and mesenteric nodes) of various mouse lines exhibiting the indicated lymphocyte phenotypes as determined by flow cytometry. Points represent data from individual mice; and lines, the arithmetic means. (C) Photograph showing spleen sizes from mice of the indicated genotypes. (D) CD21/CD35 expression levels on B cells from the lymph nodes of mice of the indicated genotypes. Flow cytometry data were gated on live lymphocytes by light scatter, then on B220⁺ B cells. All data were representative of at least 3 mice of each genotype.