Cell type–specific contributions of Puma and Bim to glucocorticoid-induced apoptosis of immature and mature lymphocytes in vivo. Animals of the indicated genotypes were injected intraperitoneally with graded doses of dexamethasone and killed 20 hours later. Spleens and bone marrow were harvested, and single-cell suspensions were counted and stained with various fluorescence-conjugated cell surface marker–specific antibodies and analyzed in a flow cytometer. Total numbers of mature CD4⁺ T cells (A) and CD8⁺ T cells (B) from spleens of saline or dexamethasone-injected animals. (C) Total cellularity of B220⁺sIgM^-CD43^- pre-B cells in both femora of untreated or dexamethasone-treated animals. Bars represent means ± SE of 3 to 6 animals of each genotype and treatment regimen used from at least 3 independent experiments. Statistically significant differences are as follows: (A) CD4⁺ T cells: wt versus Puma^-/- (P < .049); wt versus vav-BCL2 (P < .008); (B) CD8⁺ T cells: wt versus Puma^-/- (P < .035), wt versus vav-BCL2 (P < .007); (C) B220⁺IgM^-CD43^- pre B cells: wt versus Bim^-/- (P < .022).