Impaired B cell maturation in the bone marrow of SIRPα-mutant mice.

<p>(A) Absolute number of B220⁺ B cells in BM of 12 weeks old wild-type (open bar) or SIRPα-mutant mice (black bar). Data are means±SEM for 9 mice/group. (B) Representative flow cytometry analyses of BM B cell maturation based on expression of IgD and IgM in B220⁺ BM cells of wild-type or SIRPα-mutant mice. (C) Absolute numbers, or (D) relative numbers, of IgD^-IgM⁺ immature (Imm B), IgD^loIgM^hi transitional 1 (T1), IgD⁺IgM^hi follicular type-II (F-II) and IgD⁺IgM^lo follicular type-I (F-I) B cells in BM of 12 weeks old wild-type (open bars) or SIRPα-mutant mice (black bars). Data are means±SEM for 9 mice/group. (E) The relative expression of BIM protein, and (F) the relative increase in annexin V⁺ apoptotic cells, were quantified among BM B cell subsets defined as described in panels C-D. Data are means±SEM for 5 mice/group. *P<0.05, **P<0.01 and ***P<0.001, using Student’s t-test for unpaired analyses.