Figure 2. Elevated B cell apoptosis in Sost^−/− mice.

(A) FCM plots showing B cell developmental stages from bone marrow. The left panel shows the gating strategy for B cell “precursors” (which includes pre/pro-, pro- and pre-B cells combined), immature and recirculating B cell populations. The middle and the right panels represent staining from the Sost^+/+ and Sost^−/− mice, respectively. (B) Representative analysis of apoptosis by FCM in “precursor” B cells, as measured by staining with Annexin-V and 7-AAD. Live (Annexin-V^neg, 7-AAD^neg), early apoptotic (Annexin-V^pos, 7-AAD^neg) and combined late apoptotic and dead (Annexin-V^pos, 7-AAD^pos) B cells are discriminated. (C) Total percentages of “precursors” (B220^pos, IgM^neg) (left panel), immature (B220^pos, IgM^pos) (middle panel) and recirculating (B220^hi, IgM^pos) (right panel) B cells in Sost^+/+ (n=8) and Sost^−/− (n=10) mice. (D) Total percentages of Annexin-V^pos, 7-AAD^pos ”pre-cursor” (left panel), immature (middle panel) and recirculating (right panel) B cells in Sost^+/+ and Sost^−/− bone marrow. Data are representative of Sost^+/+ (n=4) and Sost^−/− (n=3) that are of pooled sexes and 12 to 15 weeks of age. Mean ± SD are shown, and all data were considered to be statistically significant if p < 0.05, two-tailed Student’s T-test.