Figure 1.

Blk is differentially expressed in immature and mature B cell subsets. (a) Histograms show representative staining of the i.c. levels of Blk in gated populations of immature and mature B cell subsets in the BM, spleen and PerC of C57BL/6 mice. In the BM, these subsets include pre-pro-B (IgM⁻ B220⁺ CD43⁺ c-Kit^lo), pro-B (IgM⁻ B220⁺ CD43⁺ c-Kit⁻), pre-B (IgM⁻ B220⁺ CD43⁻), and immature (IgM⁺ B220^lo) B cells. In the spleen, the subsets include T1 (B220⁺ CD93⁺ IgM^hi CD23⁻), T2 (B220⁺ CD93⁺ IgM^hi CD23⁺), T3 (B220⁺ CD93⁺ IgM^lo CD23⁺), FO-I (CD19⁺ IgD^hi IgM^lo CD21⁺), FO-II (CD19⁺ IgD^hi IgM^hi CD21⁺), MZP (CD19⁺ IgD^hi IgM^hi CD21^hi), and MZ (CD19⁺ IgD^lo IgM^hi CD21^hi) B cells. In the PerC, the subsets include B1a (IgM⁺ CD5^lo CD11b⁺), B1b (IgM⁺ CD5⁻ CD11b⁺) and B2 (IgM⁺ CD5⁻ CD11b⁻) B cells. Cells from all tissues were stained and acquired on the same day. Data are representative of two independent experiments, with 3 mice per experiment. Solid gray histograms represent Blk staining levels in mature CD4⁺ T cells, which express negligible levels of Blk by real-time RT-PCR analysis.⁷ (b) Summary of the data presented in a. Comparison of i.c. Blk levels, presented as mean fluorescence intensity values, in gated immature and mature B cell subsets.