Flow cytometry analysis of bone marrow and spleen cells from wild type (WT) C57BL/6, IgM-tg and IgG-tg mice.

(A) Analysis of bone marrow cells. Cells were stained for B220, IgM, and CD43. Percentages of pro B cells (IgM⁻, B220⁺, CD43⁺), pre B cells (IgM⁻, B220⁺, CD43⁻), immature B cells (B220^lo, IgM^med), transitional B cells (B220⁺, IgM^hi), and mature B cells (B220^hi, IgM^med) are calculated. Numbers of mice analyzed are indicated, and data are shown as mean (±SD) (bottom). (B) Subsets of spleen B cells. Spleen cells were stained for CD3, B220, CD21 and CD23. Percentages of T cells and B cells (left panel) in total spleen cells, and those of MZ B cells (B220⁺, CD21^hi, CD23^lo/−) and follicular B cells (B220⁺, CD21^inter, CD23^hi) in total B cells (right panel) are calculated. Numbers of mice analyzed are indicated, and data are shown as mean (±SD) (bottom). (C) Expression of BCR on spleen B cells. Spleen cells were stained for NIP binding, IgG2a, IgM and B220. Mean fluorescence intensity (MFI) of NIP binding is indicated. (D) Expression of various molecules on spleen B cells. Spleen cells from IgG-tg (open histograms) and IgM-tg (shaded histograms) mice were analyzed for expression of CD40, CD22, CD19, MHC class II, CD86, CD44, CD23, Fas, and CD93. All histograms are gated on B220⁺ cells.