Defect in early B lymphopoiesis of transgenic mice.

(A) Phenotypic analysis of BM B cells stained with anti-B220–FITC and anti-CD19–PE monoclonal antibodies. The percentages of marked cells are indicated in the quadrants. (B) Reduction of B220⁺CD19⁺ IL-7Rα⁺ late pro-B cells in transgenic mice. Cells were stained with monoclonal anti-B220–FITC, anti-CD19–PE, and anti–IL-7Rα–biot/PE-Cy5. R2 represents the immature B220^low cells, and R3 comprises more mature BM B cells. B220^low CD19⁺ cells in R2 were further analyzed for FSC-height and IL-7Rα expression. (C) Reduction of B220⁺ c-kit⁺ IL-7Rα⁺ intermediate pro-B cells. Cells were stained with monoclonal anti-B220–FITC, anti–c-kit–APC, and anti–IL-7Rα–biot/PE-Cy5. B220⁺c-kit⁺ cells in R2 were further analyzed in a histogram plotting anti–IL-7Rα fluorochrome intensity against the relative number of IL-7Rα⁺ cells and shows the percentages of B220⁺ c-kit⁺ IL-7Rα⁺ cells in the lymphoid gate. These FACS analyses were repeated at least 5 times, and all percentages of Figure 3 refer to the lymphoid gates defined on forward and side light scatter.