Flow cytometric analysis of cell-surface markers on transgenic (T) Jak3−/+ and Jak3−/− mice. Jak3−/− mice were crossed with a transgenic mouse expressing Jak3 under the control of the proximal Lck promoter, and splenocytes from transgenic Jak3+/− and Jak3−/− animals were analyzed as depicted in Fig 3. (A) Density plots of splenocytes depicting FSC and SSC scatter. Density plots of splenocytes stained with antibodies against FcγRII/III (vertical axis) versus Mac-1, Gr-1, and F4/80 (horizontal axes). (B) Density plots of splenocytes from transgenic Jak3+/− and Jak3−/− mice stained with antibodies against CD4 (vertical axis) and L-selectin (horizontal axis). Notice the lack of L-selectin high CD4-positive cells in the transgenic Jak3−/− animals. When CD4 cells are gated and analyzed for L-selectin expression, a shift of L-selectin high, CD4-positive cells in the Jak3+/− mice to L-selectin low, CD4-positive cells in the Jak3−/− mice is apparent.