Development of Th2 cells from purified CD4⁺T cells is decreased in Stat5a^−/− mice.

Purified splenic CD4⁺ T cells from DO10⁺ mice (A,C,E) or DO10⁺Stat5a^−/− mice (B,D,F) were stimulated with platebound anti-CD3 mAb and anti-CD28 mAb for 48 hours in Th0-, Th1-, or Th2-polarizing condition. Activated T cells were cultured in the presence of IL-2 for another 3 days and then restimulated with platebound anti-CD3 mAb for 6 hours. Intracellular cytokine profiles for IL-4 versus IFN-γ were determined on CD4⁺ T cells as described in “Materials and methods.” Shown are representative FACS profiles from 4 mice in each group.