Th2 cell differentiation is decreased in Stat5a^−/− T cells.

Splenocytes from wild-type (WT) mice, Stat5a^−/− mice, or Stat5b^−/− mice were stimulated with platebound anti-CD3 mAb for 48 hours in nonpolarizing condition. 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 5 mice in each group.