Retrovirus-mediated expression of Stat5b restores Th2 cell differentiation in Stat5a^−/−CD4⁺ T cells.

Purified splenic CD4⁺ T cells from DO10⁺Stat5a^−/− mice were stimulated with platebound anti-CD3 mAb and anti-CD28 mAb for 48 hours in Th2-polarizing condition. Activated T cells were then infected with retroviruses of pMX-Stat5a-IRES-GFP, pMX-Stat5b-IRES-GFP, or pMX-IRES-GFP (as a negative control) as described in “Materials and methods.” Cells were cultured with IL-2 for another 60 hours and then restimulated with platebound anti-CD3 antibody for 6 hours. Intracellular cytokine profiles for IL-4 versus IFN-γ were evaluated on infected CD4⁺ T cells (GFP⁺CD4⁺cells). Shown is representative intracellular cytokine staining from 4 independent experiments.