IL-21 does not inhibit IL-4–induced Th2 cell differentiation.
(A) Splenocytes from DO10+ mice were stimulated with OVA323-339 peptide (50 μM; ▪) or OVA323-334 (50 μM; ■; as a control) for 72 hours in the presence or absence of IL-21 (10 ng/mL). The amounts of IL-4, IL-5, and IFN-γ in the supernatant were determined by ELISA. Data are mean ± SD from 5 independent experiments. (B) Splenocytes from DO10+ mice were stimulated with OVA323-339 peptide (50 μM) for 48 hours in the presence or absence of IL-21 (10 ng/mL) or sIL-21R (20 μg/mL). Where indicated, IL-12 (7.5 ng/mL) or IL-4 (7.5 ng/mL) was added to polarize toward Th1 cells (Th1 condition) or Th2 cells (Th2 condition), respectively. Cells were then cultured in the presence of IL-2 (5 ng/mL) for another 3 days. Intracellular staining for IL-4 and IFN-γ of CD4+ T cells was analyzed by fluorescence-activated cell-sorting (FACS). Shown are representative FACS profiles from 5 mice in each group.
