Figure 3. TGF-β, IL-1β and IL-6, IL-21 or IL-23 are required for human T_H-17 cell polarization in serum-free conditions.

(a) Naive cord blood CD4⁺ T cells were activated without cytokines or with IL-1β, IL-6 or IL-21 with or without IL-23, alone or with increasing concentrations of TGF-β. IL-2 was added at day 3 and IL-17 expression was analyzed at day 14. (b) Naive cord blood CD4⁺ T cells were activated with no cytokine or with a combination of IL-1β + IL-23 + TGF-β (1 ng/ml), with or without 10 U/ml IL-2 or neutralizing anti-IL-2. IL-17 expression was analyzed at day 6. (c) Naive cord blood CD4⁺ T cells were cultivated with IL-2 and different concentrations of TGF-β in the presence of the listed cytokines. IL-17 expression was analyzed at day 6. (d) Time-course of IL-17 and IFN-γ production in naive cord blood CD4⁺ T cells polarized in the presence of IL-2 + IL-1β + IL-23 + TGF-β (0.1, 1 or 10 ng/ml). (e) Summary of IL-17 expression in day 6 cultures of naive cord blood CD4⁺ T cells from different donors (n = 11) in the presence of IL-2 + IL-1β + IL-23 + 10 ng/ml TGF-β. (f) Naive cord blood CD4⁺ T cells were cultivated in IL-2 alone or IL-23 + IL-1β + IL-2 with increasing concentrations of TGF-β. IL-17 and IL-22 expression were analyzed at day 6. Each panel is representative of at least three independent donors.