Figure 3.

IL-1 synergizes with IL-23 to promote IL-17 production by spleen cells and purified CD4⁺ and CD8⁺ T cells. (A) Spleen cells (10⁶ cells/ml) from C57BL/6 or IL-1RI^−/− mice were cultured with 100 pg/ml IL-23 alone or together with 1 ng/ml IL-1α, and supernatants were collected after 3 d for analysis of IL-17 and IFN-γ by ELISA. C57BL/6 versus IL-1RI^−/−: *, P < 0.05; **, P < 0.01; ***, P < 0.001. IL-1α plus IL-23 versus IL-23; #, P < 0.001. (B) Spleen cells (2.25 × 10⁶ cells/ml) from C57BL/6 mice were cultured for 48 h with medium or cytokines and for the last 4 h in the presence of 10 μg/ml brefeldin A. Intracellular staining for IL-17 and IFN-γ was performed. Percentages refer to IL-17 production by gated CD3⁺ T cells. Splenic CD4⁺ (C) and CD8⁺ (D) T cells (5 × 10⁵cells/ml) from C57BL/6 mice were incubated with 10 U/ml IL-2 and 1 μg/ml anti-CD3 antibody alone or together with 0.1–1 ng/ml IL-23 and/or 1 ng/ml IL-1α or IL-1β. IL-17 concentrations were measured by ELISA in supernatants collected after 3 d. IL-23 plus IL-1 versus IL-23 only: *, P < 0.05; **, P < 0.01; ***, P < 0.001.