Blockade of IL-12/IL-23 blocks the expansion of Th1/Th17 cells. (A–C) LN cells from immunized WT (white bars) or p55 TNFR^−/− (gray bars) mice treated with control Ig (Ig) or rat anti–mouse p40 Ab (p40) were either unstimulated or stimulated with collagen or anti-CD3 mAb. Levels of IL-17 (A) and IFNγ (B) were determined by ELISA, and the proportion of CD4⁺ cells in the LN producing IL-17 and IFNγ were determined by flow cytometry (C). Histograms show mean ± SEM (n = 5). *, P < 0.05; **, P < 0.01; ***, P < 0.001. Data are representative of two experiments.