Figure 1.

IL-17 promotes tumor growth, which is mainly mediated by T cells. (A) 10⁵ B16 tumor cells were injected subcutaneously into WT, IL-17^−/−, IFN-γ^−/−, and IFN-γ^−/−IL-17^−/− B6 mice. Data represent means ± SEM (n = 12 mice per group from three independent experiments). (B) MB49 tumor growth in WT, IL-17^−/−, IFN-γ^−/−, and IFN-γ^−/−IL-17^−/− B6 mice (n = 8 mice from two experiments). (C and D) Intratumoral IL-17 promotes cancer metastasis. (C) MB49 tumor cells were injected subcutaneously into the four groups of mice as indicated, and lung colonies were enumerated 3 wk later (n = 4; P = 0.01). (D) Representative photos of the lung tissues from each group with arrows indicating lung metastasis are shown. Bars: (top) 1,000 µm; (bottom) 500 µm. (E) IL-17–mediated tumor-promoting effects are mainly mediated by T cells. Rapid B16 tumor growth in Rag-2^−/− mice receiving adoptive transfer of IFN-γ^−/− T cells was observed compared with significantly reduced growth rates in mice receiving adoptive-transferred IFN-γ^−/−IL-17^−/− T cells. Data represent means ± SEM (n = 11 mice from two experiments).