IL17A and colitis: In contrast, we have previously demonstrated that IL-17/IFN-γ double-positive T cells isolated from the large intestine of H. hepaticus-infected colitic mice are able to induce colitis upon transfer to H. hepaticus-infected Rag2−/− mice (16), indicating that ex vivo IL-17/IFN-γ double-producing lymphocytes isolated from Tbet-sufficient mice can induce intestinal pathology.