We analyzed the functional role of CD8+ T-cell receptor (TCR) Vbeta14+ T cells, which increased specifically in the lamina propria in 2,4,6-trinitrobenzene sulfonic acid (TNBS) -induced colitis. Cytotoxic activity and cytokine production in CD8+ TCR Vbeta14+ T-cell clones were analyzed by 51Cr release assay and enzyme-linked immunosorbent assay, respectively. Cell transfer studies using these clones were performed. Established T-cell clones showed specific cytotoxic activity against TNBS-conjugated self spleen cells, and this cytotoxicity was completely inhibited by anti-TCR Vbeta14 monoclonal antibody. These clones produced interferon (IFN) - gamma in their culture supernatant, but neither interleukin (IL) - 2 nor IL-4. Histological findings of the colon in mice, which received clone transfer after enema with suboptimal doses of TNBS, showed massive colitis. Our results indicate that CD8+ TCR Vbeta14+ T cells had a cytotoxic T-lymphocyte function induced by Th-1 T-cell response and played a pathogenic role in the development of TNBS-induced colitis.