Treatment of human melanoma hepatic metastases in nude mice with human cytotoxic T lymphocytes. We investigated the effects of human melanoma-specific cytotoxic T lymphocytes in treating experimental human melanoma hepatic metastases in a nude mouse model of adoptive immunotherapy. Hepatic metastases were generated by intrasplenic injection of 1.5 x 10(6) human melanoma cells. Three days after injection, animals received salt solution and interleukin 2 or interleukin 2 and cytotoxic T lymphocytes. Twenty-four of 25 control animals had developed multiple tumor nodules in the liver; 11 of 13 animals receiving only interleukin 2 also had significant tumor burdens. In striking contrast, 17 of 18 animals receiving cytotoxic T lymphocytes and interleukin 2 had no gross or histologic evidence of tumors. The remaining animal had a 2-mm nodule. Human tumor-specific cytotoxic T lymphocytes are effective in vivo in a model of adoptive immunotherapy and may prove useful in adoptive immunotherapy of humans with metastatic melanoma. 