| Abstract: | Lyt-1+, L3T4a+ autoreactive cloned T cells, producing lymphotoxin (LT) and interferon-gamma (IFN-gamma) in response to self-class II major histocompatibility complex antigen in vitro were examined for their anti-tumor effect in vivo against B16 melanomas. Without the aid of exogenous interleukin 2, the autoreactive T cells, when injected immediately and at an equal cell number into the site of s.c. inoculated B16 melanoma cells inhibited tumor growth in sublethally irradiated and nonirradiated syngeneic mice. The autoreactive T cells also induced regression of tumors established 3 days earlier. Normal spleen cells or class II-restricted cloned T cells specific for chicken gamma-globulin (CGG) had no inhibitory effect on tumor growth. A single injection of autoreactive T cells delayed tumor growth and prolonged the survival of mice that had received a lethal dose of B16 melanoma cells. The autoreactive T cells caused extensive necrosis at the injection site. A treatment regime consisting of two successive injections of anti-I-Ab monoclonal antibody 3JP prevented the inhibition of tumor growth, supporting the hypothesis that the autoreactive T cells inhibited the growth of melanomas by releasing LT and IFN-gamma upon recognition of I-A antigen-bearing cells at the injection site. The CGG-specific control T cells did not cause necrosis and survived within the nests of uninhibited tumor cells. Autoreactive T cells administered i.v. immediately after i.v. injection of B16 melanoma cells markedly reduced pulmonary metastases, whereas CGG-specific T cells did not. These results indicate that autoreactive T cells can function in vivo as inhibitors of tumor growth. |
