Immune response to ultraviolet-induced tumors. I. Transplantation immunity developing in syngeneic mice in response to progressor ultraviolet-induced tumors.

Ultraviolet-light-induced murine skin tumors were analyzed for the ability to induce transplantation immunity and cytotoxic lymphocytes in syngeneic mice. A correlation was found between tumor regression and the induction of cytotoxic T cells with specificity for a unique tumor-associated antigen. Processing tumors possessed tumor-associated transplantation antigens (TATA), which could be demonstrated by transplantation in hyperimmunized mice. Progression correlated with a lack of splenic cytotoxic T cell reactivity. High levels of in situ cytotoxic reactivity could be induced by presenting the tumor-specific antigen on nongrowing tumor cells. Tumor-bearer hosts were shown to be sensitized to TATA because cultured tumor-bearer T cells adoptively transferred protection against tumor outgrowth. Mechanisms of the in vivo suppression of antitumor immunity are discussed.