EVIDENCE FOR TWO FUNCTIONALLY DISTINCT CROSS-REACTIVE TUMOR ANTIGENS ASSOCIATED WITH ULTRAVIOLET LIGHT AND CHEMICALLY INDUCED TUMORS

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Abstract
The distribution and function of common tumor antigens shared by UV light, benzo[a]pyrene (BP)-, and methylcholanthrene (MCA)-induced tumors were studied. Cytotoxic T lymphocytes (CTL) from lymph nodes of tumor-immune mice were capable of lysing a battery of different tumor targets. These CTL seemed to recognize tumor-associated antigens (TAA) common to UV and chemically-induced tumors. Although these common TAA were recognized by CTL in vitro and in vivo, they were incapable of eliciting cross-protective tumor immunity when tumor immunizations and challenges were made entirely in vivo. The state of cross-protective immunity within hyperimmune mice is directed toward shared tumor-associated transplantation antigens (TATA) which are related to the induction etiology of the tumor. The suppressor T lymphocytes (Ts cells) present in UV-treated animals possess functional specificity for the common TATA expressed by UV tumors. UV-induced Ts cells were capable of blocking the reexpression of an in vivo state of cross-protective immunity between two MCA tumors that did not express UV tumor TATA; apparently these cells recognize the common TAA shared by UV and MCA tumors. Two classes of common tumor antigens are expressed by UV and chemically induced tumors: TATA and the common TAA. The shared TATA function in vivo as rejection antigens and are restricted to tumors induced by the same carcinogenic agent. The common TAA shared by UV and chemically induced tumors are recognized by CTL and function as immunoregulatory determinants. The importance of these common tumor antigens in host-tumor interactions is discussed.