STRUCTURE AND FUNCTION OF THREE NOVEL MHC CLASS I ANTIGENS DERIVED FROM A C3H ULTRAVIOLET-INDUCED FIBROSARCOMA

The class I antigens encoded within the MHC of the mouse are cell surface glycoproteins that play an essential role in immune recognition and regulation. CTL exhibit an absolute requirement for associated recognition of foreign antigens in the context of self MHC components (1). In addition, CTL can recognize non-self MHC molecules. This specific recognition of non-self MHC, known as allorecognition, is the cellular basis of the well known phenomenon of allograft rejection. Class I antigens also appear to be involved in the immune elimination ofcertain tumors (2, 3). Many tumors are highly immunogenic and are rejected when transplanted into normal, histocompatible mice (2-6). The ability of such tumors to arise in the autochthonous host might therefore represent the consequence of a compromised immune system that cannot limit neoplastic progression. In fact, many carcinogenic treatments, such as UV irradiation, are also immunosuppres-sive (5), and this might contribute to the outgrowth of otherwise immunogenic neoplastic cells. Consequently, ^-75 % of the tumors that arise in UV-treated mic