H–2 region product as determinant in immune cytolysis of syngeneic tumour cells by anti-MSV T lymphocytes

THE existence of cytolytic T lymphocytes (CTL) specific for antigenically related tumour cells during oncornavirus-induced oncogenesis in the primary host is well documented. They exist in murine sarcoma virus (MSV) tumour-bearing mice, during and after the tumour rejection 1 , and in Friend virus-infected mice, notably in the spleen of resistant C57BL/6 (ref. 2). It is probable that they play some role in tumour cell destruction in vivo 3 and it can be supposed that the antigens of the tumour cell surface recognised by CTL are at least, for the most part, viral proteins or glycoproteins. It was suggested that CTL reacting with virus producer cells in non-oncogenic systems 4 , or with hapten-modified cells 5,6 recognise an H–2-modified antigen. Therefore, it was of interest to determine whether the same situation exists in an oncornavirus tumour system. It is already known that anti-MSV CTL are much more efficient against syngeneic than against allogeneic tumour cells 7,8 , indicating that H–2 antigens may play some role in the CTL–target cell interaction. We report here that the H–2 specificities of the tumour cell surface determine the interaction with syngeneic anti-MSV CTL, the reacting antigen being either an H–2 specificity modified by the virus, or, less probably, a virus-induced antigen modified by an H–2 region product.