In vivo host immune to a tumor-specific transplantation antigen induced by Rous sarcoma virus

We examined the host immune response to a tumor-specific transplantation antigen (TSTA) induced by Rous sarcoma virus (RSV) In vivo. In contrast to previous in vitro studies, the present investigation demonstrated in vivo host immunity of the TSTA 10-55 days after tumor inoculation. Immunity to the TSTA appeared specific, since the homologous RSV tumor was rejected. whereas the heterologous tumor grew progressively. No generalized suppression of cell-mediated or hymoral immunity was shown, because tumor-bearing hosts retained the ability to reject heterologous tumor cells and mounted a normal plaque response to sheep red blood cells. Although alpha-globulin levels were elevated, they did not appear to affect the host's immunity to the growing tumor or to heterologous antigens. Assoicated with the progressively growing tumor was the appearance in the serum of a fetal antigen with characteristics of an alpha-2 acute phase protein.