In Vivo Host Immune Response to a Tumor-Specific Transplantation Antigen Induced by Rous Sarcoma Virus

Summary

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 to 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 humoral 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 α-globulin levels were elevated, they did not appear to affect the host's immunity to the growing tumor or to heterologous antigens. Associated with the progressively growing tumor was the appearance in the serum of a fetal antigen with characteristics of an α-2 acute phase protein.