Solubilized TSTA and the major viral structural proteins, gp70 and p30, in the immune response to murine leukemias induced by Friend and Rauscher virus.

Antigens present in gp70 and p30 purified from Rauscher virus, were tested for immunogenicity in various assays measuring the anti-tumor immune response against lymphocytic leukemias of Friend (FBL-3) or Rauscher (RBL-5) virus origin. p30 had no effect on in vitro cytotoxicity against tumor cell targets mediated by either an anti RBL-5 serum or lymphocytes from animals immunized with FBL-3 cells. gp70 had had no effect on serum-mediated cytotoxicity but used at high concentrations it inhibited cell-mediated cytotoxicity. When used to immunize mice directly against subsequent challenge with the RBL-5 and FBL-3 leukemias, p30 had no discernible effect, while gp70 afforded partial protection against RBL-5 but only at high concentrations. Cell-free preparations of tumor membranes containing negligible amounts of gp70 were antigenically superior to gp70 in both the in vitro and in vivo assays. It is concluded that antigens on these purified proteins that are also expressed on tumor cells are not major targets of the anti-tumor immune response in this system.