EXPRESSION OF TUMOR ASSOCIATED ANTIGENS BY A PRODUCER AND A NONPRODUCER LEUKEMIA INDUCED BY RAUSCHER VIRUS (R-MULV)

Two Rauscher virus (R-MuLV)-induced leukemias, RBL-5, a virus-producer, and RBL-3, a nonproducer, were compared for their expression of cell surface antigens (RCSA), by cytotoxicity, membrane immunofluorescence, R-MuLV neutralization, and complement-fixation assays using syngeneic anti-crude membrane sera as well as anti-gp69/71, anti-p30, and anti-R-MuLV sera. There was a higher concentration of gp69/71 and p30 on the RBL-3 membrane than on RBL-5. This presumably is due to a cellular block at a step before assembly of virus, resulting in accumulation of these viral structural proteins (VSP). The common antigen on RBL-3 and RBL-5 is called RCSAa and may be composed of gp69/71 (RCSAa1) and an unidentified antigen (RCSAa2) which reacts more effectively with syngeneic antisera than against anti-VSP sera. An antigen abundant on the membrane of RBL-3 but not on RBL-5 is designated RCSAb, which is probably identical with p30. An unidentified antigen designated RCSAc is present on RBL-5, but not on RBL-3. Ascites cells of both RBL-3 and RBL-5 exhibited less RCSA than did the cultured lines. © 1979.