Individually distinct tumor-specific cell surface antigen identified by monoclonal antibody on a Rous sarcoma virus-induced mouse tumor.

Hybrid cell lines were prepared by the fusion of BALB/c myeloma P3U-1 cells with the lymphocytes of BALB/c mice that were immunized with syngeneic Rous sarcoma virus (RSV)-induced tumor CSA1M cells. Three clones of the hybrid progeny (3.4B2, 3.4C6, and 3.5C11) produced cytotoxic IgM antibodies against CSA1M cells. One of the clones, 3.5C11, was chosen for analysis of the detailed specificity. Both direct cytotoxicity assays and absorption tests revealed that monoclonal antibody from 3.5C11 was positive only with CSA1M cells and that it failed to react with other tumors, including 20 RSV-induced mouse tumors, and normal cells. The 3.5C11 monoclonal antibody alone, with or without exogenous complement, was suppressive in the therapy of ip injected CSA1M tumor in syngeneic hosts, and significant prolongation in survival was seen in the treated mice. These results clearly showed presence of an individually distinct tumor-specific cell surface antigen on an RSV-induced mouse tumor.