Tumor‐associated antigens of chemically‐induced murine tumors; the emergence of MuLV and fetal antigens after serial passage in culture

Using radioiodinated Staphylococcus aureus protein A [ 125 I]SPA to measure syngeneic, allogeneic and heterogeneic IgG bound to murine tumor cells, we performed a serological analysis of surface antigens of 8 solid tumors and 2 leukemias of BALB/c mice (3 chemically‐induced colon carcinomas, 3 chemically‐induced sarcomas, 1 murine leukemia virus (MuLV) induced leukemia, 1 irradiation Induced leukemia, 1 spontaneous melanoma and 1 spontaneous sarcoma). We were able to detect and distinguish between at least five separate antigenic specificities on these tumors. Unique tumor‐associated antigens were found on 3 of the tumors, MuLV related antigens on 8 tumors, fetal antigens on 7 tumors and two distinct common antigens on 7 tumors (common antigen 1 (CA‐1) on 5 tumors and common antigen 2 (CA‐2) on 2 tumors). Neither of the common antigens was found to be sarcoma, carcinoma or tissue‐type specific. A number of tumors which did not originally express either MuLV or fetal antigens in primary cultures expressed these antigens after several serial passages in vitro .