Tumor-specific antigens on rat liver cells transformed in vitro by chemical carcinogens

With the use of membrane immunofluorescence and xenogeneic antisera, tumor-specific membrane antigens were detected on rat epithelial-like liver cells transformed in vitro by chemical carcinogens. These antigens were not detected in 10-, 15-, and 19-day rat fetuses. Xenogeneic antisera were produced in rabbits by immunization of the rabbits with cultivated BD rat liver cells transformed by dimethylnitrosamine or N-methyl-N'-nitro-N-nitrosoguanidine. The specific antisera against tumor-associated antigen(s) were obtained by in vivo absorption in syngeneic male rats and by in vitro absorption with various cell lines. One tumor-specific individual antigen and two tumor-specific cross-reacting antigens were shown to be present on the surface of chemically and/or spontaneously transformed rat liver cell lines. They were not detected on liver and spleen cells of normal BD adult rats, on fetal liver cells, or on liver and intestinal carcinoma cells of Wistar rats. Sera from multiparous pregnant rats had no antibodies against these tumor antigens (although they reacted with fetal cells).