The isolation and characterization of tumor-specific antigens of rodent and human tumors.

Putative tumor-specific transplantation antigens (TSTA) from both a carcinogen-induced rodent tumor (MC-1) and 2 human tumors were purified. The antigens were solubilized from the tumor cell membranes by limited papain digestion in a manner similar to that described for the isolation of normal histocompatibility antigens. The antitumor immune response of the tumor-bearing host was used to monitor the purification of the putative TSTA in both the rodent and human tumor systems. In the case of the rodent tumor, a major step in the purification of the TSTA involved affinity chromatography on Sepharose beads coupled to autologous antitumor antiserum. A comparable procedure was utilized in the purification of the TSTA from human tumors by using affinity chromatography on anti-human beta2-microglobulin antiserum coupled to a solid phase. The data obtained indicate that the TSTA of human tumors contains a beta2-microglobulin chain that is immunochemically identical with, and very similar in size to, that found in normal human histocompatibility antigens. A subunit of similar size was also identified in the carcinogen-induced rodent tumor. These results suggest that the TSTA in both humans and rodents may well be altered histocompatibility antigens.