Membrane antigens detected on human lung carcinoma cells by hybridoma monoclonal antibody

Hybridoma monoclonal antibodies were used to identify tumor cell membrane antigens on a new human lung carcinoma cell line. Hybridomas were constructed by fusing S194 mouse myeloma cells with lymphocytes from Balb/C mice immunized by the human carcinoma cell line UCLA-SO-P3. Of 768 hybridoma cultures tested 40 secreted antibody reacting with these P3 tumor cells by an indirect ¹²⁵I-protein A binding assay. Three produced antibody binding selectively to the P3 tumor cells, but not with a lymphoblastoid cell line from this same cancer patient. These 3 hybridomas were cloned by limiting dilution and antibody subclass was determined. The first monoclonal antibody reacted only with the P3 lung carcinoma and with one colon carcinoma line. The second cross-reacted with most human carcinomas tested including lung, colon, and breast carcinoma, but not with sarcomas, melanomas, embryonic cells, lymphoblastoid cells, or normal lymphocytes. The third reacted strongly with all the tumor cell lines tested except for sarcoma and with embryonic cells but not with lymphoblastoid cells or lymphocytes. These results show that monoclonal antibodies can be produced against a variety of different membrane antigens on this lung carcinoma cell line including several that may prove useful in diagnosis or treatment of human cancer.