Immunological characteristics of monoclonal antibodies against human carcinoembryonic antigen (CEA).

Four hybridomas secreting monoclonal antibodies (MAbs) of the IgG1 subclass against human carcinoembryonic antigen (CEA) were obtained from fusion of P3-NS1/1-Ag4 myeloma cells with splenic cells from mice immunized with purified CEA. None of the MAbs showed cross-reactivity to perchloric acid extractable antigens from the normal human colon by an inhibition radioimmunoassay. However, MAb C27 showed the highest affinity to CEA. The intensity of immunofluorescence staining of human colorectal cancer cells with MAb C27 correlates well to the cellular CEA content of cancer cells. LS174T showed the highest intensity of fluorescence (95%) while COLO320DM and COLO320HRS were the lowest (0.5%). None of the normal human organs - colon, lungs, liver, spleen or kidneys-showed positive staining by immunoperoxidase anti-peroxidase (PA) techniques, while tissues from colorectal carcinoma (CRC), gastric carcinoma, hepatoma and lung cancer gave a positive rate of 100% (30/30), 96.6% (28/29), 32.1% (9/28) and 82.1% (69/84) respectively. Results suggest that MAb C27 can be used in immunodetection and radiolocalization of colorectal carcinoma.