COMPARISON OF COLON‐, LUNG‐, AND BREAST‐DERIVED CARCINOEMBRYONIC ANTIGEN AND CROSS‐REACTING ANTIGENS BY MONOCLONAL ANTIBODIES AND FINGERPRINT ANALYSIS

Abstract

Using a set of monoclonal antibodies that recognize different antigenic determinants on CEA, we analyzed CEA and cross-reacting antigens in the PCA extracts of mammary, lung, and colonic tumors. We could show differences between colonic and lung tumor CEA and identify a molecule in a breast tumor PCA extract cross-reacting with a colonic tumor CEA that has the same molecular weight but is not identical with it. By fingerprint analysis of the CEA digested with thermolysin, we could demonstrate differences between the two lung tumor CEA bands and the colonic tumor CEA. The results could be supported by sequential digest with V8-protease. The MAb so far available cannot distinguish between colonic and lung tumor CEA and the two lung tumor CEA bands. No differences were found in the fingerprints of colonic tumor CEA after immunoprecipitation with the different monoclonal antibodies.