Colon carcinoma-associated glycoproteins recognized by monoclonal antibodies CO-029 and GA22-2

Two murine monoclonal antibodies (MAb) CO-029 and GA22-2 are described which reacted specifically with the human gastrointestinal tumor cell lines LS180 and SW1222, respectively. CO-029 specific antigen was found by immunoprecipitation and Western blotting to be a highly expressed protein consisting of a single polypeptide chain of 32kDa. The gastric tumor associated antigen GA22-2 was a 185kDa polypeptide which did not comigrate with the 180 kDa carcinoembryonic antigen (CEA), neither was it immunologically crossreactive with the latter. Both CO-029 and GA22-2 antigens were shown to be glycosylated by their retention on Sepharose-lectin columns. CO-029 was highly bound by wheat germ agglutinin indicating the accessibility of N-acetylglucosamine or N-acetyl-neuraminic acid residues. GA22-2 showed higher specificity to soybean agglutinin inferring the preferential accessibility of galactose or N-acetylgalactosamine-like residues on its saccharide moiety.