[Studies on immunological characteristic of CEA--CEA may be a biosynthetic precursor of alpha 1-acid glycoprotein--]

The purified CEA preparation by anti-alpha 1-acid glycoprotein (AG) chromatography shows specific binding with both auto-antibodies for CEA in cancerous patients and the monoclonal antibody for CEA. By this method CEA purification is possible. CEA preparation obtained from CEA producing cell line and CEA producing tumor grafted in nude mice contain AG antigenic determinants. Both tumors also contain free AG (Mr, 50,000). When tryptic hydrolysis of purified CEA preparation is performed, AG-like protein (Mr, 30,000) is released. The carbohydrate composition and amino acid content of both CEA and AG have a significant similarity. We postulate that CEA may be a biosynthetic precursor of AG based on differences in binding affinities between CEA with anti-CEA and with anti-AG.