title: Immunochemical identification of an alpha 1-acid glycoprotein-antigenic determinant on carcinoembryonic antigen (CEA) and non-specific cross-reacting antigen (NCA).
abstract: An immunochemical characterization of carcinoembryonic antigen (CEA) and NCA (non-specific cross-reacting antigen) was performed. Positive reactions of CEA and NCA (Mr 60 000) with some antibodies to alpha 1-acid glycoprotein (AG) were observed. Thus, both antigens may contain immune determinants in common with alpha 1-acid glycoprotein. CEA showed positive reactivity with anti-NCA. NCA showed positive reactivity with either polyclonal or monoclonal antibodies to CEA, but negative reactivity with auto-antibodies to CEA. 125I-Tetracosapeptide (synthetic peptide-24 corresponding to the amino terminal sequence of CEA) failed to react with any antisera against CEA, NCA and AG. 125I-AG also showed no immuno-reaction with any antibody against CEA, NCA and tetracosapeptide. These results suggest that some monoclonal antibodies to CEA are directed against a common antigenic determinant of both CEA and NCA in addition to AG and tetracosapeptide, and that the auto-antibody to CEA is directed against a unique immune determinant which is not common to NCA. Thus, CEA appears to contain a unique determinant not found in NCA. Similarities in the composition of both amino acids and carbohydrates of CEA and NCA suggest that CEA is 'big-big' AG and NCA is 'big' AG.
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology; D000941:Antigens / Q000276:immunology; D000951:Antigens, Neoplasm; D001323:Autoantibodies / Q000276:immunology; D002272:Carcinoembryonic Antigen / Q000276:immunology*; D015815:Cell Adhesion Molecules; D002850:Chromatography, Gel; D003366:Cosyntropin / Q000276:immunology; D000939:Epitopes / Q000276:immunology*; D006023:Glycoproteins / Q000276:immunology*; D006801:Humans; D007163:Immunosorbent Techniques; D009369:Neoplasms / Q000276:immunology; D009961:Orosomucoid / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D000941:Antigens; D000951:Antigens, Neoplasm; D001323:Autoantibodies; D002272:Carcinoembryonic Antigen; D015815:Cell Adhesion Molecules; D000939:Epitopes; D006023:Glycoproteins; D009961:Orosomucoid; D003366:Cosyntropin