Epitopes of carcinoembryonic antigen (CEA) defined by monoclonal antibodies.
Of 15 anti-CEA monoclonal antibodies, the first 8 were reactive only with CEA, while the remaining 7 antibodies reacted with epitopes commonly expressed on CEA and the normal cross-reacting antigen, NCA. Separate and distinct, conformation-dependent (i.e. susceptible to reduction and alkylation), CEA-associated epitopes were identified using antibodies 1, 2 and 3. Antibodies 4 to 7 defined a series of conformation-independent epitopes which were topographically closely related on the CEA molecule. Antibody number 8 reacted with a separate determinant found on CEA but not NCA, and this also was resistant to reduction and alkylation. Antibody number 9 defined an epitope which was commonly expressed on CEA and NCA. This epitope was conformation-dependent and was the most sensitive to NaIO4. The remaining antibodies, 10 to 15, which also reacted with CEA and NCA, defined an immunodominant region of these molecules since the 6 epitopes were clearly closely related, but not necessarily identical. The findings presented establish a rational basis for the selection of combinations of anti-CEA antibodies for diagnostic and therapeutic purposes.
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000941:Antigens / Q000276:immunology; D000951:Antigens, Neoplasm; D001667:Binding, Competitive; D002272:Carcinoembryonic Antigen / Q000276:immunology*; D015815:Cell Adhesion Molecules; D000939:Epitopes / Q000032:analysis* / Q000276:immunology; D006023:Glycoproteins / Q000276:immunology; D007074:Immunoglobulin G / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D011487:Protein Conformation
D000911:Antibodies, Monoclonal; D000941:Antigens; D000951:Antigens, Neoplasm; D002272:Carcinoembryonic Antigen; D015815:Cell Adhesion Molecules; D000939:Epitopes; D006023:Glycoproteins; D007074:Immunoglobulin G