Immunochemical differences among carcinoembryonic antigen in tumor tissues and related antigens in meconium and adult feces.
We have isolated carcinoembryonic antigen (CEA)-related antigens from meconium and compared them with those in adult feces. Two CEA-related antigens were detected in meconium [nonspecific cross-reacting antigen 2 (NCA-2) and meconium nonspecific cross-reacting antigen] while four CEA-related antigens were found in adult feces [normal fecal antigen 1, normal fecal antigen 2 (NFA-2), normal fecal cross-reacting antigen, and fecal nonspecific cross-reacting antigen, respectively]. By conventional anti-CEA antisera, NCA-2 in meconium, NFA-2 in adult feces, and CEA in tumor tissues were indistinguishable from each other, but they could be distinguished by specific antibody preparations against a determinant unique to CEA (CEA-distinctive determinant) or to NFA-2 (NFA-2-distinctive determinant). Neither the CEA-distinctive determinant nor the NFA-2-distinctive determinant was detected on the NCA-2 molecule. No antigenic determinants unique to NCA-2 have been detected with the anti-NCA-2 antisera which we have prepared thus far. The molecular weight of purified NCA-2 was estimated to be 150,000 to 170,000 as compared to 160,000 to 170,000 for NFA-2 and 170,000 to 180,000 for CEA. NCA-2 had amino acid and carbohydrate compositions similar to those of CEA and NFA-2. All NFA-2 preparations and about one-half of the CEA preparations were sensitive to Pronase E digestion, which released two antigen fragments from these molecules, but NCA-2-preparations were resistant to such digestion.
D000596:Amino Acids / Q000032:analysis; D000918:Antibody Specificity; D000951:Antigens, Neoplasm; D002241:Carbohydrates; D002272:Carcinoembryonic Antigen / Q000302:isolation & purification*; D015815:Cell Adhesion Molecules; D003429:Cross Reactions; D000939:Epitopes / Q000032:analysis / Q000276:immunology; D005243:Feces / Q000032:analysis*; D006023:Glycoproteins / Q000302:isolation & purification*; D006801:Humans; D005779:Immunodiffusion; D007122:Immunoelectrophoresis; D008470:Meconium / Q000276:immunology*; D008970:Molecular Weight; D009369:Neoplasms / Q000276:immunology; D011402:Pronase / Q000494:pharmacology*
D000596:Amino Acids; D000951:Antigens, Neoplasm; D002241:Carbohydrates; D002272:Carcinoembryonic Antigen; D015815:Cell Adhesion Molecules; D000939:Epitopes; D006023:Glycoproteins; D011402:Pronase