[Immunoelectron microscopic localization of CEA in gastrointestinal malignancies].

Immunoperoxidase techniques were used to localize carcinoembryonic antigens (CEA) and secretory component (SC) in normal and abnormal human colonic, gastric and biliary tract mucosae. CEA was found on the microvillous surface of normal colonic cells, but not in biliary tract epithelial cells. However, little or no CEA and SC were found on normal gastric epithelial cells. On intestinal metaplastic cells, both antigens were present in a pattern similar to that of the normal colonic epithelium. Gastric and colonic adenoma cells showing severe dysplasia occasionally failed to maintain polar expression of both glycoproteins on the cell surface. In adenocarcinoma, this polar distribution was absent, and both glycoproteins were found all around the neoplastic cells as previously reported in colonic and gastric neoplasia. These observations suggest that deviations from normal differentiation and maturation, such intestinal metaplasia and adenoma of the gastrointestinal and biliary tract mucosa, are recognizable by alterations in the cell-surface distribution of CEA and SC, and neoplastic transformation of the epithelial cells may be accompanied by a loss of the normal polar distribution of surface membrane components.