Abstract
Carcinoembryonic antigen (CEA) and secretory component (SC) were localized by peroxidase-labeled antibody immunocytochemistry in normal and abnormal human gastric mucosa. In normal epithelium, both glycoproteins were absent or only faintly present, but in intestinal metaplasia and carcinoma both were prominently present. CEA and SC on the surfaces of metaplastic epithelial cells were polarized. That is, CEA was expressed only on the microvillous surface and SC was expressed only on the basolateral surface. In gastric cancer, CEA and SC were distributed over the entire surface of the neoplastic cells. Thus, deviations from the normal differentiation and maturation of gastric epithelial cells were accompanied by abnormalities in surface expression of CEA and SC. These observations, together with compatible observations previously made in colonic neoplasia (DJ Ahnen, PK Nakane, and WR Brown, Cancer 49:2077, 1982), suggest that loss of polarity of surface membrane components is a characteristic of neoplastic epithelial cells.