Constituents and Antigens of Normal Human Gastric Mucosa as Characterized by Electrophoresis and Immunoelectrophoresis in Agar Gel

Abstract

Mucosal extracts of 20 normal human stomachs obtained at surgery were characterized by chemical methods after electrophoresis and immunoelectrophoresis in agar gel. Nine protein fractions were observed after electrophoresis, three of which migrated faster than serum albumin. Using absorbed rabbit antigastric mucosal antisera nine specific mucosal antigens were found and classified according to their electrophoretic and immunoelectrophoretic mobility. The SE and IE patterns of glycoproteins, carboxylic esterases, lactic dehydrogenases, acid phosphates, peroxydases, catalase have been described. Proteolytic activities with a pH optimum in the strongly acid range were detected in the anodic region corresponding to four pepsin-like enzymes, three of which have been shown to be antigenic. Esterase activity was found at five different electrophoretic sites but only one precipitin line in the cathodic region stained for the same activity. Two lines near the center well were characterized as glycoproteins. Contamination of mucosal extracts by blood and other nonmucosal constituents was evaluated in SE by successive extraction of the mucosa and by comparison with blood, normal human serum, gastric muscularis and mucus. Catalase and peroxydase activities proved to be due to blood contaminants. Several plasma proteins were identified in the different gastric extracts by immunoelectrophoresis. The organ specificity of the nine gastric mucosal antigens was established by absorption studies with blood, erythrocytes, plasma and other human organ extracts. Two of the nine antigens disappeared after absorption of the antiserum with human small intestine. No significant differences were observed in the electrophoretic and immunoelectrophoretic patterns of the individual stomachs. By combining electrophoretic, immunoelectrophoretic and chemical characterization methods a typical pattern of normal gastric mucosal constituents and antigens has been established to serve as a baseline for further investigation of alterations in malignant gastric mucosae.