Immunochemical characterization and cellular localization of pepsinogens in cat and dog

The antigenic relationships and cellular localization of cat and dog pepsinogens were investigated by electrophoretic analysis, immunodiffusion, immunoelectrophoresis, immunoabsorption, and by immunofluorescence, respectively. Rabbit antiserum to human and hog group I (Pg I) and group II pepsinogens (Pg II) had been previously prepared. Electrophoretic analysis revealed at least eight distinct proteases in extracts of gastric and proximal duodenal mucosa, resistant to alkalinization but destroyed by sequential accidification and neutralization. Rabbit antiserum to Pg I (anti-Pg I) and Pg II (anti-Pg II) produced a single precipitin arc against each extract forming a line of nonidentity. Immunoelectrophoresis of extracts produced a single precipitin arc against anti-Pg I or anti-Pg II. The specificity of the antibodies for the group I or group II pepsinogens was confirmed by immunoabsorption. By immunofluorescnece, both Pg I and Pg II were present in mucous neck and chief cells in fundic mucosa, in the pyloric gland cells in antral mucosa, and Brunner's glands in the proximal duodenum. The results indicate that canine and feline pepsinogens are electrophoretically heterogenous, that canine and feline Pg I share antigenic determinants with each other but not with Pg II, that a similar positive relationship exists for Pg II, and that both Pg I and Pg II are localized to the peptic cell mass, consisting of four types of cells.