Immunochemical studies of the endocrine cells of the gastrointestinal tract. I. The use and value of peroxidase-conjugated antibody techniques for the localization of gastrin-containing cells in the human pyloric antrum.

This paper describes and immunochemical localization of gastrin-containing endocrine cells in the human pyloric antrum using antibodies conjugated to horseradish peroxidase. With pre-fixed cryostat sections, a distinct clear-cut staining of gastrin-containing cells can be obtained either by direct or indirect single stain procedures, but may cells containing endogenous peroxidase activity also stain. In order to abolish staining due to endogenous peroxidase, sections were pretreated with a number of inhibitors prior to incubation in immune sera, but the inhibitors used appeared to interfere with the antigenicity of the gastrin molecule since subsequent immunochemical localization was impossible. The application of a double-staining technique, however, allowed us to distinguish easily between those cells which contained endogenous peroxidase and those on to which labelled antibody had been adsorbed. No labelled cells were found in post-fixed cryostat sections of fresh-frozen tissue. The technique is of value because preparations are permanent, a fluorescence microscope is not required, and the same technique can be adapted for use with the electron microscope.