Distribution of Gastrin in Human Digestive Organs Demonstrated by Direct Immunofluorescence

1. Antiserum was prepared in the rabbit against synthetic human gastrin I conjugated with bovine serum albumin. The IgG fraction of this specific antiserum was labelled with FITC (fluoresceine isothiocyanate). With a direct immunofluorescence technique the distribution of gastrin in the human digestive tract and associated glands was investigated with special reference to extragastric gastrin. 2. Gastrin-containing cells were numerous in the antral mucosa of the human stomach especially in the prepyloric region (2-4cm proximal to the pylorus). In the body and cardia of the stomach no gastrin-containing cells were seen. 3. Some gastrin-containing cells were seen in the duodenum but fewer than in the antrum and they decreased distally. 4. No gastrin-containing cells were seen in the esophagus, jejunum, ileum and colon. 5. In the pancreas numerous autofluorescent granules were seen, but no specific gastrin-containing cells. Nor could these cells be found in the parotid and submandibular glands. 6. The release of gastrin after immersion in 0.5M glycine solution was investigated. A slight decrease of the specifically fluorescent substance could be seen. A complete release of the substance followed freezing in an isopentane bath in aqueous nitrogen.