Immunohistochemical identification of the cholecystokinin cell in the intestinal mucosa.

In indirect immunofluorescence tests, antibodies against pure porcine cholecystokinin (CCK) have detected specific CCK cells in the duodenal and jejunal mucosa of the dog and man. The CCK cells were scattered in the epithelium of the crypts, although some were in the villi. No CCK cells were found in the stomach, pancreas, terminal ileum, or colon. Some pyloric G cells also showed some reactivity with CCK antiserum, but absorption of CCK antiserum with gastrin C terminal pentapeptide prevented the staining of pyloric cells and provided specific staining of intestinal CCK cells. Anti-human gastrin I serum stained some intestinal cells too. Most of such cells did not react when gastrin antiserum was absorbed with pure CCK (a treatment that did not prevent the staining of pyloric gastrin cells); they were interpreted as cross-reacting CCK cells rather than as intestinal gastrin cells.