Immunohistochemical survey of cobalamin-binding proteins

Eun Y. Lee, Bellur Seetharam, David H. Alpers, Katherine DeSchryver-Kecskemeti

Research output: Contribution to journalArticle

26 Scopus citations

Abstract

Dietary cobalamin is bound to intrinsic factor (IF) and nonintrinsic factor (R protein) in the gastrointestinal tract. Distribution of IF has previously been described only in the stomach (parietal, chief cells), duodenum (mucous cells), and pancreatic juice. Cells containing R protein have been reported to be more widespread, including mucin-secreting cells of the intestinal tract. To further clarify the cells producing these cobalamin binders in the various organs, we surveyed a number of tissues in four species, with monospecific antisera raised against rat IF and hog R protein, using indirect immunoperoxidase histochemistry. A positive staining pattern was confirmed after blocking with the appropriate protein purified to homogeneity. Strong IF staining was noted over chief cells in the rat stomach, with weaker but substantial staining in the parietal cells as well. Intrinsic factor was found only in parietal cells in all other species examined. R protein was found in parietal cells of all species tested, except in the hog, where mucous cells of the basal crypt stained. The area of the brush border and apical cytoplasm in small intestinal epithelial cells was also positive for both IF and R protein, probably reflecting uptake. Accessory digestive organs, such as salivary gland and pancreas were also positive for both IF and R protein in the secretory ducts. Accessory digestive organs contribute to the secretion of IF as well as R protein, but the physiologic importance of this IF secretion is not clear.

Original languageEnglish
Pages (from-to)1171-1180
Number of pages10
JournalGastroenterology
Volume97
Issue number5
DOIs
StatePublished - Nov 1989

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