Ferritin and lysozyme distribution in normal and abnormal duodenal mucosae.

The distribution of ferritin and lysozyme in 19 normal and abnormal duodenal biopsies was studied by an immunoperoxidase technique. The abnormal biopsies included cases of chronic duodenitis with gastric metaplasia, gastric heterotopia, villous atrophy, and a case of hemochromatosis. Ferritin is demonstrated in duodenal absorptive cells, with the staining being most intense in the hemochromatosis case. It was absent in duodenal cells showing gastric metaplasia and in the surface epithelial cells of most biopsies with villous atrophy and gastric heterotopia. Lysozyme-positive mononuclear inflammatory cells were markedly increased in all abnormal biopsies. Not all lysozyme-positive cells were ferritin positive. The latter were especially abundant in areas with gastric metaplasia. It is suggested that this abundance may be related to passive diffusion of intestinal contents, particularly iron, through the metaplastic areas, and consequently there may be a relationship between the presence of duodenal gastric metaplasia and uncontrolled iron absorption.