Immunohistochemistry of HFE in the duodenum of C282Y homozygotes with antisera for recombinant HFE protein

Abstract

BACKGROUND AND OBJECTIVE: HFE is a class-I MHC related protein which carries the C282Y mutation in most patients with hereditary hemochromatosis, an iron overload disease. HFE protein is expected to have a relevant role in the regulation of duodenal iron absorption, and HFE protein was immunohistochemically identified in the crypt cells. The aim of the work was to analyze whether the C282Y mutation affects HFE accumulation in the duodenum. DESIGN AND METHODS: We developed antisera for the extracellular portion of recombinant human HFE protein expressed in E. coli. The antisera were specific for HFE protein and the C282Y mutant in immunoblotting, immunoprecipitation and immunocytochemistry experiments of transfected cells, and they did not cross react with HLA antigens in various analyses. The antisera gave positive results in the staining of paraffin-fixed sections of duodenal slices of subjects with hemochromatosis. RESULTS: The antisera stained evident supranuclear granules in all enterocytes of 7 C282Y homozygous subjects, and a dark area in the same region in 3 other C282Y homozygotes. Granular bodies were absent from the duodenal sections of 8 C282Y negative subjects, from 2 C282Y heterozygotes and 3 C282Y homozygotes, with or without hemochromatosis. INTERPRETATION AND CONCLUSIONS: The detection of HFE-protein in granular bodies in the enterocytes of the large majority (77%) of C282Y homozygotes and not in other subjects suggests that the mutation facilitates protein accumulation in the duodenum.