Immunohistochemistry of the Hfe protein in patients with hereditary hemochromatosis, iron deficiency anemia, and normal controls.

ABSTRACT

In 1996 two mutations in Hfe, the gene affected in hereditary hemochromatosis, were identified as C282Y (c.845G. A) and H63D (c.187C. G). Immunohistochemical studies have localized the protein product of Hfe to the deep crypts of the duodenum, the maximum site of iron absorption. To date, there are no published data on the cellular location and regulation of Hfe in patients with hemochromatosis who are homozygous for C282Y. The aim of this study was to identify the cellular localization of Hfe in genotyped individuals and to study possible regulation of this protein by the mutations described in the Hfe gene locus and iron deficiency. Duodenal biopsy specimens and serum for iron, ferritin, and transferrin saturation were taken from controls (n = 10) and patients with hereditary hemochromatosis (n = 10) and iron deficiency anemia (n = 10). All participants were genotyped for C282Y and H63D mutations. Expression of Hfe in the duodenum was demonstrated by immunohistochemistry. Hfe was expressed in the deep crypts of the duodenum in all three groups in a perinuclear fashion. Hfe staining was weaker in the hemochromatosis and iron deficiency patients (mean transferrin saturation 69.6%, SD 23% and 15%, SD 11%, respectively) when compared to controls (mean transferrin saturation 33.1%, SD 15%). There was no difference in the intensity of Hfe staining within the hemochromatosis group who were iron overloaded when compared to their iron-depleted counterparts. In summary, Hfe is expressed strongly in the deep crypts of the small intestine of normal subjects. Homozygosity for C282Y and conditions of iron deficiency result in a downregulation of Hfe. Furthermore, Hfe is not regulated by therapeutic iron depletion in patients with hemochromatosis who are homozygous for the C282Y mutation.