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Iron overload in the liver may occur in clinical conditions such as hemochromatosis and nonalcoholic steatohepatitis, and may lead to the deterioration of the normal liver architecture by mechanisms not well understood. Although a relationship between the expression of ICAM-1, and classical major histocompatibility complex (MHC) class I molecules, and iron overload has been reported, no relationship has been identified between iron overload and the expression of unconventional MHC class I molecules. Herein, we report that parameters of iron metabolism were regulated in a coordinated-fashion in a human hepatoma cell line (HepG2 cells) after iron loading, leading to increased cellular oxidative stress and growth retardation. Iron loading of HepG2 cells resulted in increased expression of Nor3.2-reactive CD1d molecules at the plasma membrane. Expression of classical MHC class I and II molecules, ICAM-1 and the epithelial CD8 ligand, gp180 was not significantly affected by iron. Considering that intracellular lipids regulate expression of CD1d at the cell surface, we examined parameters of lipid metabolism in iron-loaded HepG2 cells. Interestingly, increased expression of CD1d molecules by iron-loaded HepG2 cells was associated with increased phosphatidylserine expression in the outer leaflet of the plasma membrane and the presence of many intracellular lipid droplets. These data describe a new relationship between iron loading, lipid accumulation and altered expression of CD1d, an unconventional MHC class I molecule reported to monitor intracellular and plasma membrane lipid metabolism, in the human hepatoma cell line HepG2., This work was funded by the Inova Foundation for Medical Research/The American Portuguese Biomedical Research Fund (APBRF, USA). The authors would like to thank L. Mayer and K. Uchida for providing antibodies, A. do Vale, F. Pisarra and M.T. Silva for help and comments on TEM, and M. Santos and R. Hultcrantz for critical reading of the manuscript. We also thank M. de Sousa for mentoring this work. M.C. and C.F.P. were supported by a fellowship from Inova/APBRF. E.M.C. was partially supported by EU grant (QLG1-CT-1999–00665).

BACKGROUND: Although most Caucasian patients with hereditary haemochromatosis (HH) show the same mutation in the HFE gene, the phenotypic expression of the disease varies greatly. We have previously shown that patients with HH who have high iron stores have low numbers of circulating CD8+ T lymphocytes. PATIENTS AND METHODS: Liver and peripheral blood were studied in 37 C282Y homozygous HH patients; nine normal livers and 11 livers from patients with cirrhosis due to hepatitis C virus or alcoholic liver disease were also investigated. Eleven jejunal biopsies from HH patients and 17 normal biopsies were studied. The numbers of CD8+ cells were determined in peripheral blood by fluorescence-activated cell sorting analysis, and in the liver or small intestine by immunohistochemistry. RESULTS: In HH patients the number of CD8+ T lymphocytes in peripheral blood correlated significantly with the number of CD8+ cells in the liver lobuli but not with that in the small intestine. Body iron stores correlated negatively with the number of CD8+ T lymphocytes in peripheral blood and in the liver, but not with the number in the small intestine. HH patients with cirrhosis had the lowest CD8+ cell count in liver sections, in contrast with other forms of cirrhosis. CONCLUSION: The results indicate that HH patients with the HFE C282Y mutation and low numbers of CD8+ cells in the liver lobuli have higher iron stores and are more prone to develop liver cirrhosis., This study was supported by the Swedish Medical Research Council (n. 9127), the Bengt Ihres Foundation, Ruth and Richard Julins Foundation and the Karolinska Institute. Elsa Cardoso is a recipient of a PRAXIS XXI Grant BD/5095/95.

To determine the frequency of mutations (C282Y and H63D) in a newly identified gene HFE in patients with hereditary haemochromatosis (HH) in Sweden. DESIGN: Molecular genetic analyses of the HFE gene (polymerase chain reaction (PCR) followed by enzyme restriction) were performed in genomic DNA from unrelated patients with a clinical diagnosis of HH and in healthy subjects. SETTINGS: Patients with HH treated with phlebotomies at Karolinska Hospital and Huddinge Hospital were analyzed. SUBJECTS: Eighty-seven unrelated patients with HH and 117 healthy controls. RESULTS: It was found that the HFE C282Y mutation occurs in 94.2% of chromosomes from patients with HH. Eighty patients (92.0%) were homozygous for the C282Y mutation and one was heterozygous. Three patients were heterozygous for both C282Y and H63D mutations. One patient was homozygous and one was heterozygous for the H63D mutation. One patient carried normal alleles. In healthy controls, the C282Y mutation occurred in nine subjects (7.7%), all of which were heterozygous. The H63D mutation was found in 28 control subjects, one of which was homozygous. CONCLUSIONS: We found that the majority of patients with HH have the C282Y mutation in the HFE gene. The frequency of the H63D mutation was higher in controls than in patients with HH, although in chromosomes at risk the frequency of the H63D mutation was higher in patients., This study was supported by the Swedish Medical Research Council (n. 9127), the Swedish Society of Medicine, Ruth and Richard Julins Foundation and the Karolinska Institute. Miss Elsa Cardoso is a recipient of a PRAXIS XXI Grant BD/5095/95.