HLA-DR expression in bile duct damage in hepatitis C.

Several investigations have demonstrated aberrant expression of HLA-DR on damaged bile duct epithelium of patients with primary biliary cirrhosis, liver allograft rejection, graft versus host disease, and AIDS. Since bile duct damage is a prominent feature of chronic hepatitis C, it may also be associated with HLA-DR induction. Therefore, we examined the expression of HLA-DR antigen in formalin-fixed, paraffin-embedded liver biopsy sections of 30 patients with chronic hepatitis C by the avidin-biotin peroxidase complex method using a monoclonal antibody to HLA-DR. HLA-DR was not detected on bile duct epithelium in any of the cases, although bile duct damage of varying degree was observed in 90% of the cases. HLA-DR was expressed by Kupffer cells; inflammatory infiltrates in portal tracts, and in areas of piecemeal necrosis and lobular necrosis; dendritic cells in portal and periportal areas; and occasionally hepatocytes. These observations suggest that the mechanism of bile duct injury in chronic hepatitis C may be different from that of other conditions such as primary biliary cirrhosis, liver allograft rejection, and graft versus host disease.