Bile duct cell apoptosis is a rare event in primary biliary cirrhosis

Abstract Background . The frequency of apoptosis in bile duct cells of primary biliary cirrhosis is still unclear, spanning from rare to 50% in the various reports. Aim . To study bile duct cell apoptosis in stage I primary biliary cirrhosis lesions. Patients . Nine stage I-II biopsies with a total number of 26 bile ducts of different sizes, selected from a larger series on the basis of the expression on serial frozen sections of HLA-DR and Fas antigens. Methods . Apoptosis was evaluated by a DNA fragmentation assay on frozen sections, according to the manufacturer's protocol and by expression of apoptosis related cytokeratin neoepitopes. Bile duct cell proliferation was assessed by MIB1 [Ki-67] expression. Results . Apoptosis was frequently found in inflammatory cells of portal tracts and sinusoids. Apoptosis of hepatocytes was also systematically observed. Only 4 positive bile duct cells were found in 3 bile ducts from 3 biopsies. Quantitative evaluation was not attempted. Cholangiocyte proliferation was observed in the same ducts and occasionally in other biopsies. Conclusions . These data suggest that cholangiocyte death by apoptosis at the level of typical primary biliary cirrhosis lesions is a rare event, at least in early stages of the disease. The observed rate of proliferation was consistent with the rate of apoptosis.