Evaluation of hepatic proliferative activity in chronic liver diseases and hepatocellular carcinomas by proliferating cell nuclear antigen (PCNA) immunohistochemical staining of methanol-fixed tissues.

The proliferative activity of chronic liver diseases and hepatocellular carcinomas (HCCs) was studied by PCNA immunohistochemistry. Human liver tissues were obtained by surgical operation or needle biopsy, and PCNA was detected by immunohistochemistry. PCNA-labelling indices (PCNA-LIs) of methanol-fixed tissues corresponded with the incidence of S-phase cells previously reported, whereas paraformaldehyde-fixed tissues showed extremely high PCNA-LIs in all specimens. Therefore, methanol-fixed tissues were used for evaluation. The PCNA-LIs of the methanol-fixed tissues were: normal liver 0.78 +/- 0.38%, chronic persistent hepatitis 1.06 +/- 0.86%, chronic aggressive hepatitis 2A 1.01 +/- 0.50%, chronic aggressive hepatitis 2B 4.20 +/- 1.79%, inactive cirrhosis 0.81 +/- 0.49%, active cirrhosis 1.96 +/- 0.93%, HCC of Edmondson's type I 4.83 +/- 1.98%, type II 6.65 +/- 1.69%, and type III 38.7 +/- 30.6%. PCNA-positive cells showed little specific distribution; in periportal areas in chronic hepatitis, at the margins of pseudolobules in cirrhosis, and throughout the tumor in HCC. These findings indicated that proliferative activity increased during the progression of chronic hepatitis, but that it decreased at the stage of cirrhosis. In chronic liver diseases, the PCNA-LIs reflected hepatitis activity. HCC showed higher proliferative activity than liver cirrhosis, and the histological grade was correlated with the PCNA-LI.