Immunohistochemical observation of Fas in the human liver: light and electron microscopic observation by immuno-peroxidase method

The expression of Fas was examined in liver specimens from 18 patients with various liver diseases (8 type B chronic hepatitis, 7 type C chronic hepatitis, 2 autoimmune hepatitis and one fatty liver) and normal liver specimens obtained from 2 patients under surgical treatments for metastatic liver cancer, by light and electron microscopy using the indirect peroxidase-labelled antibody method. Fas was detected on the surface of hepatocytes in all cases. By immunoelectron microscopy, dense reaction products were observed on the plasma membrane facing both the Disse's and intercellular spaces, as well as in some membranes of the endoplasmic reticulum. In patients with severe or moderate chronic liver inflammation, strongly Fas-positive hepatocytes were distributed diffusely throughout the lobules. On the other hand, in patients with minimal hepatic inflammation, Fas expression was weak, and localized mainly in hepatocytes of the centrilobular area. These findings confirm the localization of Fas on the plasma membrane of hepatocytes, and suggest that Fas expression may increase with increasing degree of intrahepatic inflammation.