Immunohistochemical detection of Fas and apoptosis in type-1 autoimmune hepatitis

Although Fas expression has been reported in liver with chronic viral hepatitis and primary biliary cirrhosis, little is known about Fas expression and apoptosis in type-1 autoimmune hepatitis. The aim of this study was to investigate whether the expression of Fas and apoptosis are found in liver with autoimmune hepatitis. The relationship between Fas expression and clinicopathological findings including the occurrence of apoptosis was also investigated.

Fas expression and apoptosis were immunohistochemically examined in liver tissues from 20 patients with autoimmune hepatitis and five control subjects using specific antibodies against Fas and single-stranded DNA. The grade of expression of Fas and apoptosis was evaluated and compared with histological findings and the results of liver function tests in each patient.

Fas expression in hepatocytes was detected in all patients with autoimmune hepatitis, while Fas expression was not detected in control livers. The Fas-positive hepatocytes were particularly abundant in those areas facing piecemeal and confluent necrosis. In 30% of autoimmune hepatitis cases, bile-duct cells were faintly stained for Fas. A few hepatocytes positive for single-stranded DNA were found in the areas facing piecemeal necrosis and confluent necrosis. In 95% cases, many bile-duct cells were positive for single-stranded DNA. No relationship between the expression of Fas and single-stranded DNA was found in hepatocytes or bile-duct cells. However, the degree of Fas expression in hepatocytes significantly correlated with serum transaminase concentrations and was increased in parallel with the grade of activity but not with the stage of fibrosis.

We have demonstrated that Fas expression is detected in hepatocytes of the liver with autoimmune hepatitis and that the level of Fas expression reflects the severity of inflammation in autoimmune hepatitis.