Serum levels of soluble Fas antigen in chronic hepatitis C patients

Background/Aims: In chronic hepatitis C, the expression of Fas antigen on hepatocytes is upregulated and Fas ligand expression is detected on liver-infiltrating mononuclear cells. Thus Fas antigen/Fas ligand-mediated apoptosis is thought to be involved in hepatic injury in chronic hepatitis C. The soluble form of Fas antigen has been detected in serum and shown to inhibit Fas-mediated apoptosis. The present study was done to evaluate the relationship of serum soluble Fas antigen levels with disease activity. Methods: Serum soluble Fas antigen levels were measured by enzyme-linked immunosorbent assay for 68 chronic hepatitis C patients and compared with those in normal volunteers, chronic hepatitis B patients and autoimmune hepatitis patients. These levels were compared with histological activity, ALT levels, HCV-RNA titer and Fas expression on hepatocytes. Results: Serum soluble Fas antigen levels in chronic hepatitis C patients (3.24+/-1.55 ng/ml) were significantly higher than those in normal volunteers (1.70+/-1.01 ng/ml) (p<0.01). They showed no difference from those in chronic hepatitis B or autoimmune hepatitis patients. Histologically, soluble Fas antigen levels showed correlation with the levels of liver inflammation (p<0.01). However, no relationship was observed between serum soluble Fas antigen and serum ALT levels or HCV-RNA titer. Serum soluble Fas antigen levels showed correlation with the levels of Fas antigen expression in liver tissue (p<0.05). Conclusions: These findings suggest that serum soluble Fas antigen may reflect the expression levels of Fas antigen on hepatocytes and the severity of liver inflammation in chronic hepatitis C,