High inflammatory activity is associated with an increased amount of IFN-gamma transcripts in peripheral blood cells of patients with chronic hepatitis C virus infection

The mechanisms underlying the chronic hepatic inflammatory process in hepatitis C virus (HCV) infection are not well understood. Some models of experimentally induced hepatitis point to a role of interferon-gamma (IFN-gamma) secreted by liver-infiltrating peripheral blood lymphocytes (PBMC) in mediating hepatocellular injury. In the present study, IFN-gamma gene expression was analysed in PBMC and in liver biopsy specimens from patients with chronic HCV infection using a quantitative reverse transcriptase polymerase chain reaction technique. IFN-gamma gene expression by PBMC from HCV-infected patients exhibiting elevated serum transaminase activities was found to be increased up to ninefold when compared with (1) healthy individuals, (2) HCV-infected patients exhibiting normal or only slightly elevated serum enzyme activities, or (3) patients with drug-induced elevated serum transaminase activity. A histo-pathological evaluation of liver biopsy sections revealed further that high IFN-gamma gene expression by PBMC was associated with a more pronounced degree of inflammatory activity. In individual patients, the expression of IFN-gamma by PBMC was shown to parallel closely serum transaminase activities during IFN-alpha(2a) therapy. Moreover, liver biopsy material from patients chronically infected with HCV contained higher amounts of IFN-gamma transcripts than liver tissue from patients with liver disorders unrelated to HCV infection or without any liver disease. These data thus demonstrate a close association between the amount of IFN-gamma transcripts in PBMC and in liver tissue and the inflammatory activity in chronic HCV infection in man.