Serum interleukin-6 and interferon-gamma levels in patients with hepatitis B-associated chronic liver disease

Hepatitis B virus (HBV) infection can elicit a variety of clinical sequelae ranging from acute self-limited hepatitis to hepatocellular carcinoma, which are not attributable to a direct cytopathic effect of the virus but rather to the individual host's immune response. Cytokines, low-molecular-weight proteins with a broad range of activity, have been shown to be involved in the regulation of hepatocyte functions, as well as in the pathogenesis leading to liver damage. In the present study, we investigated the correlation between serum interleukin 6 (IL-6) and interferon gamma (IFN-gamma) in altogether 75 patients chronically infected with HBV. They comprised 15 asymptomatic carriers, 15 chronic persistent hepatitis (CPH) and 15 chronic active hepatitis (CAH) patients, 15 cases of cirrhosis and 15 patients with hepatocellular carcinoma (HCC) previously diagnosed by serology and histology, respectively. IL-6 and IFN-gamma levels in their sera were determined using a commercially available kit. Our results showed various concentrations of serum IL-6 detectable in 6.7% of asymptomatic carriers, 13.3% of patients with CPH, 20% of patients with CAH, 33.3% in cirrhotic patients and 66.7% in HCC. In contrast, serum IFN-gamma was only found in 13.3% of asymptomatic carriers and CAH, but could not be detected in the other groups. Our data demonstrated a positive correlation between serum IL-6 and clinical severity of chronic HBV infection, whereas the IFN-gamma levels appeared not to be correlated. From this we conclude that among chronic hepatitis patients IFN-gamma is mostly not expressed at a level detectable by serology, whereas according to other authors it is involved in the immediate immune response triggered by acute hepatitis. IL-6 on the other hand, might rather be responsible for liver inflammation and regeneration in chronic liver disease.