MONITORING THE NATURAL COURSE AND RESPONSE TO THERAPY OF CHRONIC HEPATITIS-B WITH AN AUTOMATED SEMIQUANTITATIVE ASSAY FOR IGM ANTI-HBC

The clinical significance of a semi-quantitiative microparticle enzyme immunoassay (IMx Core-M, Abbott) was evaluated for detection of IgM-class antibodies against the hepatitis B core antigen (IgM anti-HBc) in 136 hepatitis B surface antigen (HBsAg) positive individuals (96 chronic HBV carriers, 20 patients with chronic HBV-HDV infections and 20 patients with acute hepatitis B) and 50 HBV-negative controls. Baseline and follow-up sera (4-11 samples) were analysed from 79 carriers with chronic hepatitis B, 44 of whom were treated with interferon. IMx indexes above 3.000 were found in 95% of the acute hepatitis B patients and above 0.300 in 91.5% of patients with ongoing chronic hepatitis B. IMx indexes between 0.200 and 0.300 were observed in (a) patients with recent HBeAg to anti-HBe seronconversion (6-12 months) and normal serum ALT levels, (b) patients immune-tolerant to HBV infection and without liver disease despite high levels of viremia, and (c) patients with anti-HBe-positive chronic hepatitis B during 7-13-month intervals of asymptomatic carriage between episodes of disease reactivation. IMx indexes below 0.200 were detected in all HBV-negative individuals and healthy HBV carriers, in 14 (70%) of 20 chronic hepatitis D patients and in all but 1 of 22 interferon-treated patients with histological remission of liver disease, 5-12 months after clearance of viremia and normalization of serum ALT levels. In contrast, IMx indexes remained above 0.200 in all patients with hepatitis B reactivation. These results suggest that the semi-quantitative analysis of serum IgM anti-HBc is a useful non-invasive tool for the diagnosis and monitoring of chronic hepatitis B. In patients with undetectable viremia and normal serum aminotransferases levels, an IgM anti-HBc index below 0.200(<10 PEI units) is associated with persistent remission of liver disease while values above 0.200 represent the hallmark of hepatitis B reactivation.