Monitoring the natural course and response to therapy of chronic hepatitis B with an automated semi-quantitative assay for IgM anti-HBc

The clinical significance of a semi-quantitative 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 immuno-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 (