Semiquantitative assessment of IgM antibody to hepatitis B core antigen and prediction of the severity of chronic hepatitis B

Controversial results have been reported concerning the correlation between serum levels of IgM antibodies to hepatitis B core antigen (IgM HBcAb) and the histological activity of chronic hepatitis B. In this study, paired serum samples and liver biopsies were collected from 200 consecutive chronic hepatitis B patients (mean age 39.2 +/- 0.8 years; M:F 154:46; 41 hepatitis B e antigen (HBeAg) positive) and tested for IgM HBcAb using a semiquantitative highly sensitive assay (IMx CORE-M (R)). The severity of liver disease was assessed by the Ishak score, grading the necroinflammatory activity (by using the histology activity index, HAI) and staging the fibrosis. The index values of IgM HBcAb were significantly different among patients with mild (HAI less than or equal to 6), moderate (HAI 7-12) and severe (HAI greater than or equal to 13) necroinflammatory activity but the stage of fibrosis was unrelated to the IgM HBcAb. According to the index value of IgM HBcAb, we selected three groups of patients: Group A included 36 patients with an index value below 0.200; Group B, 99 patients with an index value between 0.200 and 0.500; and Group C, 65 patients with an index value over 0.500. The mean HAI grading in Group A was 5.3 +/- 0.4, in Group B it was 7.4 +/- 0.3 and in Group C it was 8.9 +/- 0.4 (f = 16.5, P < 0.0001). A mild HAI grading was observed in 77.8% of Group A, in 47.5% of Group B and in 23.1% of Group C patients; conversely, severe grading was detected in 0% of Group A, in 11.1% of Group B and in 18.5% of Group C patients (P < 0.0001). An index value of IgM HBcAb below 0.200 was 75% predictive of a mild necroinflammatory activity (29% sensitivity and 91.6% specificity) and ruled out a severe activity. Therefore, the quantitative assessment of IgM HBcAb appears to be a useful clinical tool in the prediction of the necroinflammatory activity of chronic hepatitis B. A serum index value of IgM HBcAb consistently below 0.200 could be considered a surrogate marker of remission of hepatitis B virus-induced liver disease.