Clinical significance of quantitative anti-HBc IgM assay in acute and chronic HBV infection.

The applicability and clinical usefulness of anti-HBc IgM quantification in acute and chronic hepatitis type B by a single run of undiluted sera is largely unknown. Serum anti-HBc IgM concentrations were measured in 153 patients with various forms of acute and chronic HBV infection by a new commercially available qualitative ELISA/2-step capture assay applying streptavidin technology. The absorbance values were expressed in anti-HBc IgM U/ml using a calibration curve produced by a series of anti-HBc IgM standards. The results were compared with those obtained with another second generation qualitative anti-HBc IgM method also in undiluted sera applying the Microparticle Enzyme Immune Assay (MEIA). In acute hepatitis B, anti-HBc IgM was always > 600 U/ml (median: > 800 U/ml) declining to median values of 135 and 85 U/ml at months 3 and 6, respectively. Values above 600 U/ml were seen in 4 out of 20 (20%) HBsAg carriers with episodes of severe HBV-induced liver damage resembling acute hepatitis B (group 2) and in 2 out of 35 (5.6%) patients with HBV induced chronic active hepatitis (group 3). Values above 100 U/ml, representing the cutoff levels for the diagnosis of acute hepatitis B in the qualitative assays, were detected in 55% (11/20) and 45.7% (16/35) of the above patients of groups 2 and 3, respectively. Anti-HBc IgM was negative or under 20 U/ml in 96.7% (29/30) of HBsAg carriers with acute or chronic liver damage unrelated to HBV (HDV, HCV or drug-induced) and in 91% (41/45) of HBsAg carriers with persistently normal ALT levels.(ABSTRACT TRUNCATED AT 250 WORDS)