CLINICAL-SIGNIFICANCE OF QUANTITATIVE ANTI-HBC IGM ASSAY IN ACUTE ANDCHRONIC HBV INFECTION

The applicability and clinical usefulness of anti-HBc IgM quantificati on in acute and chronic hepatitis type B by a single run of undiluted sera is largely unknown. Serum anti-HBc IgM concentrations were measur ed in 153 patients with various forms of acute and chronic HBV infecti on by a new commercially available qualitative ELISA/2-step capture as say applying streptavidin technology The absorbance values were expres sed in anti-HBc IgM U/ml using a calibration curve produced by a serie s of anti-HBc IgM standards. The results were compared with those obta ined with another second generation qualitative anti-HBc IgM method al so in undiluted sera applying the Microparticle Enzyme Immune Assay (M EIA). 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 %) pat ients with HBV Induced chronic active hepatitis (group 3). Values abov e 100 U/ml, representing the cutoff levels for the diagnosis of acute hepatitis B in the qualitative assays, were detected in 55 % (11/20) a nd 45.7 % (16/35) of the above patients of groups 2 and 3, respectivel y. Anti-HBc IgM was negative or under 20 U/ml in 96.7 % (29/30) of HBs Ag carriers with acute or chronic liver damage unrelated to HBV (HDV, I-ICV or drug-induced) and in 91 % (41/45) of HBsAg carriers with pers istently normal ALT levels. Values above 20 U/ml were also helpful dia gnostically, being observed in 90 % and 74.3 % of patients in groups 2 and 3, respectively. The MEIA assay gave similar results, but in gene ral, anti-HBc IgM levels were lower compared with the ELISA/2-step tec hnique. In conclusion, second generation qualitative assays of anti-HB c can be adapted and standardized to measure antibody concentrations i n U/ml by a single run of undiluted sera. They are helpful in the diag nosis not only of acute hepatitis B, but also of chronic hepatitis in HBsAg carriers induced either by the wild type and the precore mutated HBV and its differentiation from chronic liver damage of other aetiol ogy or from the healthy HBsAg carrier state. Because of its high diagn ostic value, simplicity and overall superiority, serum anti-HBc IgM qu antification must replace the qualitative anti-HBc IgM assays widely u sed in clinical practice.