The role of IgM anti-HBc in the etiologic diagnosis of HBsAg-positive acute and chronic hepatitis.
HBsAg, HBeAg, anti-HBc, anti-HBs, IgM anti-HAV, total and IgM anti-delta (RIA) and IgM anti-HBc (ELISA) have been determined on sera of 72 male patients with acute hepatitis (68 HBsAg positive and 4 anti-HBc-positive) at the onset of the disease and at 2, 4 and 6 months thereafter, and of 77 patients with HBsAg-positive chronic active hepatitis. The results indicate that testing for IgM anti-HBc in acute hepatitis is necessary to identify cases of hepatitis B even in the absence of positivity for HBsAg and/or HBeAg. HBsAg-positive cases, negative for IgM anti-HBc, were due to delta superinfection of chronic carriers of HBsAg. Recovery was always associated with negativity of IgM anti-HBc; IgM anti-HBc persistence was not found in all cases evolved to chronicity. In chronic hepatitis cases positivity for IgM anti-HBc was found only in 39% of the anti-delta-negative and only in 5.5% of the anti-delta-positive cases.