Studies on IgA antibody to hepatitis B core antigen in patients with acute and chronic hepatitis B virus infection

The IgA antibody to hepatitis B core antigen (IgA anti-HBc) was examined on 93 sera from 68 patients with hepatitis B virus (HBV) infection. The high titer of IgA anti-HBc was frequently present in the patients except healthy HBs antigen carrier and chronic inactive hepatitis, and the titer in the patients with HBe antigen carrier was significantly higher than in the antigen-free patients. The pattern of IgA anti-HBc changes was similar to that of IgM anti-HBc in the acute phase of HBV infection. In chronic infection, however, this phenomenon was not observed. In addition, the IgA anti-HBc of acute HBV infection was proved to be a polymeric IgA, while that of chronic infection was a monomeric IgA, From these results, the occurrence of IgA anti-HBc is assumed to reflect on the active liver disease, and the molecular form of IgA anti-HBc is a specific indicator for the differentiation of acute HBV infection from chronic HBV infection.