Significance of IgM antibody to hepatitis B core antigen for the differential diagnosis of acute and chronic hepatitis B virus infection and for the evaluation of the inflammatory activity of type B chronic liver diseases.

IgM antibody to hepatitis B core antigen (anti-HBc) was assayed using a commercial kit in acute and chronic hepatitis B virus (HBV) infection and evaluated for its diagnostic and clinical significance. IgM anti-HBc was positive in all of 21 cases with type B acute hepatitis in the acute phase, and was also detected in 5 of 20 cases with type B chronic persistent hepatitis, in 4 of 20 patients with type B chronic active hepatitis and in one of 10 with type B liver cirrhosis. The absence of this marker was noted in all of 20 asymptomatic hepatitis B surface antigen (HBsAg) carriers and in 50 with HBsAg-negative patients with liver disease and in 200 healthy blood donors. The cut-off index of IgM anti-HBc was greater than 2.0 in all serum samples obtained in the acute phase of type B acute hepatitis, but was below 2.0 in type B chronic liver disease. A close relationship was found between the presence of IgM anti-HBc and the degree of inflammatory activity in patients with HBsAg-positive chronic liver disease. These data show that examination of IgM anti-HBc is useful in distingushing type B acute hepatitis from type B chronic liver disease, and also in evaluating the severity of disease in type B chronic liver disease.