Study of immunoglobulin M antibody against hepatitis B core antigen in patients with HBV infection

Immunoglobulin M antibody against hepatitis B core antigen (anti-HBcIgM) was measured by radioimmunoassay in order to study its efficacy in the diagnosis of HBV infection. Anti-HBcIgM were detected in 4 of 30 patients with HBsAg negative acute hepatitis and 5 of 15 patients with HBsAg negative fulminant hepatitis. These 9 patients were not accurately diagnosed as hepatitis type B until anti-HBcIgM was detected. In the sera obtained within 6 weeks from the onset, antiHBcIgM titers were higher than 4.0 by cut off index (C.I.) in patients with acute hepatitis type B in contrast to the lower titer (lower than 3.9 by C.I.) in those with chronic HBs antigenemia. In fulminant hepatitis type B, the peak of the titer was reached earlier and its titer remained higher than in acute hepatitis type B. However, this antibody were undetected in patients with simultaneous infection of HAV and HBV. We conclude that the detection of anti-HBcIgM is a useful method for the diagnosis of HBV infection.