IgM levels and IgM-mediated immune responses in patients with acute hepatitis A, acute hepatitis B and chronic HB antigenaemia.
Immunoglobulin M (IgM) levels and their relationship to isohaemagglutinins, febrile agglutinins, sheep cell agglutinins, and rheumatoid factor were measured in patients with acute hepatitis A, acute hepatitis B, chronic hepatitis B antigenaemia, and normal control populations. Significant IgM elevations were observed in both types of acute hepatitis, but not in chronic hepatitis B antigenaemia. There was no correlation of the IgM level with either the prevalence or titre of any IgM-mediated immune response studied. These data suggest that the IgM elevations in both types of hepatitis may reflect virus-specific IgM synthesis.