Monomeric (7S) immunoglobulin M antibodies to hepatitis delta virus in hepatitis type D

The pattern of the immunoglobulin M antibody to the hepatitis delta virus distinguishes acute from chronic hepatitis D. Expression of the immunoglobulin M antibody to the hepatitis delta virus is relatively weak and short-lived in self-limited hepatitis but strong and persistent in chronic forms. To study the nature of the immunoglobulin M antibody to the hepatitis delta virus in acute hepatitis D and in chronic hepatitis D, antibody-positive sera were submitted to rate zonal centrifugation to separate monomeric 7S from pentameric 19S immunoglobulin M antibodies. Sera were from 6 patients with acute self-limited hepatitis, 4 patients with chronic hepatitis D, and 6 patients with hepatitis D progressing to chronicity. The immunoglobulin M reactivity was measured by a specific immunoassay based on capture of mu-chains by anti-mu linked on a solid phase. Only 19S antibody was found in acute hepatitis D. In contrast, all patients with chronic hepatitis D circulated 7S antibody in addition to the 19S antibody. In patients with progressive hepatitis D, both the 7S and 19S antibody variants were present at the onset of the disease. The difference in the antibody response between acute hepatitis D and chronic hepatitis D is not only temporal and quantitative but also qualitative. The expression of 7S antibody seems to be an immunologic event specific for chronic hepatitis D.