Autoimmune reaction to a liver specific membrane antigen during acute viral hepatitis.

Lymphocyte cytotoxicity for isolated hepatocytes has been demonstrated in 93% of cases of acute viral hepatitis tested within two weeks of the onset of symptoms. The frequency of cytotoxicity during this time was similar for HBsAg positive and negative cases. However, after this time it was significantly higher in HBsAg positive than negative cases, 90% and 25% respectively (P less than 0-01). Cytotoxicity was found in B-cell, but not T-cell, enriched fractions of lymphocytes, compatible with an antibody-dependent K-cell mediated reaction. In two cases the assay remained positive on retesting six months later, and follow-up liver biopsies showed the features of chronic aggressive hepatitis. These findings suggest that, in addition to the known immunological reactions against viral antigens that occur during the acute phase of viral hepatitis, an autoimmune reaction directed against a liver specific protein is also initiated; and if this reaction persists then chronic hepatitis may develop.