Immunohistochemical studies on intrahepatic lymphocyte infiltrates in chronic type B hepatitis, with special emphasis on the activation status of the lymphocytes.

To study the immunopathogenesis of chronic type B hepatitis, we used a panel of monoclonal antibodies to characterize the intrahepatic mononuclear cell infiltrates in 39 patients with various forms of chronic hepatitis induced by hepatitis B virus (HBV) and, for comparison, in 10 with non-A, non-B (NANB)-induced chronic hepatitis. In portal areas, the OKT4:OKT8 ratio reversed because of the relative increase of OKT8+ cells. The mean intraportal T4:T8 ratio was significantly lower in HBV-associated chronic active hepatitis (CAH) than in chronic persistent hepatitis induced by HBV or NANB viruses. OKT8+ cells were predominant in the infiltrates of periportal areas (piecemeal necrosis) and lobules. As to the activation status of the infiltrates, T10 was found much more frequently on mononuclear infiltrates of piecemeal necrosis and peripheral portion of portal areas in CAH cases, regardless of viral etiology, and its existence was correlated with the severity of CAH. Natural killer cells, killer cells, and B-cells played little role in the pathogenesis of hepatocytolysis. We conclude that T-cell cytotoxicity is the main mechanism of hepatocytolysis, either in lobules or in periportal regions, and that T10 antigen defines a group of cells which may play an important role associated with the formation of piecemeal necrosis.