HEPATOCELLULAR EXPRESSION OF LYMPHOCYTE FUNCTION ASSOCIATED ANTIGEN-3 IN CHRONIC HEPATITIS

T lymphocyte-mediated cytolytic immune reactions are considered a major cause of hepatocyte injury in chronic viral and autoimmune hepatitis. To further investigate local immune responses, we studied the expression of lymphocyte antigens and cell-cell interaction molecules known to be involved in effector-target cell interactions by light and electron microscopy in liver biopsy specimens from patients with chronic viral and autoimmune hepatitis. CD8+ lymphocytes were found to be the predominant population of cells in the inflammatory infiltrate in chronic hepatitis B and non-A, non-B hepatitis. In contrast, CD4+ cells constituted a comparably higher proportion of cells and were more numerous than CD8+ cells in chronic autoimmune hepatitis. In both viral and autoimmune hepatitis, a substantial portion of lymphocytes expressed activation antigens such as T11/3 (CD2R) and IL-2-R (CD25). Lymphocyte function-associated antigen-3 (CD58), which mediates lymphocyte adhesion and activation and is the natural ligand of the CD2/T11 lymphocyte surface receptor, could be demonstrated on endothelial cells and hepatocytes. Hepatocellular lymphocyte function-associated antigen-3 expression in chronic hepatitis showed membranous and cytoplasmic staining of hepatocytes and had a positive correlation with the degree of inflammatory activity. These results suggest that effector-target interactions between hepatocytes and lymphocytes mediated by the lymphocyte function-associated antigen-3/CD2 pathway play a role in chronic inflammatory liver disease. Possible functional consequences of this interaction include enhancement of antigen-specific immune reactions and antigen-independent mechanisms of T cell activation, which may contribute considerably to the degree of inflammatory activity and tissue damage in chronic hepatitis.