Characterization of effector cells in lymphocytotoxicity to autologous hepatocytes in HBsAg-positive and autoimmune chronic active hepatitis (CAH)

Abstract

— Peripheral blood lymphocyte subsets involved in cytotoxicity to autologous hepatocytes have been characterized by isolation on antibody‐coated Petri dishes in autoimmune and HBsAg‐positive chronic active hepatitis (CAH). In autoimmune CAH and in HBsAg‐positive CAH without HBcAg in liver tissue, cytotoxicity is sustained by non‐T lymphocytes and is confined to M1‐positive cells bearing Fc receptors: M1 cytotoxicity inhibition by adding aggregated IgG suggests that these cells are responsible for an antibody‐dependent cell‐mediated mechanism (ADCC). Moreover, when T‐enriched fractions were separated in T4, T8 and 5/9 positive subsets, only the first one showed a significant cytotoxicity: T4 positive cells might act as cytotoxic T cells or might be involved in delayed type hypersensitivity (DTH) reactions. Cytotoxic T lymphocytes in HBsAg‐positive CAH with HBcAg in liver tissue are confined in T8 positive subset, while helper/inducer T cells (T4 positive or 5/9 positive) seem to play an important role only in the induction of cell‐mediated injury against hepatocytes. The inhibition of T cell‐cytotoxicity by preincubating liver cells with monoclonal antibody (Mab) anti‐HLA AB and not with Mab anti‐HLA DR or aggregated IgG supports the involvement of the class I major histocompatibility complex (MHC) expressed on the hepatocyte surface.