In vitro studies on IgG-mediated lymphocyte cytotoxicity in chronic active liver disease

Abstract

Antibody-dependent cytotoxicity in chronic active liver disease (CALD) (10 subjects), mediated by allogeneic nonimmune lymphocytes (NL), was studied in vitro. NL in significant numbers adhered to the surface of target Chang monolayer cells, pretreated with the sera of CALD patients (immune adherence of NL) and were cytotoxic. This was blocked by anti-IgG and IgGFc. Test sera, absorbed with Chang cells or human adult liver tissues, failed to provoke target Chang cell lysis. Small amounts of granular-appearing IgG were demonstrated on the surface of Chang cells treated with the CALD sera from 8 of the 10 patients (membrane-fixed IgG). It is concluded that the antibody-dependent cellular cytotoxicity in this in vitro system is mediated by the IgG of CALD sera, most likely bound to target cell surface antigens, and that effector NL appear to lyse the target cells by direct contact through the Fc portion of the above membrane-fixed IgG. This immune cytotoxic process may play a role in the pathogenesis of CALD.