A STUDY OF IgG ANTIBODY-DEPENDENT CELL-MEDIATED CYTOTOXICITY IN PATIENTS WITH CHRONIC ACTIVE HEPATITIS

Abstract

Antibody-dependent cell-mediated cytotoxicity was studied in patients with chronic active hepatitis (CAH) and healthy controls (N) using a nonimmune normal non E-rosette forming cells (non E-RFC), tested sera and cultured rat liver cells (Coon cells) with a ratio of target cell to non E-RFC of 1:300. Non E-RFC alone showed a mild cytotoxicity to Coon cells in the absence of human sera (21.5±1.5%) and in the N-sera treatment of Coon cells (26.0±5.1%). After preincubation of Coon cells with CAH sera, % cytotoxicity of normal non E-RFC was increased to 49.4±8.7%. This augmentation of cytotoxicity by CHA sera was blocked by aggregated IgG, antihuman-IgG and -IgG/Fc. CAH sera, absorbed with Coon cells or rat hepatocyte-surface membranes, did not show any augmentation of cytotoxicity to Coon cells. In the absence of normal non E-RFC the control and test sera alone did not induce cytotoxicity to Coon cells.
In 7 of 10 sera from patients with CAH, membrane-fixed IgG on Coon cells was detected and showed a fine granular pattern. There was no difference of staining pattern between sera with and without HBsAg. Neither IgA nor IgM membrane-bound immunoglobulin was detected in CAH sera.
It would appear that the IgG-antibody-dependent cell-mediated cytotoxicity may play a role in pathogenesis of CAH.