Antibody-dependent cell-mediated (K cell) cytotoxicity against isolated hepatocytes in chronic active hepatitis.

Lymphocytes from 12 of 17 patients with chronic active hepatitis were cytotoxic towards isolated hepatocytes in a microcytotoxicity assay. Enriched fractions of B cells, prepared by removal of E-rosetted cells, were cytotoxic in all 12 cases, whereas T-cell fractions, prepared by removal of erythrocyte-antibody-complement-rosetted cells, were cytotoxic in only 1 case (P less than 0-0005). HBsAg positive and negative cases reacted similarly. In 6 patients the addition of 5 mug aggregated IgG significantly reduced cytotoxicity from 54% +/- 15 to 13% +/- 15 (mean +/- 1S.D.) suggesting that K cells may be the effector cell in an antibody-dependent, cell-mediated reaction directed against a liver-specific membrane lipoprotein.