HUMAN HEPATOCYTES EXPRESS TRIFLUOROACETYLATED NEOANTIGENS AFTER IN-VITRO EXPOSURE TO HALOTHANE

Biotransformation of anaesthetic halothane by cytochrome P450-dependen t monooxygenases resulted in the production of reactive intermediate t rifluoroacetyl (TFA) halide, capable of covalently binding to hepatocy te proteins. TFA-modified liver proteins can act as antigens and are i mplicated in the pathogenesis of halothane hepatitis in humans. The ai m of this study was to investigate the formation of TFA-neoantigens in halothane-treated primary cultures of adult human hepatocytes and to evaluate the usefulness of this in vitro model for studying immune-med iated halothane hepatotoxicity. Cultured human hepatocytes were incuba ted with halothane under constant temperature, atmosphere and anaesthe tic concentration conditions. The results obtained show that halothane -treated hepatocytes isolated from seven different donors produced TFA -antigens as detected by immunocytochemical and western immunoblot ana lysis using rabbit anti-TFA antiserum. TFA-adducts were localized main ly in the endoplasmic reticulum and in small amounts on the plasma mem brane of parenchymal cells. By immunoblotting, several neoantigens, wi th molecular masses from 42 to 100 kDa, were detected in halothane-exp osed hepatocytes. These observations are consistent with the formation of TFA-adducts through metabolism of the anaesthetic and suggest that primary cultures of human hepatocytes represent a suitable in vitro m odel to study the pathogenesis of immune-mediated halothane hepatotoxi city.