Localization of halothane-induced antigen in situ by specific anti-halothane metabolite antibodies

Multiple or single halothane exposure of rabbits or guinea pigs induces an antibody reactive with trifluoroacetylated (TFA) proteins. The antigen that initiates this immune response was investigated in halothane-exposed rabbits and guinea pigs for its anatomical location in the liver, the chronology of its expression in situ and exposure conditions which would modulate its expression. Using an immuno-staining technique, binding by an anti-TFA antibody to the antigen was detected in liver tissue from all halothane-exposed rabbits and guinea pigs. Antigen could be detected only in the centrilobular area around the central vein where staining intensity was concentrated in an area seven to nine cells deep. In halothane-exposed rabbits, the appearance of TFA antigen was most predominant on the first and second days following a single exposure. Multiple exposures induced TFA antigen in a larger area around the central vein than did a single exposure. Though maximal expression of TFA antigen occurred following two or three exposures, subsequent exposures did not potentiate antigen expression. In halothane-exposed guinea pigs, exposure to deuterated halothane, which reduces the extent and metabolites of oxidative halothane metabolism, elicited the appearance of TFA antigen around the central veins, although to a lesser extent than during halothane exposure. Halothane-induced antigen was evident in guinea pigs as early as 6 h post-exposure and was still apparent 90 h later. Thus, halothane exposure by inhalation elicits the appearance of TFA protein conjugates which may, in turn, evoke the anti-TFA immune response.