In this study primary hepatocyte cultures (HC cultures) and cocultures comprised of hepatocytes and Kupffer cells (HC/KC cocultures) were compared to investigate the inflammatory response induced by lipopolysaccharide (LPS). In addition both culture types were compared to study the hepatotoxic effects of two frequently used drugs: tiamulin and chlorpromazine. The inflammatory response in both culture types was determined by measurement of tumour necrosis factor-alpha (TNF-alpha), interleukin 6 (IL-6) and nitric oxide (NO). The drug-induced hepatotoxic effects were determined by measuring production of intracellular reactive oxygen species (ROS) and cytotoxicity. Exposure of both cultures to LPS resulted in a significantly increased production of TNF-alpha, IL-6 and NO. However, the production of TNF-alpha, IL-6 and NO was substantially increased in culture supernatant of cocultures, compared to single HC-cultures. Both tiamulin and chlorpromazine were potent inducers of intracellular ROS production at concentrations > or = 50 microM. High ROS production was paralleled by increased cytotoxicity as observed in both culture types. Incubation of cocultures with chlorpromazine resulted in a significant increased ROS production as compared to HC cultures. In contrast, no significant differences between HC-cultures and HC/KC cocultures were observed for tiamulin induced ROS production or cytotoxicity. The present study demonstrates that cocultures between Kupffer cells and hepatocytes provide an excellent model for the study of hepatotoxic compounds which exert (part) of their toxic effects via the activation of Kupffer cells. Furthermore they offer a valuable tool to study increased susceptibility to intoxication from xenobiotic agents in case of a concurrent or pre-existing inflammation.