In vitro response of fish and mammalian cells to complex mixtures of polychlorinated naphthalenes, polychlorinated biphenyls, and polycyclic aromatichydrocarbons

In vitro characterization and comparison of responses to different classes of biologically active compounds can increase the utility of bioassays. In this study, the relative potencies (REPs) of mixtures of polychlorinated na phthalenes (PCNs), polychlorinated biphenyls (PCBs), and polycyclic aromati c hydrocarbons (PAHs), to induce in vitro ethoxyresorufin-O-deethylase (ERO D) in PLHC-1 fish hepatoma cells, H4IIE wild type (H4IIE-wt) rat hepatoma c ells, and recombinant H4IIE cells (H4IIE-EROD) were determined. The mixture s were also analyzed by in vitro luciferase assay with recombinant H4IIE ce lls (H4IIE-luc). Halowaxes 1051, 1014, and 1013 caused significant inductio n in all three H4IIE assays at concentrations less than 10 mg/l, but did no t elicit a significant response in the PLHC-1 assay. Based on H4IIE results , the Halowaxes were estimated to have relative potencies (REPs) of approxi mately 10(-6)-10 (8) relative to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) . Less than 5 mg/l of Aroclors 1242, 1248, 1254; Clophens A60, T64; and Chl orofen induced significant responses in the H4IIE assays, while only Clophe ns A60 and T64 caused a significant response in the PLHC-1 assay, The effic acy of the Aroclor mixtures was generally insufficient to allow for quantit ative REP estimates, but, based on their responses in the H4IIE assays, Clo phen A60 and Chlorofen were estimated to have REPs of approximately 10 (6) and 10(-7), respectively. A mixture of 16 priority PAHs caused significant induction in all four cell types and was estimated to have a REP of approxi mately 10(-4). Overall, the results of this study add to a growing database on the dioxin-like potency of complex mixtures of xenobiotics, and suggest ed that H4IIE-based in vitro bioassays were more sensitive than PLHC-1 cell s for detecting dioxin-like activity in complex mixtures. (C) 2000 Elsevier Science B.V. All rights reserved.