Development and modification of a recombinant cell bioassay to directly detect halogenated and polycyclic aromatic...

Polycyclic and halogenated aromatic hydrocarbons (PAHs/HAHs) are a diverse group of widespread and persistent environmental contaminants that can cause a variety of detrimental effects in vertebrates. As most available methods to detect these contaminants are expensive, labor and time intensive, and require large amounts of tissue for extraction and analysis, several rapid mechanistically based bioassay systems have been developed to detect these chemicals. Here we describe application and optimization of a recently developed recombinant mouse cell bioassay system that responds to both PAHs and HAHs with the rapid induction of firefly luciferase for the detection of these chemicals in whole serum samples. This chemically activated luciferase expression (CALUX) bioassay has been modified to allow rapid (4-h) and direct analysis of small volumes (25-50 microl) of whole serum in a 96-well microtiter plate format without the need for solvent extraction. This bioassay can detect as little as 10 parts per trillion of the most potent HAH, 2,3,7,8-TCDD, and is also sensitive to other HAHs and PAHs. The use of simple procedures corrects for interplate and intraplate variability and the Ah receptor dependence of the induction response is accounted for by use of the antagonist 4-amino-3-methoxyflavone.