An aryl hydrocarbon receptor independent mechanism of JP-8 jet fuel immunotoxicity in Ah-responsive and Ah-nonresponsive mice

JP-8 jet fuel is handled extensively by personnel in the military and commercial airlines, despite the paucity of information regarding its potential human health effects. JP-8 is a complex mixture primarily consisting of kerosene plus aliphatic and aromatic hydrocarbons. Recent reports indicate that acute JP-8 exposure via inhalation or dermal routes can overtly and persistently impair immune function in mice. Data from preliminary studies in this laboratory assessing the immunotoxicity of JP-8 indicated that oral JP-8 exposure caused an increase in liver weight, a decrease in thymus weight, and a decrease in the PFC response. As these results were similar to classic effects elicited by TCDD, a strong AhR ligand, it was hypothesized that JP-8 may exert immunosuppression via a similar mechanism. To test this hypothesis, an Ah-responsive mouse strain (B6C3F1) and a classically non-responsive mouse strain (DBA/2) bearing a lower affinity AhR were gavaged with JP-8 for 7 days. The results suggest that both mouse strains were equally sensitive to JP-8's toxicity at several endpoints including thymus weight and cellularity, liver weight, and specific IgM antibody responses. Furthermore, JP-8 did not induce CYP1A1 or promote down regulation of the AhR when evaluated by Western blot in either B6C3F1 or DBA/2 mice. In vitro studies corroborated these findings as JP-8 did not induce CYP1A1, promote down regulation of the AhR, or activate an XRE-driven reporter gene in murine Hepa-1 cells. These results suggest that JP-8 may exert its toxicity via an AhR-independent mechanism.