Effect of inducers of P-450 cytochrome isoenzymes on TCDD immunosuppressive activity

Drugs inducing different forms of P-450 cytochrome isoenzymes and binding the Ah receptor or not were investigated for their ability to modify 2,3,7,8, tetrachlorodibenzo-p-dioxin (TCDD) immunotoxicity in mice. 3-Methyl-cholanthrene (3MC) and β-naphthoflavone (BNF) administered to TCDD-treated mice caused additive inhibition of humoral antibody production and of responsiveness to concanavallin A (ConA) but not to phytohemagglutinin (PHA) and lipopolisaccharide (LPS) while phenobarbital (PB) never modified TCDD immunosuppression. Natural killer (NK) cell activity was not reduced by single drug treatment or by combined treatments. Hepatic aryl hydrocarbon hydroxylase (AHH) induction by TCDD was not significantly modified by PB, 3MC or BNF.