Cytochrome P450 1A1 and 4A activities in isolated rat spleen lymphocytes

In this study the activity of Cytochrome P 450 (CYP) enzymes in isolated spleen lymphocytes of Wistar rats was estimated. 7-Ethoxyresorufin-O-deethylase was analysed to determine the activity of CYP 1A1/2. The activity was increased 2.2-fold by pretreating the animals with 3-methylcholanthrene, and 1.3-fold after the addition of the mitogen concanavalin A to the lymphocyte culture. Pretreatment of the rats with phenobarbitone did not enhance the basal enzyme activity. To estimate reductive activities the azoreduction of 4-(N,N-dimethyl-amino)azobenzene was analysed. Again detectable turnovers were found which could be increased 4-fold after the addition of concanavalin A. Azo-reductase activity could also be increased 2-fold after clofibrate was added to the lymphocyte cultures, and was decreased by adding metyrapone so that it was concluded that azoreduction may be partly due to the CYP 4A-family.