Kinetics of activation of benzo[a]pyrene for inhibition of interferon induction

The induction of interferon-alpha/beta (IFN-alpha/beta) by polyribosinosinic-polyribocytidylic acid was inhibited when murine L-929 cells were pretreated with the carcinogen benzo[a]pyrene (BP). Exposure of L-929 cells for 24 hr to BP was required to inhibit IFN-alpha/beta induction. When the BP was activated to the ultimate carcinogenic form in an in vitro cell-free liver microsomal enzyme system, the exposure time of L-929 cells to BP required for inhibition of IFN induction was decreased to 3 hr. BP dosages required for inhibition of IFN induction were not altered when the BP was preactivated, and the degree of inhibition of interferon induction was related to the concentration of microsomal enzymes added to the cell-free activation system.