Kinetics of inhibition of in vitro interferon-alpha/beta production after benzo-(a)-pyrene exposure

L-929 cells were treated with benzo-(a)-pyrene (BP), washed, and then interferon(IFN)-alpha/beta was induced with polyriboinosinic-polyribocytidylic acid (poly-I-C). IFN-alpha/beta production by these cells was measured at 6-hour intervals. Up to 24 h after commencement of IFN induction, IFN production was severely inhibited in BP-treated cells as compared to controls. After 24 h, IFN-alpha/beta production in BP-treated cells began to rise and reached levels seen in untreated cells by 48 h. These data indicated that IFN induction was not completely inhibited by BP treatment, but, rather, the peak of IFN production was delayed. Mouse embryo cultures from SENCAR mice showed the same pattern of delayed IFN production when treated with BP. Direct exposure of the cells to BP for at least 15 min prior to removal of the carcinogen was required for IFN induction to be inhibited; however, at least 24 h of further incubation in fresh medium before addition of poly-I-C was required for inhibition of IFN induction by BP.