DMBA and TCDD suppress LPS-induced IL-6 protein production. BMS2 cells were plated 250,000 cells per flask and cultured for 18–24 hours prior to treatment with vehicle (0.01% ethanol), 1 μM DMBA, or 1 nM TCDD. One hour later, cultures were challenged with 1 μg/ml LPS as indicated. Supernatants were sampled at various times thereafter and assayed by ELISA for IL-6 protein levels. IL-6 concentrations were determined by comparison to a recombinant IL-6 standard curve. Data are presented as means ± SE from three independent experiments. IL-6 levels for each time point within an experiment were measured in triplicate (A) IL-6 levels in groups not challenged with LPS. *Significantly different from vehicle control, p < 0.05 (one-way ANOVA and Dunnett's multiple comparisons test). **Significantly different from vehicle control, p < 0.01. (B) IL-6 levels in groups challenged with LPS. *Significantly different from corresponding LPS-plus-vehicle wells (p < 0.05). **Significantly different from vehicle or vehicle-plus-LPS wells, p < 0.01.