Increased sensitivity of monocyte-derived dendritic cells (mo-DCs) to benzo( a )pyrene (B a P) stimulation. (A) The expression of aryl hydrocarbon receptor ( AHR) and CYP1A1 in human peripheral blood (PB) CD3+ T cells, CD20+ B cells, CD14+ monocytes and mo-DCs. Gene expression was analyzed using qRT-PCR. All mRNA levels are expressed relative to glyceraldehede-3-phosphate dehydrogenase (GAPDH). Data are the mean ± standard error of the mean (SEM) (n = 2). (B) Comparison of the dose-dependent response of CD14+ monocytes and mo-DCs to (0.01-10μM) BaP stimulation (24 hr). Data are representative of three experiments with cells purified or derived from the same PB sample. Comparison of AHR and CYP1A1 gene expression in (C) CD14+ monocytes and (D) mo-DCs when stimulated with varied concentrations (1 - 10μM) of BaP (24 hr), 10μM phorbol 12-myristate 13 acetate (PMA) (72 hr; monocytes), or polyinosinic:polycytidylic acid (PolyI:C) (24 hr; mo-DCs) treatment. Data are the mean ± SEM (n = 3) relative to AHR and CYP1A1 mRNA levels found in untreated cells (UNT), arbitrarily set at a value of 1 with cells purified or derived from the same PB sample. (E) Expression of IL6 and (F) IDO1 in response to 3μM BaP (24 hr) or PolyI:C (24 hr) alone, or in combination (as indicated). n.d., not detected. Data are the mean SEM from 3 experiments. *P < 0.05, **P < 0.01, Tukey multiple comparison test.