HDAC inhibitors inhibit the response of DCs to microbial stimulation. (A-C) BMDCs were preincubated for 1 hour with TSA before stimulation for 18 hours or the indicated time with LPS (100 ng/mL), Pam₃CSK₄ (100 ng/mL), CpG oligonucleotide (CpG, 0.7μM), and heat-killed C albicans, E coli, or S aureus (10⁷ CFU/mL). (A-B) IL-6 and IL-12p40 production. Data are mean ± SD of triplicate samples and are representative of 4 independent experiments. (C) Cd40 mRNA expression quantified by RT-PCR. Results are expressed as the ratio of Cd40 mRNA level to that of GAPDH. Data are mean ± SD of 1 experiment representative of 3 independent experiments. AU indicates arbitrary units. (D) CD40 mean fluorescence intensity (MFI) determined by flow cytometry. Data are representative of 3 independent experiments. (E-G) Human moDCs were preincubated for 1 hour with TSA (E-F, 100nM) or VPA (E-F, 100μM) before exposure to LPS (30 ng/mL) for 18 hours. (E) TNF and IL-6 production. Data are mean ± SD of triplicate samples and are representative of 2 independent experiments. (F) Effect of TSA and VPA on cytokine and chemokine production by 2 independent preparations of moDCs. Mediators were analyzed using the Luminex technology (“Cytokine measurements”). + indicates inhibition (fold change > 2); and −, no effect. (G) CD40, CD80, CD86, and CCR7 expression analyzed by flow cytometry. Data are representative of 2 independent experiments.