Figure 2. Vorinostat inhibits APC activation and IFN-α production by plasmacytoid dendritic cells.

A: Peripheral blood mononuclear cells from healthy volunteers were cultured in 24-well plates at a density of 2×10⁶ /ml/well in media alone, with 1µM vorinostat, or 10µg/ml synthetic TLR 7/8 agonist 3M-007 for 48h, or primed with 1µM vorinostat for 4h followed by activation with TLR 7/8 agonist for further 48h. Cells were then harvested, and analyzed for the expression of CD80. Monocytes were identified by anti-CD64 and anti-CD14 staining. Plasmacytoid dendritic cells (pDCs) were defined as lineage-negative cells (Lin 1-FITC cocktail) that co-express HLADR and CD123. Myeloid dendritic cells (mDCs) were defined as lineage-negative cells co-expressing HLADR and CD11c. The figure illustrated one of three representative experiments. B: Peripheral blood mononuclear cells from healthy volunteers were cultured in 24-well plates at a density of 2×10⁶ /ml/well in media alone, with 1µM vorinostat, or 10µg/ml synthetic TLR 7/8 agonist 3M-007 for 48h, or primed with 1µM vorinostat for 4h followed by activation with TLR 7/8 agonist for further 48h. Cell free supernatants were then collected, and IFN-α levels were measured in cell-free supernatants by ELISA. Data represent mean ±SD of tested individuals. *p <0.05 compared to the TLR 7/8 agonist sample.