PrA inhibited DC maturation responding to LPS and diminished DC-mediated T cell allostimulation.

<p>DCs (Wistar) were treated with LPS alone or LPS plus PrA (5, 20, or 40 nM) from days 7 to 9 in vitro. (A) DC viability was measured at each concentration using the MTT assay. The highest dose induced a significant decrease in viable DC count, so only 5 nM and 20 nM were used in subsequent experiments. (B, C, D) LPS-induced maturation of DCs was examined by immunolabeling for OX62, CD80, and CD86 and subsequent FACS. Treatment with PrA suppressed the LPS-stimulated expression of these DC markers. (E) The proliferation of SD T cells in MLR coculture with mitomycin C-pretreated Wistar DCs (as stimulator) at DC∶T plating ratios of 1∶10, 1∶20, 1∶50, and 1∶100 was measured by Brdu incorporation. PrA-treated DC displayed much inferior T cell allostimulatory activity in MLR using 1×10⁶ SD T cells as responders. (F, G) IL-12p70 and IL-10 production in MLR coculture supernatant (DC and T cells ratio of 1∶10) were assessed by ELISA. Data are shown as the means±SD of three independent experiments (A, C–G; n = 3). Similar results were obtained in three independent experiments (B; n = 3). *P<0.05 and **P<0.01 compared with the LPS-DC (no PrA) control group. ^#P<0.05, compared with the T cells only (no DC) group.