DD treatment modulates DC function in vitro. (A) imDC and maDC were generated in vitro (see “Materials and methods” for details) and were incubated with increasing doses of DD (as indicated) for 48 hours. Subsequently, cells were labeled with annexin V and analyzed by FACS. Error bars (standard deviation, SD) were calculated on the basis of triplicates of 1 representative experiment (3 performed). (B) MLR using DD pretreated imDC and maDC (48 hours; 0, 10, 100, and 1000 ng/mL) and allogeneic CD4 T cells at different DC: T-cell ratios as indicated. Dead DCs were excluded by trypan blue staining. (C) MLR with DD-pretreated maDC and allogeneic CD4 T cells (1:20 ratio), supplemented with resting or activated T_reg (autologous to maDC). (D) Surface levels of different receptors on maDC and imDC after DD treatment (0, 10, and 100 ng/mL) for 48 hours. Intracellular levels are shown in supplemental Figure 6. Data in (C) and (D) are shown as mean values ± standard error of 4 independent experiments using PBMC from different healthy donors. P values were calculated with the Student t test (*P < .05; **P < .01).