Effects of H2O2 treatment on the ability of pDCs to activate allogeneic T cells. Purified pDCs were treated with 0.01 µM H2O2 and R83 7, separately and in combination, for 24 h and then cocultured with allogeneic CD3+ pan-T cells. After 4 days of cocultivation, activation of CD3+ pan-T cells was assessed by IL-17, IFN-γ, and IL-4 ELISPOT assays. Spots indicate individual (A) IL-17-, (C) IFN-γ-, and (E) IL-4-producing T cells in representative assays from three independent experiments. (B, D, and F) Results are presented as means ±SE of three individual experiments. **P<0.01, ***P <0.001 vs T cells cocultured with untreated pDCs. ##P <0.01 vs T cells cocultured with R837-exposed pDCs. N/D, not detectable.