DOCK2 controls TLR7/9-mediated type I IFN induction in pDCs via Rac activation. (A) The uptake of CpG-A was compared between WT and Dock2^−/− pDCs after cells were incubated with 3 µM CpG-A–Cy5 at 37°C (filled area) or 4°C (open area) for 1 h. Before assay, cell surface fluorescence was quenched with 0.2% trypan blue. Representative profiles of three independent experiments are shown. (B and C) BM-derived pDCs from WT, Dock2^−/−, and Tlr9^−/− mice were stimulated with 3 µM CpG-A for the indicated times (B) or CpG-A–coated polystyrene beads for 1 min (C). Cells were then fixed and stained with phalloidin. Representative images of two independent experiments are shown. DIC, differential interference contrast. Bars, 10 µm. (D–G) Activation of Rac was analyzed for BM-derived pDCs from WT (+/+), Dock2^−/−, and Tlr9^−/− mice after stimulation with 3 µM CpG-A (D), 100 nM R848 (E), influenza A virus, or HSV-2 at a MOI of 0.5 (F) or 2.18 µg/ml HSV-2 DNA (G) for the indicated times. Data are representative of three (D and F) or two (E and G) independent experiments. (H and I) BM-derived WT pDCs were retrovirally transduced to express either T17N-Rac–IRES–GFP or WT Rac–IRES–GFP. After fluorescence-activated cell sorting, GFP-positive cells (H, 4 × 10⁴ cells per well; I, 6 × 10⁴ cells per well) were stimulated with 3 µM CpG-A (H) or influenza A virus at an MOI of 0.5 (I) for 24 h. Data indicate the levels of IFN-α and IL-12p40 in cell culture supernatants (mean ± SD of triplicate wells) and are representative of five (H) and two (I) independent experiments. **, P < 0.001; *, P < 0.01. ND indicates below the detectable limit.