Selective phagocytosis of nanoparticles by pDCs. Fresh human PBMCs were incubated for 4 hours with 10 μg/mL fluorescent nanospheres (A) or for 6 hours with 20 μg/mL protamine-RNA particles (B), then stained with antibody specific for BDCA-2 and, in panel B, anti–interferon-α fluorescein isothiocyanate antibody. Cells were analyzed by fluorescence-activated cell sorting. The value in each quadrant indicates the percentage of cells as a percentage of the parent gate. The data shown are representative of 4 independent experiments.