Ag processing by human circulating DC subsets. Human CD1c⁺ mDCs, CD16⁺ mDCs, BDCA3⁺ mDCs, and pDCs were incubated with the self-quenched model protein DQ-BSA and fluorescence, caused by uptake and subsequent degradation of DQ-BSA, was measured spectrophotometrically during 96 hours. (■) DCs were incubated with soluble DQ-BSA (A) or DQ-BSA encapsulated in PLGA particles (B). As a control, fluorescence of DCs only (·), or DCs activated with TLR ligands (▴; 4 μg/mL R848 for pDCs, 4 μg/mL R848 and 2 μg/mL poly(I:C) for mDC subsets) before adding DQ-BSA was measured. Data shown are mean ± SEM of 3 independent experiments performed in triplicate.