FITC-DX uptake by CD11b^−/dullCD11c⁺ precursors (▧) and CD11b^+hiCD11c⁺ DC precursors (▧) at day 6 and their derived CD11b^−/dullCD11c⁺ mature DCs at days 12 to 14. Cells were first exposed to 0.1 mg/mL of FITC-DX at 0°C and 37°C, respectively, for 60 minutes. After washing twice, the cells were stained with rat–anti-mouse CD11b and biotinylated hamster–anti-mouse CD11c and then shown by PE-conjugated anti-rat Ig and CY-conjugated-streptavidin. A three-color immunofluorescence analysis was performed to show the capacity of FITC-DX uptake by these cells as indicated. *P < .01 significance compared with CD11b^−/dullCD11c⁺ (▥) and CD11b^+hiCD11c⁺ (□) DC precursor-derived mature DCs. Results are representative of three experiments.