Treatment with bortezomib skews dextran uptake by DCs. (A) Adherent monocytes were incubated for 6 days in the presence of GM-CSF and IL-4. Cells were harvested and treated for 16 hours with bortezomib at the indicated concentrations. Thereafter, 2 × 10⁵ DCs were incubated with FITC-dextran for 1 hour at 37°C or at 4°C, washed 4 times, and analyzed by flow cytometry. Open histograms represent FITC-dextran–treated cells; solid histograms, cells incubated in the absence of FITC-dextran. Mean fluorescence intensity of DCs labeled with FITC-dextran at 37°C is shown.