Characterization of BMDC-derived exosomes. (A) Whole-mount preparations of DC exosomes show cup-shaped vesicles of 65 to100 nm diameter (×100 000; bar = 100 nm). (B) DC exosomes (arrows) attached to 4.5-μm beads used for flow cytometry. Inset: detail of exosomes (×150 000; bar = 100 nm). (C) Surface phenotype of DC exosomes by flow cytometry. DC exosomes concentrated molecules that were absent or expressed weakly on the surface of BMDCs (ie, CD14, CD178, membrane bound-TNF-α, and PS) and were negative for LAMP-1 (CD107a), a molecule confined to the limiting membrane of MVB. Open profiles indicate isotype controls. Numbers correspond to percentage of positive beads. Data are representative of 5 independent experiments.