Fig. 1.

Characterization of exosomes from metastatic melanoma cell lines. Exosomes from Ma-Mel-86c cells were purified from tissue culture supernatant by ultracentrifugation. a TEM. Exosomes were analyzed by electron microscopy. Bar: 100 nm. b Western blot. MICA and tetraspanins (CD63, CD81 and CD9) were analysed by Western blot. Actin was used as loading control. The result from a representative experiment is shown. An exposure of 10–15 s is shown in the right panel. c NKG2D downmodulation. Activated NK cells were co-incubated with increasing amounts of Ma-Mel-86c exosomes as indicated. Cells were stained with anti-NKG2D and analysed by flow cytometry. The plot represents the change in the mean fluorescence intensity (MFI) of NKG2D on NK cells after incubation with exosomes, related to NK cells incubated in medium alone. Data are the mean and SEM obtained in three experiments using NK cells from different donors (*P < 0.05)