OBJECTIVETo investigate the effect of myeloma-derived exosomes on surface activating receptors of NK cells, and to explore the mechanism of the function defect of NK cells.

METHODSThe exosomes from the supernatant of multiple myeloma cell lines RPMI8226 and U266 were extracted by ultracentrifugation, and the size of them was identified under electron microscope; the human primary NK cells were extracted, and were co-cultured with the myeloma-derived exosomes (40 µg/ml), then the expression levels of surface activating receptors NKp46, NKp30 and NKG2D of NK cells at 0,1,4 and 24 hours were detected by flow cytometry.

RESULTSThe exosomes showed small vesicular, sized 30-100 nm under electron microscope. The expression of surface activating receptors of NK cells declined at different degree after co-cultured with myeloma-derived exosomes.

CONCLUSIONMyeloma-derived exosomes can inhibit the expression of surface activating receptors of NK cells.