ABSTRACT
<p><b>OBJECTIVE</b>To 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.</p><p><b>METHODS</b>The 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.</p><p><b>RESULTS</b>The 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.</p><p><b>CONCLUSION</b>Myeloma-derived exosomes can inhibit the expression of surface activating receptors of NK cells.</p>