MSCs inhibit NK-mediated cytotoxic activity. Cytotoxic activity of one NK-cell population cultured with IL-2 for 6 days either alone (gray symbols) or in the presence of MSCs (black symbols) before the cytolytic assay against iDCs or SKNBE or MM6 tumor cell lines. In case of iDCs, NK cells were autologous with target cells. Data are representative of 5 different experiments, in which NK-cell populations derived from 5 different donors were used.