Doxorubicin or melphalan treatment of SKO-007(J3) cells increases NK-cell degranulation in an NKG2D- and DNAM-1–dependent manner. NK cells derived from PBMCs of healthy donors, preactivated with 200 U/mL IL-2 for 12 hours, were incubated with SKO-007(J3) cells, untreated or treated as described in the legend of Figure 1, and used as target cells in a degranulation assay. The assay was performed at the effector-target (E/T) ratio of 2.5:1. After 2 hours at 37°C, cells were stained with anti-CD56, anti-CD3, and anti-CD107a mAbs. Cell surface expression of CD107a was analyzed on CD56⁺CD3⁻ cells. To evaluate the role of NKG2D and DNAM-1, the assay was performed also treating NK cells with blocking anti–DNAM-1, anti-NKG2D, or anti-CD56 mAb used as control. Results are expressed as the percentage of CD107a⁺ cells obtained by subtracting the percentage of isotype control antibody, and are representative of 1 of 4 independent experiments. Data are presented as the means plus or minus SD of triplicates. Antibody blocking on drug-treated cells always showed a statistically significant increase in CD107a expression, compared with drug-treated cells with no Ab or control Ab (P < .05 or P < .005). A statistically significant difference was also observed between NT versus drug-treated samples for no Ab (P < .05). All other combinations were not significant.