NO exposed SKO-007(J3) cells enhances NK cell-mediated cytotoxicity. A) NK cells prepared from PBMCs of healthy donors, were incubated with SKO-007(J3) cells, untreated or treated with DETA-NO for 48 h, 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. In order to evaluate the role of DNAM-1, the assay was performed in parallel treating NK cells with blocking anti-DNAM-1 antibody. Results are representative of one out of three independent experiments. B) The MFI of CD107 were calculated based on at least three independent experiments and evaluated by paired Student t test (*P < 0.05). Histograms represent the MFI with specific mAb subtracted from the MFI value of isotype control. C) NK cells isolated from PBMCs of healthy donors were incubated with SKO-007(J3) cells, untreated or treated with DETA-NO for 48 h as described above, and used as target cells in a standard 4-hour chromium-release assay. The percentage of specific lysis was calculated by counting an aliquot of supernatant and using the formula: 100 x [(sample release - spontaneous release)/total release - spontaneous release)]. All determinations were made in triplicate and E:T ratios ranged from 10:1 to 1:1, as indicated. Data represent the mean (n = 3 experiments, *P < 0.05).