Inhibition of IL-2–mediated survival by inactivating Syk and PI 3-kinase.
(A) NK92 cells, cultured in complete medium containing 100 U/mL IL-2, were incubated with 25 μM piceatannol or 25 μM LY294002 or DMSO vehicle control and were examined for cell viability by trypan blue exclusion at 0, 24, 48, and 72 hours. Experiments were performed in triplicate. The percentage of viable cells calculated per experiment is shown (P < .05). (B) NK92 cells, obtained from cultures described in panel A, were examined for morphologic changes at 24 hours. Experiments were performed in triplicate. The percentage of apoptotic cells and total number of cells counted per experiment are shown at the bottom of each panel. Statistical analysis using a χ2 test revealed that piceatannol and LY294002 significantly induced apoptotic morphology in NK cells (P < .05). Nuclear condensation and nuclear body (arrow) are indicated. (C) NK92 cells, obtained from cultures described in panel A, were examined for apoptosis by annexin V–FITC binding and PI uptake. Cells were collected at 24 and 48 hours in each experiment, washed in sample wash buffer, and stained with annexin V–FITC in combination with PI. Annexin V–FITC binding in piceatannol-, LY294002-, or DMSO-treated and untreated NK92 cells is shown.
