Ionomycin treatment reduces the degranulation and killing ability of NK cells.

<p>(<b>A</b>) Primary NK cells were treated with 1 μM ionomycin, or DMSO as control, during 16 hours, and after resting for 24 h, their ability to degranulate in response to K562 cells (Lamp1⁺ NK cells) was analyzed. (<b>B</b>) The induction of NK cell unresponsiveness depends on the dose of ionomycin used (0.25 μM to 2 μM) in a 16 hours treatment, and the duration of the treatment (2 to 16 hours). Data represent the percentage reduction of Lamp1⁺ NK cells in ionomycin treated cells compared to control, DMSO exposed, cells. (<i>n = 5</i>). One way ANOVA and Bonferroni post-test analysis were used to calculate statistical significance, using the logarithms of crude data. (<b>C</b>) Flow cytometry analysis shows that ionomycin-treated NK cells degranulate during 2 hours much more efficently in response to PMA/ionomycin rather than K562 cells (<i>n = 10</i>). Two tailed paired Student's T test analysis. (<b>D</b>) Ionomycin-treated NK cells respond poorly to a range of different target cells during 2 hours (<i>n = 6</i>). Two tailed paired Student's T test analysis. Whiskers show minimum to maximum data. (<b>E</b>) Reduced NK cytotoxicity measured by flow cytometry of ionomycin-treated NK cells (<i>n = 4</i>). Two way paired ANOVA analysis and Bonferroni post-test. Data show mean ± SEM (with the exception of D), *<i>p</i> < 0.05, **<i>p</i> < 0.01, ***<i>p</i> < 0.001.