CD56^bright NK cells are suppressed in <i>Staphylococcus aureus</i>-induced IFN-γ synthesis after invasive surgery.

<p><b>(A-D)</b> PBMC were isolated from “patients 1” 24 h before (-1) and 1 d (+1), 5 d (+5), and 7 d (+7) after surgery and were stained against CD3 and CD56. <b>(A)</b> Gating strategy of CD3^-CD56^{<b>bright</b>} NK cells among total PBMC. The number indicates the percentage of gated cells in the rectangle. <b>(B)</b> Cumulative data on the percentage of gated CD3^-CD56^{<b>bright</b>} NK cells among total PBMC. <b>(C, D)</b> PBMC were cultured in the presence of <i>S</i>. <i>aureus</i> and cells were stained for intracellular IFN-γ. <b>(C)</b> Representative dot plots of intracellular IFN-γ expression in gated CD3^-CD5^{<b>bright</b>} NK cells isolated before and 1 d after injury. Numbers indicate the percentage of IFN-γ-positive (IFN-γ^<b>+</b>) cells. <b>(D)</b> Cumulative data on the kinetics of IFN-γ^<b>+</b> CD3^-CD56^{<b>bright</b>} NK cells upon exposure to <i>S</i>. <i>aureus</i> before and after injuy. <b>(E)</b> CD56^{<b>bright</b>} NK cells were purified from “patients 2” (n = 11) 1 d before and on day +1 after injury and stimulated with IL-12 and IL-18. The release of IFN-γ into the supernatant was quantified. Results are expressed as scatter plots (median, interquartile range). Statistical differences were tested using the Friedman test (B, D) or the Wilcoxon signed rank test (E). *, p<0.05; **, p<0.01; ***, p<0.001 vs. d-1. iso, isotype control antibodies.