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. 2012 May 18;7(5):e36928. doi: 10.1371/journal.pone.0036928

Figure 6. Cytokines secreted by poly I:C-treated macrophages play critical roles in NK cell activation.

Figure 6

The secretion levels of IL-12, IL-15, IL-18, IFN-β, or IFN-γ in the supernatants of RAW264.7 cells (A) or resident peritoneal macrophages from BALB/c mice (B) that were cultured with 0 or 100 µg/ml poly I:C for 24 h were analyzed by ELISA. The data are expressed as the mean ± SD from at least three separate experiments. *p<0.05, **p<0.01 compared with the untreated RAW264.7 group. NK cells were incubated with poly I:C-pretreated RAW264.7 cells in the presence of 10 µg/ml anti-IL-15 mAb, anti-IFN-β mAb or isotype control separately for another 12 h, and the expression of NKG2D were determined by flow cytometry (C). Levels of IFN-γ in the supernatants were determined by ELISA (D). NK cell-mediated lysis of YAC-1 cells was assessed by first culturing NK cells with poly I:C-treated RAW264.7 cells (Mφ) in the presence or absence of anti-IL-15 mAb, anti-IFN-β mAb or isotype control, respectively, and then NK cells were isolated and added to target cells (E). Data are expressed as the mean ± SD from at least three separate experiments. *p<0.05 compared with the isotype control group.