Fig. 5
Monocyte chemotactic proteins promote IFN-γ production in NK cells. NK cells were incubated in the absence (–) or presence of recombinant human CCL2, CCL8, CCL7, and CCL12, or with conditioned medium (CM) from MSCs for 12 h. Thereafter, the cells were stimulated with suboptimal concentrations of IL-12 (1 ng/ml) and IL-18 (5 ng/ml) or left unstimulated. a After 24 h the content of IFN-γ in the supernatant was determined. Bar graph showing mean ± SD of 4–5 replicates of one representative out of five independent experiments. Statistical analysis was performed using one-way ANOVA followed by Bonferroni multiple comparison test. b Dot plots of intracellular staining of IFN-γ in gated CD3–CD56bright NK cell (gating strategy as shown in Fig. 1d) after stimulation with IL-12 and IL-18. The threshold of positive staining for IFN-γ was set according to the isotype control (iso). Numbers indicate the percentage of IFN-γ-positive NK cells. c Cumulative data on the percentage of IFN-γ+CD56bright NK cells from five donors after normalization to the percentage of cells stimulated with IL-12/IL-18 in the absence of CCL (set as 100 %). Vertical lines indicate the median and interquartile range. ***p < 0.001, **p < 0.01. CCL C-C chemokine ligand, IFN interferon, MSC mesenchymal stromal/stem cell