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Fig. 1 | Stem Cell Research & Therapy

Fig. 1

From: Human mesenchymal stromal/stem cells acquire immunostimulatory capacity upon cross-talk with natural killer cells and might improve the NK cell function of immunocompromised patients

Fig. 1

MSCs prime NK cells for increased IFN-γ release. a, b Purified NK cells from healthy volunteers were cultured in the absence (NK) or presence of MSCs (MSC/NK) for 24 h. a Cells were stimulated with IL-12 (1 ng/ml) and IL-18 (10 ng/ml). Unstimulated cells served as negative control. Twenty-four hours later, the content of IFN-γ in the supernatants was determined. b NK cells were harvested, washed, transferred into fresh plates, and stimulated or not with IL-12 and IL-18. The content of IFN-γ in the supernatants was quantified after 24 h. c Freshly isolated NK cells were cultured in the presence of conditioned media (CM) from NK cells, MSCs, MSC/NK cell co-cultures, and cell-free medium and were stimulated with IL-12 and IL-18. The release of IFN-γ into the supernatant was determined 24 h later. Bar graphs show mean ± SD of 4–5 replicates from one representative out of at least 12 independent experiments. Statistical analysis was performed using one-way ANOVA followed by Bonferroni multiple comparison test. d Flow cytometric analysis of intracellular IFN-γ synthesis in gated CD3CD56bright and CD3CD56dim NK cells stimulated with IL-12 and IL-18. Unstimulated cells served as negative control (–). The threshold of positive staining for IFN-γ was set according to the isotype control (iso). Numbers in the dot plots show the percentage of cells positive for IFN-γ. The median (interquartile range) of the percentage of IFN-γ+ cells among CD56bright NK cells was 58.3 (55.6–67; n = 7). **p < 0.01, ***p < 0.001. MSC mesenchymal stromal/stem cell, NK natural killer, IFN interferon

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