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. Author manuscript; available in PMC: 2015 Apr 1.
Published in final edited form as: Biol Blood Marrow Transplant. 2014 Jan 13;20(4):463–473. doi: 10.1016/j.bbmt.2014.01.006

Figure 1. CD25 expression is induced on human NK cells by combined cytokine activation.

Figure 1

Freshly purified human NK cells were stained for baseline CD25 expression, and activated overnight with the following cytokines (1 ng/mL IL-15, LD15; 1 nM IL-2; 100 ng/mL IL-15; 10 ng/mL IL-12; 50 ng/mL IL-18) or combinations of the cytokines as indicated. After culture for 16 hours, cells were washed extensively and cultured for an additional 3 or 7 days in LD15 for all later time points. (A) Cell surface CD25 is induced following activation with IL-12, IL-15, and IL-18, compared to LD15, on NK cells. Representative flow histograms at baseline, 16 hours, 3 days, or 7 days after the initiation of IL-12, IL-15, and IL-18 pre-activation or culture in LD15, demonstrating the marked increase and prolonged expression of CD25. (B and C) CD25 percentage (B) and mean fluorescence intensity (MFI) (C) of NK cells at various time points following cytokine activation. Summary data represents n=6 donors (3 independent experiments). Data shown is mean ± SEM of percentage or the MFI of CD25+ NK cells. Significance is shown comparing each time point versus fresh (baseline) NK cells, and was calculated by one-way ANOVA. These data show that while individually IL-2, IL-12, IL-15, and IL-18 induce CD25+ CD56dim NK cells, the combinations of IL-15+IL-18 and IL-12+IL-18 result in higher per cell CD25 expression.