Figure 5. Myeloid accessory cell cytokine-dependent NK cell activation.

Nonvaccinated control PBMCs, purified NK cells, or purified NK cells plus CD14⁺ monocyte–enriched population (mono) were stimulated with EBOV GP (A–C) (n = 5). PBMCs were also left unstimulated or stimulated with EBOV GP in the presence of blocking antibodies against IL-12 and IL-18 or appropriate isotype control (Iso.) (n = 16). NK cell function was analyzed by flow cytometry. Graphs show CD56^bright IFN-γ, CD107a, and CD25 expression (A–C), total NK cell CD25 MFI (D) or percentage (E), or CD56^bright CD25 MFI (F) or percentage (G), and total NK cell CD107a (H) and IFN-γ expression (I). Concentrations of IL-18 in culture supernatant and intracellular IL-12 expression were determined by ELISA and flow cytometry respectively, the relationship between IL-18 and total NK cell CD25 expression was determined by Spearman’s coefficient (J–L). IL-12(p40)⁺ B cells (CD19⁺), myeloid DC (mDC; CD19^–CD14^–CD11c⁺), total CD14^–, and total CD14⁺ cells were gated as per gating strategy in Supplemental Figure 5A. Graphs show box-and-whisker plots with median, IQR (box), and 10th to 90th percentile (whiskers) or 1 point per donor. Comparisons were performed using Wilcoxon signed-rank test and correlations were determined using Spearman’s correlation. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001.