Activation of NK cells by DCs. Allogeneic and autologous non-adherent PBMCs were cocultured with DCs at a ratio of 10:1 for 24 h. Cells were stained for CD3, CD56, CD69 and IFN-γ expression and analyzed by flow cytometry. (A) Shown is the percentage of CD69 expression on CD3-/CD56+ gated NK cells. Representative histograms of unstimulated NK cells, IL-2 (500 IU/mL) activated NK cells, DCs + autologous NK cells (upper panel) and DCs + allogeneic NK cells (lower panel) of one AML patient are shown (cocktail R was used for DC maturation). The dot blots below show the corresponding intracellular IFN-γ staining, with PMA/ionomycin serving as a positive control. (B) Summary of the percentage of CD69 expression on CD3-/CD56+ NK cells after coculture with allogeneic and autologous NK cells from HC and AML patients. (C) Production of IFN-γ after coculture of DCs and isolated NK cells was assessed by ELISA. DCs were generated and cocultured with allogeneic NK cells at a ratio of 1:10 for 24 h. Supernatant was analyzed by standard ELISA for IFN-γ. The comparison of HC and AML patients is shown using the four different maturation cocktails. As a positive control NK cells were stimulated with IL-2.