Figure 1.

IL-15–stimulated NK cells induce monocyte differentiation into DC_NK in vitro. (A) Phase contrast microscopy (original magnification, ×100; 10×/0.30 phase objective lens) pictures showing (left to right): monocytes cultured for 6 days in medium alone, monocytes cocultured with NK cells in medium alone, monocytes cultured in the presence of IL-15, or monocytes cultured with NK cells in the presence of IL-15, as indicated on the top of each picture. Images were acquired at 25°C using the equipment described in “Antibodies, enzyme-linked immunosorbent assay, and immunofluorescence,” are representative of 5 separate experiments. (B) Histograms show the phenotype of monocytes after culture in medium alone (black line), or in the presence of IL-15 (blue line), and monocytes that have been cocultured with NK cells in medium alone (red line), or in the presence of IL-15 (green line). The gray histogram represents the isotype control staining of monocytes that have been cocultured with NK cells in the presence of IL-15 (ie DC_NK). The data are representative of 3 separate experiments. (C) Light microscopy (left panels) of DCs generated from monocytes upon NK-cell coculture (DC_NK bottom) or DCs generated from monocytes in the presence of GM-CSF and IL-4 (DC_GM/IL4 top). The DCs were surface stained with anti–HLA-DR (FITC, middle panels) and intracellular DC-LAMP (PE, right panels) and imaged by fluorescence microscopy (original magnification, ×630; 63×/1.40-0.60 oil-immersion objective lens). The results shown are representative of 2 separate experiments.