The CD56^bright NK-cell subset in PB is mainly responsible for mediating monocyte differentiation into DCs. The CD56^bright and CD56^dim PB-NK-cell subsets were sorted as shown in the contour graphs (top panels). The purified NK-cell subsets were thereafter cocultured with CD14⁺ monocytes in the presence of IL-15 at a 10:1 ratio (monocyte/NK cell) for 6 days. Cell surface expression of CD14, CD86, CD80, DC-SIGN, CD40, and CD83 was analyzed after monocyte culture in the presence of IL-15 alone (filled dark gray histogram) or after coculture with CD56^bright NK cells (solid line) or with CD56^dim NK cells (dotted line). The filled light gray histograms show the isotype control stainings. Data are representative of 3 separate experiments.