Induction of DC maturation by NK cells involves NKp30 receptor engagement. Immature DCs were cocultured with an allogeneic polyclonal NK-cell line for 2 days in the absence or in the presence of anti-NKp30 mAb or anti-CD56 mAb (both of IgM isotype). Controls included iDCs cultured either in medium alone or in the presence of LPS (1 μg/mL) or in the presence of both LPS and anti-NKp30 mAb. DCs were then analyzed by indirect immunofluorescence and cytofluorometric analysis for expression of CD83 and CD86. The percent of positive cells is indicated. Horizontal bars represent markers assigned on the basis of control cells fluorescence intensity (ie, cells incubated with the second reagent alone). Results are representative of 6 independent experiments.