Transient interactions between NK cells and the DC network during the course of NK-cell priming. Ncr1^GFP/+ × CD11c-YFP mice were injected intravenously with poly I:C. At various time points, popliteal LNs were imaged by 2-photon microscopy. Individual NK cells were analyzed over time for interactions with DCs. (A) Contact histories for individual NK cells. Red squares correspond to time points at which the analyzed NK cell contacted a DC. Black squares correspond to time point at which the NK cells showed no apparent interaction with the DC network. Each square corresponds to a 30-second interval. (B) The percentage of time spent by individual NK cells in contact with DCs is compiled at various time points after poly I:C injection. Mean values are shown as black bars. (C) The duration of individual NK cell–DC contacts is graphed for the various time points analyzed. Results are representative of 3 independent experiments.