Engagement of individual activation receptors on resting NK cells induces inside-out signals. Resting NK cells were mixed with target cells as indicated. Where indicated, S2 cells were preincubated with a rabbit anti-S2 serum (+ IgG). Cells were incubated for 5 minutes at 37°C, stained with conformation-specific, biotinylated anti–LFA-1 mAbs, washed, and stained with fluorochrome-conjugated anti-CD56 and streptavidin. (A-B) NK cells were gated on forward scatter/side scatter plots, and the profiles show CD56 versus 327C or mAb24 mAb staining, as indicated. Gates indicate the percentage of 327C^high or mAb24^high NK cells. The profiles are representative of 3 or more independent experiments. (C-D) The percentage of 327C^high or mAb24^high CD56^dim NK cells is presented as the mean of 6 donors. Bars indicate SD. *P < .01.