Inside-out signals on resting NK cells are inhibited by CD94/NKG2A engagement. Resting, NKG2C-depleted 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 mAb 327C, washed, and then stained with fluorochrome-conjugated anti-CD56, anti-NKG2A, and streptavidin. (A) NK cells were gated on forward scatter/side scatter plots and CD56^dim expression. Where indicated, S2 cells were preincubated with peptides sp B*27 (blue) or sp C*03 (red). The profiles show NKG2A versus 327C mAb staining on CD56^dim NK cells. Numbers indicate the percentage of 327C^high CD56^dim NK cells within the respective gates. (B) The percentage of 327C^high CD56^dim NK cells is presented as the mean of 4 donors. Bars indicate SD. *P < .05. Experiments are representative of at least 3 independent experiments.