Resting NK-cell degranulation induced by 2B4 and NKG2D synergy or CD16 is inhibited by CD94/NKG2A engagement. Resting NK cells were mixed with S2, S2–HLA-E, or S2–CD48–ULBP1–HLA-E that had been preincubated with peptides as specified. For Fc-receptor stimulation, S2 cells were also preincubated with a rabbit anti-S2 serum (+ IgG). Cells were incubated for 2 hours at 37°C, then stained with fluorochrome-conjugated anti-CD56, anti-CD107a, and anti-NKG2A mAbs. NK cells were gated on forward scatter/side scatter plots and CD56^dim expression. (A) The profiles show NKG2A versus CD107a mAb staining. (B-C) S2 cells were preincubated with serial dilutions of a rabbit anti-S2 serum. The percentage of ΔCD107a⁺ NK cells from 1 representative experiment is shown. Experiments are representative of 3 independent experiments.