TNF-α secretion, IFN-γ secretion, and cytotoxicity induced by pair-wise combinations of NK-cell receptors. TNF-α (A) and IFN-γ (B) secretion by resting NK cells after 2 or 6 hours of stimulation, respectively, with beads coated with specific combinations of mAbs, as indicated. (C) Redirected lysis of P815 cells by resting NK cells at an E/T cell ratio of 10, for 3 hours at 37°C. P815 target cells were preincubated with combinations of mAbs to specific NK-cell receptors, as indicated.