Involvement of different activating NK receptors in the lysis of ALL. In these cytolytic assays, ⁵¹Cr-labeled ALLs were used as target cells and activated polyclonal NK cell populations as effectors. ALLs were represented by LL10 (A) and LL3 (B). Saturating amounts of mAb to the indicated receptors were preincubated with NK cells. The effector-to-target cell ratio used was 20:1. Data are expressed as percentage of lysis.