Inhibition of cytolysis by wortmannin. Activated LD-PBL were tested for lytic activity in the presence of the PI 3-kinase inhibitor, wortmannin. CD44DL (upper panel) and ADCC (middle panel) were tested using TNP-MC1 targets in the presence of 400 (▵), 40 (□), 4 (○), 0.4 nmol/L (□), and 0 nmol/L (•) wortmannin. (▪) Lysis in the absence of antibody or wortmannin. Natural cytotoxicity (lower panel) was measured using K562 target cells in the presence of 500 (▵), 125 (□), 25 (○), and 0 nmol/L (•) wortmannin. This experiment has been repeated five times, using cells from different donors, with similar results.