Analysis of the DNAM-1–induced cytolytic activity in IL-2–activated LAD1 NK cells. (A) IL-2–activated NK cell populations derived from LAD1 patient 1 and from 2 representative age-matched healthy donors were analyzed for cytolytic activity against BW5147 murine cell line either untransfected or transfected with the PVR molecule (BW5147/PVR⁺) at different E/T ratios. (B) IL-2–activated NK cell populations from LAD1 patients and from representative age-matched healthy donors were analyzed for cytolytic activity against BW5147 cell line untransfected (white bar) or PVR transfected (black bars) either in the absence of mAb or in the presence of mAbs specific for the indicated molecules. The E/T ratios used were 20:1 for LAD1 NK cell populations, 5:1 for healthy donor 1, 10:1 for healthy donor 2, and 5:1 for healthy donor 3. The results are representative of 3 independent experiments; the standard deviation of the mean of the triplicates was less than 5%.