Enhancement of NK cell-mediated cytotoxicity by engagement of CD43. Effect of the proactivatory anti-CD43 TP1/36 MoAb and the control isotype-matched anti-CD56 K218 MoAb in the cytolytic activity of IL-2–cultured NK cells against P815 target cells. NK killing was determined in a 4-hour ⁵¹Cr release assay, as described in Materials and Methods. The arithmetic mean ± SE of 3 different experiments corresponding to 3 independent donors is shown. The differences were significant according to Student’st-test (P < .05).