DLE-HuM195 improves ADCC and serial killing by unactivated NK cells ex vivo and increases CD16-mediated signaling. The 6-hour single-cell endpoint assay was used to determine (A) the overall frequencies of NK cell-mediated ADCC (at least 2810 events were analyzed for each donor and mAb condition tested), and (B) overall serial killing frequencies (ability to kill at least 2 targets) of NK cells (E:T ratio, 1:2-3) (an average of at least 120 events were analyzed for each donor and mAb condition tested). Donut plots summarizing the frequency of killing outcomes of the interactions between single NK cells and the indicated number of target cells are also shown. Values displayed are background-corrected; bars represent mean ± SD. (C) Normalized ZAP-70 phosphorylation in single NK cells as measured by phospho-flow and expressed as baseline-corrected percentage of maximum, the latter being obtained by cross-linking of CD16. The values are presented as mean ± SD derived from 4 separate donors. Stars represent P values for each panel and were calculated as described in supplemental Table 1 (P₃₄-P₃₇).