DLE-HuM195 increases the frequency of NK cell-mediated serial killing. (A) Overall serial killing frequencies (ability to kill at least 2 targets) of NK cells, as determined by the 6-hour endpoint single-cell assay (E:T ratio, 1:2-3) (at least 236 events were analyzed for each donor and mAb condition tested). These values represent the frequencies of serial killer NK cells as a percentage of all cytolytic NK cells incubated with 2-4 target cells. CD16-158 allotype is annotated near the donor identifying number. (B) Donut plots summarizing the average frequencies (n = 5 donors) of target killing outcomes in interactions between single NK cells and the indicated number of target cells. Stars represent significance of P values (P₂₂, P₂₃, P₂₄), calculated as detailed in supplemental Table 1. F, phenylalanine; nd, not determined; V, valine.