Unlike rituximab, 161519 TriKE induces potent NK cell proliferation and survival. NK cells were enriched from fresh healthy donor samples (n = 6), CellTrace Violet labeled, and incubated for 7 days with 161519 TriKE or control treatments at 50 nM (for everything but IL-15 [used at 0.5 nM]) concentration. After the incubation period, wells were harvested, and NK cells were evaluated by flow cytometry. Pooled data (A) and representative histograms (B) showing NK cell proliferation (by CellTrace dilution) on the different treatment groups. Pooled NK cell viability (C) and representative histograms (D) showing cell death (by incorporation of Live/Dead Near IR dye) on the different treatment groups. (E) Pooled NK cell count (60 seconds at constant speed) at the time of harvest. One-way ANOVA with repeated measures was used to calculate differences against the 161519 group. Error bars indicate the mean ± standard error of the mean. Statistical significance are determined as *P < .05 and ***P < .001.