Fig. 3.

N-803 stimulates IFNy production from NK cells, which upregulates PD-L1 expression on SNUC cells and increases their sensitivity to N-601-mediated NK cell lysis. A. Healthy donor NK cells were cultured in 100 ng immobilized N-803 for 24 h or left untreated as controls. ELISA was used to quantify IFNy secretion within the supernatants of each NK cell culture. B. SNUC cells from the MDA8788–6 line were then cultured for 24 h in supernatant harvested from the N-803-treated NK cells, non-treated control supernatant, or in 20 ng/mL of IFNy as a positive control. SNUC cells were analyzed by flow cytometry for percent positive cells and MFI. C. SNUC cells from part B were used as targets for NK cell-mediated lysis via ¹¹¹In-release assay. SNUC cells were treated with N-601 or isotype control antibody, and combination treatment assays were performed by treating SNUC cells with N-601 or isotype control antibody and treating NK cells with N-803. E:T ratios are 10:1. **P ≤ 0.01, ****P ≤ 0.0001.