Impact of mAb 4D7 on primary human NK cell activity from healthy donors. (A) Schematic of the experimental design. Primary NK cells (5 × 10⁴) from healthy donors were cocultured with target cells (1.5 × 10⁵) for 4 hours in the presence of mAb 4D7 or matched isotype control (murine IgG1, 10 μg/mL). NK cell CD107a expression was then assessed by flow cytometry. (B) Representative CD107a degranulation percentage for donor 5. (C) Normalized mean results from 5 healthy donors. Panels show NK subsets: NKG2A^–NKG2C^– (top), NKG2A^–NKG2C⁺ (middle), and NKG2A⁺NKG2C^– (bottom). After incubation, NK cells were stained for subset markers (2 μg/mL). Data were acquired using a CytoFLEX flow cytometer and analyzed with GraphPad Prism v10. Isotype control degranulation was normalized to 1, with 4D7 mAb results adjusted accordingly. Experiments were performed in triplicate for each donor. Error bars represent ± SD. ∗P < .05; ∗∗∗∗P < .0001 (2-way ANOVA).