Expansion of Natural Killer Cells

Sintilimab (Tyvyt) is a monoclonal antibody against programmed cell death protein 1 (PD-1). It could block the interaction between PD-1 and its ligands and help the anti-tumor effect of T-cells to recover. Sintilimab is developed by Innovent Biologics and Eli Lilly and Company (18 (link)). NK cells were expanded by our previously described method (19 (link)). Briefly, blood samples were centrifuged at 1800×g for 10 min, and plasma was transferred to new tubes. Peripheral blood mononuclear cells (PBMCs) were isolated by density gradient centrifugation using Ficoll (Axis-Shield PoC AS, Oslo, Norway) at 800×g for 30 min. PBMCs were resuspended in Aly505 medium (Cell Science & Technology Institute Inc., Yamagata, Japan) medium with 5% auto-plasma, 600 U/mL IL-2, and 10 ng/mL IL-15 (both from Miltenyi Biotec, Germany) and 1 μg/mL OK432 (T&L Biological Technology, Beijing, China) at a concentration of 1×10⁶ cells/mL in a humidified atmosphere of 5% CO₂. The cells were cultured in Aly505 medium supplemented with 5% auto-plasma, 500 U/mL IL-2 and 10 ng/mL IL-15 at 37°C for the following days.