Assessment of NK cell cytotoxicity induced by IL-15 based immunotherapy against cancer cells.

Natural Killer (NK) cells are at the interface of the innate and adaptive immune system. While they are naturally able to kill pathogen-infected, malignant and compromised cells, they also drive the recruitment and activation of other immune cells through the production of inflammatory cytokines and chemokines. Evaluation of NK cells cytotoxic activity is critical to determine accurately the anti-tumor potency of novel immunotherapies, in particular, when the later aim to overcome NK cells exhaustion driven by an immunosuppressive environment such as the tumor microenvironment. Here, we provide a detailed protocol for the assessment of primary NK cells cytotoxic functions against pancreatic cancer cells stimulated by a directed approach on NK cells based on the cytokine IL-15. This article describes the protocol of a flow cytometry-based assay and a calcein acetoxymethyl ester (AM) cell viability assay to quantify NK cell cytotoxic activity. Both methods are robust, fast and sensitive to be applicable in clinics and can readily be adapted for the assessment of other immunotherapies on NK cells cytotoxicity.