Cytotoxic Dynamics of Natural Killer Cell at the Single Cell Level

Natural Killer (NK) cell, a crucial player of the human immune defense system, detects and kills virus-infected cells and cancer cells. Although the relevant molecular machineries involved in NK cell activation and NK-target cell interactions are largely known, how their collected dynamics regulate fast yet highly selective target cell killing in the complex environment of tissues is poorly understood. In traditional bulk killing assays, heterogeneity and kinetic details of individual NK-target cell interactions are masked, seriously limiting analysis of the underlying dynamic mechanism(s). Therefore, in this proposed study we will develop quantitative single-cell microscopy assays in chemically and physically defined environments using microfluidic platform, to investigate the real-time killing dynamics of epithelial cancer cells by primary NK cells purified from human blood. Our goal is to determine rate-limiting steps in NK-cancer cell interaction, identify mechanistically relevant heterogeneity in the process, and relate the observed kinetics and heterogeneity to key molecular events and regulatory components of the NK cell machinery in a quantitative manner. The interdisciplinary approach that we employ will integrate complementary experimental and theoretical methodologies in live-cell imaging, microfluidics engineering, systemic profiling and computational modeling. The resulting fundamental knowledge will significantly improve our understanding of the cytotoxic mechanism of primary NK cell, in particular regarding how NK cell killing varies between different cancer targets. NK cells are considered promising candidate for cancer treatment, especially for eliminating residual cancer cells after conventional therapy. Results from our proposed study will provide new mechanistic insight to develop this treatment strategy. The integrative platform that we develop will also be readily extendable to analysis of other cell-cell interaction dynamics, e.g. in macrophage and T cell function.