Millipore FlowCellect™ Human NK Cell Characterization Kit

Background Information

Natural Killer (NK) cells are a subset of lymphocytes that serve in innate immunity. These cells are defined phenotypically by the presence of surface neural cell adhesion molecule (NCAM) or CD56, and the absence of the T-cell coreceptor CD3, with a large percentage of these cells also expressing the Fc gamma receptor molecule or CD16. Natural Killer cells are larger in size than their B and T-lymphocyte counterparts.

The activation of NK cells is a two-signal mechanism, consisting of the interplay between a positive and negative signal. The positive signal takes the form of an activation receptor which, when bound by corresponding ligands on the target cells, will trigger activity, while the presence of the major histocompatibility complex I (MHC I) molecule on the surface of the target cell serves as the negative signal. During exposure to bacterial and viral pathogens, the downregulation of surface MHC I on infected cells causes the removal of the inhibitory block on NK function, which when combined with ligation of the activation receptor, results in activation of NK effector functions.

Natural Killer cells can perform two main immune functions upon activation. The more common one is the direct lysing of target cells through the release of pro-apoptotic molecules perforin and granzyme. Meanwhile, a small subset of NK cells can also serve in an immunoregulatory role, through the secretion of various cytokines such as interferon gamma (IFN-g) to activate the function of other innate immunity cells such as macrophages.

Components