Flow Cytometry Analysis of NK Cell Phenotype and Function in Aging

Natural killer (NK) cells represent a subpopulation of lymphocytes involved in innate immunity, defined recently as group 1 of innate lymphoid cells (ILCs). NK cells are cytotoxic lymphocytes with a relevant role in the destruction of transformed cells as virus-infected or tumor cells, as well as the regulation of the immune response through cytokine and chemokine production that activates other cellular components of innate and adaptive immunity. In humans, NK cell subsets have been defined according to the level of expression of CD56. Aging differentially affects NK cell subsets and NK cell function. Here, we describe protocols for the delineation of NK cell subsets and the analysis of their functional capacity using multiparametric flow cytometry.