Evaluation of human natural killer cell activities in whole blood.

Natural killer (NK) cells are important effector cells of the innate immune system. Activation of NK cells results in their cytotoxic activity against locally attached target cells and leads to the secretion of cytokines. These activities are usually measured in purified NK cells or isolated peripheral blood mononuclear cells. In this unit, we describe a protocol to measure NK cell cytotoxicity (lysis of (51)Cr labeled target cells), degranulation (externalization of CD107a), and cytokine production (intracellular FACS analysis of IFN-γ) in whole-blood samples. Using these protocols, it is possible to perform a comprehensive analysis of NK cell function with as little as 3.5 ml of heparinized whole blood.