Assessment of Natural Killer Cell Serial Degranulation.

Natural killer (NK) cells have been shown to be heterogeneous and to differ in their ability to kill target cells: although some NK cells show little cytotoxic activity, others sequentially kill multiple targets. The latter are called serial killers, and they perform this activity mainly via the release of cytotoxic granules. During this degranulation process, CD107a is exposed at the NK cell's surface. By staining this extracellular CD107a in a sequential manner, the ability of NK cells to serially degranulate while in co-culture with target cells can be analyzed. Here we describe a protocol for the detection and characterization of serial degranulating human NK cells. © 2026 The Author(s). Current Protocols published by Wiley Periodicals LLC. Basic Protocol: Natural killer cell serial degranulation assay.