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Updated: Aug 25, 2026
Flow Cytometry-based Assay for the Monitoring of NK Cell Functions
Published on: October 30, 2016
Assessment of Natural Killer Cell Serial Degranulation
Jens A Niemann1, Carsten Watzl1
1Department of Immunology, Leibniz Research Centre for Working Environment and Human Factors (IfADo), Dortmund, Germany.
Abstract:
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.
Insights
This study details a new method to identify "serial killer" natural killer (NK) cells. These cells can eliminate multiple targets by releasing cytotoxic granules, a process detectable by tracking CD107a expression.
Area of Science:
- Immunology
- Cell Biology
- Cytometry
Background:
- Natural killer (NK) cells exhibit functional heterogeneity.
- Some NK cells, termed serial killers, can eliminate multiple target cells sequentially.
- Serial killing activity is primarily mediated by the release of cytotoxic granules.
Purpose of the Study:
- To describe a novel protocol for the detection and characterization of serial degranulating human NK cells.
- To enable the analysis of NK cell serial degranulation capacity in co-culture systems.
Main Methods:
- A protocol for the sequential staining of extracellular CD107a on NK cells is presented.
- This method allows for the analysis of NK cell degranulation events over time.
- The assay is performed in co-culture with target cells.
Main Results:
- The protocol enables the identification and characterization of human NK cells with serial degranulation capabilities.
- Quantification of serial degranulation provides insights into NK cell cytotoxic potential.
- CD107a surface exposure serves as a marker for granule release during serial killing.
Conclusions:
- The described protocol offers a robust method for studying NK cell serial cytotoxicity.
- Understanding serial killer NK cell function is crucial for immunology research.
- This assay facilitates the characterization of NK cell heterogeneity and effector functions.
