Related Experiment Video
Updated: Dec 6, 2025
A Flow Cytometry-Based Cytotoxicity Assay for the Assessment of Human NK Cell Activity
Published on: August 9, 2017
Droplet-Based Cytotoxicity Assay: Implementation of Time-Efficient Screening of Antitumor Activity of Natural Killer
Silvia Antona1,2, Ilia Platzman1,2, Joachim P Spatz1,2,3
1Department of Cellular Biophysics, Max Planck Institute for Medical Research, Jahnstraße 29, 69120 Heidelberg, Germany.
Abstract:
Natural killer (NK) cells are key players of the innate immune system. Due to their rapid cytotoxicity against infectious pathogens, hematologic malignancies, and solid tumors, NK cells represent solid candidates for cell-based immunotherapy. Despite the progress made in recent years, the heterogeneity in their cytotoxic behavior represents a drawback. With the goal of screening the intrinsic diversity of NK cells, droplet-based microfluidic technology is exploited to develop a single-cell time-efficient cytotoxicity assay. Toward this end, NK-92 cells are coencapsulated with hematological tumor cell lines in water-in-oil droplets of different sizes and their cytotoxic activity is evaluated. The effect of droplet-based confinement on NK cytotoxicity is investigated by controlling the droplet volume. The successful optimization of the droplet size allows for time efficiency compared to cytotoxicity assays based on flow cytometry. Additionally, the ability of individual NK-92 cells to kill multiple target cells in series is explored, expanding the knowledge about the serial killing process dynamics. The developed droplet-based microfluidic assay does not require the labeling of NK cells and represents a step toward developing of a forthcoming process for the selection of NK cells with the highest cytotoxicity against specific targets.
Insights
This study developed a microfluidic assay to efficiently screen natural killer (NK) cell diversity and cytotoxicity. The new method enables faster evaluation of NK cell killing capabilities for immunotherapy applications.
Area of Science:
- Immunology
- Biotechnology
- Microfluidics
Background:
- Natural killer (NK) cells are crucial for innate immunity and cancer immunotherapy.
- NK cell heterogeneity in cytotoxic activity poses a challenge for therapeutic development.
- Existing cytotoxicity assays lack efficiency in screening NK cell diversity.
Purpose of the Study:
- To develop a droplet-based microfluidic assay for high-throughput, single-cell analysis of NK cell cytotoxicity.
- To investigate the impact of droplet confinement on NK cell killing efficiency.
- To explore the serial killing capacity of individual NK cells.
Main Methods:
- Co-encapsulation of NK-92 cells and hematological tumor cell lines within water-in-oil droplets.
- Utilizing droplet-based microfluidics to control droplet volume and assess NK cell cytotoxicity.
- Evaluating NK cell activity without the need for cell labeling.
Main Results:
- Optimized droplet size enabled time-efficient cytotoxicity assessment compared to flow cytometry.
- Demonstrated the ability of individual NK cells to perform serial killing of multiple target cells.
- The assay successfully screened intrinsic NK cell diversity and cytotoxic behavior.
Conclusions:
- The developed microfluidic assay offers a time-efficient and label-free method for evaluating NK cell cytotoxicity.
- This technology advances the understanding of NK cell heterogeneity and serial killing dynamics.
- It paves the way for selecting NK cells with enhanced cytotoxic potential for immunotherapy.
