Dissociation of natural killer and lymphocyte-activated killer cell lytic activities in human CD3- large granular lymphocytes
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Updated: Aug 10, 2026
A Flow Cytometry-Based Cytotoxicity Assay for the Assessment of Human NK Cell Activity
Published on: August 9, 2017
M V Clément1, S Legros-Maida, A Soulie
1Hôpital Saint Louis INSERM U93, Paris, France.
Insights
Natural killer (NK) and lymphocyte-activated killer (LAK) cell activities are distinct. NK activity relies on granule exocytosis, while LAK activity requires new protein synthesis, suggesting different lytic mediators.
Area of Science:
- Immunology
- Cellular Biology
Background:
- CD3- large granular lymphocytes (LGL) exhibit natural killer (NK) cell activity.
- NK cells can acquire lymphocyte-activated killer (LAK) cell activity upon interleukin-2 exposure.
Purpose of the Study:
- To characterize the distinct lytic activities of NK and LAK cells.
- To investigate the molecular mechanisms underlying NK and LAK cell-mediated cytotoxicity.
Main Methods:
- Analysis of Ca2+ dependence of NK and LAK activities.
- Use of Ca2+ channel blockers and competitors.
- Assessment of de novo protein synthesis requirements for LAK activity.
- Investigation of granule exocytosis in NK cell-mediated lysis.
Main Results:
- Both NK and LAK activities are calcium-dependent but can be dissociated using specific agents.
- NK activity involves spontaneous granule exocytosis of lytic proteins, likely perforin.
- LAK activity requires de novo protein synthesis and is independent of granule exocytosis.
- NK and LAK activities utilize distinct lytic mediators and pathways.
Conclusions:
- NK and LAK activities represent two separate cytotoxic pathways.
- These pathways involve different molecular mechanisms and mediators, including perforin for NK cells and newly synthesized proteins for LAK cells.
Abstract:
CD3- large granular lymphocytes (LGL) are known to display natural killer cell (NK) activity without prior sensitization or restriction by major histocompatibility antigens. Upon short-term exposure to interleukin-2, NK cells were shown to acquire lymphocyte-activated killer cell (LAK) activity. The aim of this study was to analyze the characteristics of these lytic activities. Our data indicated that both NK and LAK activities were Ca2+ dependent; however, they could be dissociated by a Ca2+ channel blocker or a Ca2+ channel competitor agent. Moreover, NK activity was associated with granule exocytosis of lytic proteins spontaneously present in CD3- LGL, the most likely candidate being the pore-forming protein perforin. By contrast, LAK activity was found to be dependent on de novo protein synthesis and distinct from granule exocytosis. Our results strongly suggest that NK and LAK activities could be defined as two distinct pathways involving different lytic mediators.
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