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Updated: Aug 13, 2026
Cell-based Flow Cytometry Assay to Measure Cytotoxic Activity
Published on: December 17, 2013
Gammadelta T-lymphocyte cytotoxic activity against Mycobacterium bovis analyzed by flow cytometry
Michael R Olin1, K Hwa Choi, Jinhee Lee
1Clinical and Population Sciences, College of Veterinary Medicine, University of Minnesota, St. Paul, MN 55108, USA.
Insights
Gamma Delta T lymphocytes show enhanced natural killer activity after Mycobacterium bovis BCG vaccination. A new flow cytometry assay reliably measures this cytolytic activity against mycobacteria.
Area of Science:
- Immunology
- Cellular Biology
Background:
- Gamma Delta (gammadelta) T lymphocytes bridge innate and adaptive immunity.
- They possess natural killer (NK) receptors for cytolytic functions.
- Previous studies show gammadelta T cells respond to Mycobacterium tuberculosis.
Purpose of the Study:
- Assess gammadelta T lymphocyte NK activity post-BCG vaccination using flow cytometry.
- Optimize the assay for antigen-specific mycobacterial activity.
- Compare gammadelta and CD-8 T cell cytolytic activity.
Main Methods:
- Utilized a novel flow cytometry-based cytolytic assay without radioactive materials.
- Applied the assay to assess gammadelta T cell NK activity in BCG-vaccinated animals.
- Incubated cells with M. bovis-infected monocytes to evaluate antigen-specific responses.
Main Results:
- BCG vaccination significantly increased gammadelta T lymphocyte NK activity (P=0.012).
- Innate and antigen-specific cytolytic activity increased after incubation with M. bovis-infected monocytes (P=0.02, P=0.04).
Conclusions:
- The flow cytometry assay is a sensitive and reliable tool for assessing gammadelta T lymphocyte cytolytic activity.
- This assay can be used to evaluate responses against mycobacteria.
- Findings highlight gammadelta T cells' role in immune responses to mycobacterial infections.
Abstract:
Gamma Delta (gammadelta) T lymphocytes contain the unique capability of responding to pathogens in both an innate and acquired immune response. Previously, gammadelta lymphocytes have been reported to respond to Mycobacteria tuberculosis determined by proliferation and IFN-gamma production. Unlike alpha beta (alphabeta) lymphocytes, gammadelta lymphocytes constitutively express a natural killer receptor providing gammadelta lymphocytes the capability for innate cytolytic functions. A new cytolytic assay by flow cytometry was reported capable of determining natural killer activity using K562 cells as targets without the need for radioactive materials. The objectives of this study were to first apply the flow cytometer-based assay to assess gammadelta lymphocytes natural killer activity following animal vaccination with Mycobacterium bovis Bacillus Calmette-Guerin (BCG). Secondly, to optimize the flow cytometer assay in order to detect antigen specific cytolytic activity to mycobacterium and to compare the cytolytic activity of gammadelta lymphocytes to CD-8 lymphocytes. gammadelta lymphocytes increased in NK activity (P=0.012) following animal vaccination with M. bovis BCG. Both innate (P=0.02) and acquired antigen-specific cytolytic activity (P=0.04) increased following incubation with M. bovis-infected monocytes. In conclusion, flow cytometric-based assay is a sensitive and reliable tool to determine cytolytic activity of gammadelta T-lymphocytes against mycobacterium.
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