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Anti-CD3-induced cell death in T cell hybridomas: mitochondrial failure and DNA fragmentation are distinct events
1ICRF, Department of Biology, University College London, GB.
Abstract:
Triggering of the T cell receptor of T cell hybridomas leads to interleukin (IL) 2 secretion, inhibition of spontaneous growth, degradation of genomic DNA and cell death. We have investigated the relationship between the ability of mitochondria to convert 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), DNA fragmentation and growth arrest in hybridomas stimulated with anti-CD3/T cell receptor antibodies. We describe a variant T hybridoma whose mitochondrial function remains unaffected upon stimulation with anti-CD3 antibody, although it does undergo DNA fragmentation. By contrast, treatment of another anti-CD3-stimulated T hybridoma with endonuclease inhibitor completely inhibits the DNA fragmentation response but not mitochondrial failure induced by anti-CD3 antibody. Thus, we have been able to dissociate anti-CD3-induced mitochondrial failure and DNA fragmentation, suggesting that they are separate events. Although both undoubtedly contribute to cell death induced by activation the primary cause of death may be mitochondrial failure rather than DNA fragmentation.
Insights
T cell activation triggers interleukin-2 secretion and cell death. This study found that mitochondrial failure, not DNA fragmentation, is the primary cause of cell death in T cell hybridomas stimulated with anti-CD3 antibodies.
Area of Science:
- Immunology
- Cell Biology
- Molecular Biology
Background:
- T cell receptor (TCR) triggering in T cell hybridomas induces interleukin-2 (IL-2) secretion, growth inhibition, DNA fragmentation, and cell death.
- The interplay between mitochondrial function, DNA fragmentation, and cell death following TCR stimulation requires further elucidation.
Purpose of the Study:
- To investigate the relationship between mitochondrial metabolic activity (MTT conversion), DNA fragmentation, and growth arrest in T cell hybridomas stimulated with anti-CD3/TCR antibodies.
- To determine whether mitochondrial failure or DNA fragmentation is the primary driver of cell death upon TCR activation.
Main Methods:
- Utilized T cell hybridoma models to study responses to anti-CD3 antibody stimulation.
- Assessed mitochondrial function via MTT conversion assay.
- Monitored DNA fragmentation as an indicator of apoptosis.
- Employed endonuclease inhibitors to dissect the role of DNA fragmentation.
Main Results:
- A variant T hybridoma exhibited DNA fragmentation but maintained mitochondrial function after anti-CD3 stimulation.
- In another T hybridoma, endonuclease inhibition blocked DNA fragmentation but not anti-CD3-induced mitochondrial failure.
- These findings dissociate mitochondrial failure and DNA fragmentation as independent events in anti-CD3-mediated cell death.
Conclusions:
- Anti-CD3-induced mitochondrial failure and DNA fragmentation are distinct processes.
- Mitochondrial failure, rather than DNA fragmentation, is likely the primary cause of cell death in activated T cell hybridomas.