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Control of T cell antigen reactivity via programmed TCR downregulation
Alena M Gallegos1, Huizhong Xiong1, Ingrid M Leiner1
1Immunology Program, Sloan-Kettering Institute, Memorial Sloan-Kettering Cancer Center, New York, New York, USA.
Nature Immunology
|February 23, 2016
Summary
Activated CD4(+) T cells downregulate their T cell antigen receptor (TCR) expression after encountering antigen. This programmed response limits T cell reactivity, preventing excessive inflammation while controlling pathogens.
Area of Science:
- Immunology
- Cellular immunology
- T cell biology
Background:
- The T cell antigen receptor (TCR) exhibits variable ligand affinity, making T cell regulation challenging.
- Understanding how the immune system manages T cells with diverse reactivity is crucial.
Purpose of the Study:
- To investigate the regulation of T cell responses based on antigen recognition strength.
- To elucidate the role of T cell antigen receptor (TCR) expression levels in immune homeostasis.
Main Methods:
- Analysis of TCR expression in activated CD4(+) T cells during clonal expansion.
- Assessment of cytokine production and proliferation thresholds in relation to TCR downregulation.
- Tracking of T cell clone exclusion based on initial antigen recognition strength.
Main Results:
- Activated CD4(+) T cells downregulated TCR expression proportionally to antigen recognition strength.
- Downregulated TCR expression increased thresholds for cytokine production and recall proliferation.
- T cells with higher antigen reactivity were selectively excluded.
Conclusions:
- Programmed TCR downregulation acts as a negative feedback mechanism.
- This process constrains T cell effector function with a time delay.
- It balances pathogen control with the prevention of excessive inflammatory damage.
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