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Regulating T helper cell immunity through antigen responsiveness and calcium entry.
G Bikah1, R R Pogue-Caley, L J McHeyzer-Williams
1Department of Immunology, Duke University Medical Center, Durham, NC 27710, USA.
Nature Immunology
|March 23, 2001
Summary
During an immune response, antigen-specific T helper (TH) cells show reduced signaling and proliferation. Cross-linking CD69 protein can restore TH cell function by improving calcium entry and proliferation.
Area of Science:
- Immunology
- Cellular Biology
- Molecular Signaling
Background:
- T helper (TH) cells are crucial for adaptive immunity.
- Their function is tightly regulated during immune responses.
- Understanding TH cell regulation is key to developing immunotherapies.
Purpose of the Study:
- To investigate changes in signaling and proliferation of antigen-specific TH cells during a primary immune response.
- To identify mechanisms regulating TH cell responsiveness in vivo.
Main Methods:
- Single-cell analysis of T helper cells during a primary immune response.
- Measurement of intracellular calcium mobilization (capacitative calcium entry - CCE).
- Assessment of proliferative capacity in response to T cell receptor (TCR) stimulation and cytokines.
Main Results:
- Antigen-specific TH cells exhibited impaired calcium signaling and proliferation at the peak of cellular expansion.
- A block in CD3/CD4-mediated calcium mobilization and capacitative calcium entry (CCE) was observed.
- Cross-linking CD69 on a subset of TH cells restored CCE and proliferative capacity.
- CD69-mediated rescue involved G protein signaling, calmodulin, and calcineurin.
Conclusions:
- Antigen-specific TH cells undergo significant changes in responsiveness during an immune response.
- CD69 plays a critical role in regulating TH cell signaling and proliferation.
- These findings reveal novel mechanisms for controlling T helper cell development and function.