# Tregs (T regulatory cells)

T regulatory cells (Tregs) are a specialized subset of CD4+ T cells, defined by a master protein called FOXP3. Their job is to suppress excessive immune responses and keep your immune system from attacking your own body (self-tolerance). They do this several ways. They secrete calming cytokines (IL-10 and TGF-β). They soak up the growth signal IL-2 (via high-affinity CD25). They carry inhibitory receptors like CTLA-4. And they can directly kill activated effector cells. With age, Treg numbers in your blood usually stay steady or rise, but their suppressive function may weaken. There is a paradox here. High Treg activity can hurt by dampening anti-tumor immunity, yet in some tissues it helps by limiting chronic inflammation. In the tumor environment, heavy Treg infiltration goes with immune evasion and a worse prognosis.

## Sources

- Sakaguchi S, Sakaguchi N, Asano M, Itoh M, Toda M. (1995). Immunologic Self-Tolerance Maintained by Activated T Cells Expressing IL-2 Receptor Alpha-Chains (CD25). Journal of Immunology. https://doi.org/10.4049/jimmunol.155.3.1151
- Deng G, Song X, Greene MI. (2021). FOXP3+ Regulatory T Cells and Age-Related Diseases. FEBS Journal. https://doi.org/10.1111/febs.15743

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_Canonical: https://longevity-switzerland.com/en/glossary/tregs · Part of Longevity Cities · Updated 2026-06-22_