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.

Last reviewed: June 22, 2026

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