A single large population of healer cells, called regulatory T cells, is whizzing around our body - not multiple specialist populations restricted to specific parts of the body as previously thought. These cells shut down inflammation and repair the collateral damage to cells caused after our immune system has responded to injury or illness. Tests, in mice, of a drug developed by the researchers showed that regulatory T cells can be attracted to specific body parts, boosted in number, and activated to suppress immune response and rebuild tissue. Current anti-inflammatory drugs used for this purpose suppress the body’s whole immune system, making patients more vulnerable to infection. The discovery could lead to more targeted treatments, with fewer side-effects, for issues from lengthy COVID infections to autoimmune diseases like multiple sclerosis. Clinical trials in humans are now planned.