In stroke models, beneficial effects have been shown with direct Treg cell therapy (Ito et al, 2019) (although this only works in Rag‐deficient mice), or via the use of IL33 (Liu et al, 2020) or IL2 to expand the Treg population (Zhang et al, 2018; Dong et al, 2021; Shi et al, 2021; Yshii et al, 2022b). The gene discussed is IL2; the disease is Stroke.