Regulatory T (T
) cells protect the brain after stroke. Experiments by Liesz et al.  show that Treg cells prevent delayed lesion expansion in an IL-10-dependent manner in a mouse model of acute ischemic stroke. They also reduce the proinflammatory cytokine levels during the early postischemic inflammatory phase. Injection of IL-10 in the brain reduces infarct volume. Reprinted by permission from Macmillan Publishers Ltd: Nature Medicine 15, 138-139 Copyright 2009.