'Nurr'ishing T reg cells: Nr4a transcription factors control Foxp3 expression

摘要

Unrestrained activation and cytokine pro- duction by T cells can result in extensive autoimmune damage to host tissue. Specialized populations of regulatory T cells (T-(reg) cells) that express the transcription factor Foxp3 provide an essential layer of defense against unwarranted T cell activation through their potent suppressor activity, which limits the proinflam-matory properties of effector T cells. T-(reg) cells can develop in the thymus as natural Tr cells or in the periphery as inducible T-(reg) cells and constitute a small proportion (-10%) of the total CD4+ T cell population. The importance of T-(reg) cells in normal homeostasis of the immune system is underscored by the fact that in humans, naturally occurring mutations that impair Foxp3 function are associated with the development of IPEX syndrome ('immune-mediated polyendocrinopathy X-linked' syndrome), in which affected male children develop multiorgan inflammation and have a limited life expectancy