T-cell regulation of peripheral tolerance and immunity: the potential rolefor Notch signalling

Recognition of antigen by T cells in the periphery may lead either to the g eneration of productive immunity or the induction of tolerance. These two f unctional outcomes are a consequence of distinct pathways of T-cell differe ntiation. T cells are selected to become regulatory cells and their functio n is to maintain homeostasis with the immune system. In this review we disc uss the cell-fate decisions that T cells might make allowing them to promot e immunity or induce tolerance in the context of the role that Notch signal ling may play in this process.