Retinoic acid hypersensitivity promotes peripheral tolerance in recent thymic emigrants.

Whereas thymic education eliminates most self-reactive T cells, additional mechanisms to promote tolerance in the periphery are critical to prevent excessive immune responses against benign environmental Ags and some self-Ags. In this study we show that murine CD4(+) recent thymic emigrants (RTEs) are programmed to facilitate tolerance in the periphery. Both in vitro and in vivo, naive RTEs more readily upregulate Foxp3 than do mature naive cells after stimulation under tolerogenic conditions.