Gene expression by Treg subsets

Thymic-derived natural T regulatory cells (nTregs) are characterized by functional and phenotypic heterogeneity. Recently, a small fraction of peripheral Tregs have been shown to express Klrg1, but it remains unclear the extent Klrg1 defines a unique Treg subset. Here we show that Klrg1+ Tregs represent a terminally differentiated Treg subset derived from Klrg1- Tregs. This subset is a recent antigen-responsive and a highly activated short-lived Treg population that expresses enhanced levels of Treg suppressive molecules and that preferentially resides within mucosal tissues. The development of Klrg1+ Tregs also requires extensive IL-2R signaling. This activity represents a distinct function for IL-2, independent from its contribution to Treg homeostasis and competitive fitness. These and other properties are analogous to terminally differentiated short-lived CD8+ T effector cells. Our findings suggest that an important pathway driving antigen-activated conventional T lymphocytes also operates for Tregs. Gene expression analysis was performed of this and other Treg subsets based on expression of CD62L, CD69, and Klrg1 to define the molecular properties of Klrg1+ Tregs and its relationship to other Treg subsets found in the peripheral immune tissues. Mice were euthanized, spleen cell preparations were made, and each Treg subset was isolated by FACS cell sorting. RNA was immediately prepared for processing.