Cutting Edge: Low-Affinity TCRs Support Regulatory T Cell Function in Autoimmunity.

Regulatory T cells (Tregs) use a distinct TCR repertoire and are more self-reactive compared with conventional T cells. However, the extent to which TCR affinity regulates the function of self-reactive Tregs is largely unknown. In this study, we used a two-TCR model to assess the role of TCR affinity in Treg function during autoimmunity. We observed that high- and low-affinity Tregs were recruited to the pancreas and contributed to protection from autoimmune diabetes. Interestingly, high-affinity cells preferentially upregulated the TCR-dependent Treg functional mediators IL-10, TIGIT, GITR, and CTLA4, whereas low-affinity cells displayed increased transcripts for Areg and Ebi3 , suggesting distinct functional profiles. The results of this study suggest mechanistically distinct and potentially nonredundant roles for high- and low-affinity Tregs in controlling autoimmunity.