Deletion of PD-1 Destabilizes the Lineage Identity and Metabolic Fitness of Tumor-Infiltrating Regulatory T Cells

In Pdcd1fl/flFoxp3eGFP−Cre-ERT2(+/−) mice, in which both PD-1-expressing and PD-1-deficient Treg cells coexisted in the same tissue environment, conditional deletion of PD-1 in Treg cells resulted in impairment of the proliferative and suppressive capacity of TI Treg cells.