TCR Signaling and CD28/CTLA-4 Signaling Cooperatively Modulate T Regulatory Cell Homeostasis

Foxp3+ T regulatory cells (Tregs), conventional CD4+Foxp3− T cells, and CD8+ T cells represent heterogeneous populations composed of naive phenotype (NP, CD44low) and memory phenotype (MP, CD44high) subpopulations. NP and MP subsets differ in their activation state, contribution to immune function, and capacity to proliferate in vivo. To further understand the factors that contribute to the differential homeostasis of NP/MP subsets, we examined...