One reason for the relative lack of insight into CD8+ Treg function during infectious disease is because unlike CD25+ FoxP3+ CD4+ T regulatory cells, there are no universal markers for the identification of CD8+ Tregs. While a few studies have identified cell surface markers that enrich for CD8+ Treg populations from TB patient samples based on suppressive activity [50, 51], it is unclear how specific these markers are across different disease models, particularly for mouse models of infection. This evidence concerns the gene FOXP3 and infectious disease.