Table 1.

Treg cells subtypes.

			Characterize by	Localization	Function
Ontogeny	tTreg cells		CD45RA+ FOXP3lo Helioshi Nrp1 hi	Thymus	tTreg cell TCR repertoire recognizes self-antigens
	pTreg cells		CD45RA- FOXP3hi Helioslo/- Nrp1 lo/-	Secondary lymphoid organs	pTreg cell TCR repertoire recognizes tissue specific and foreign antigens
Function	cTreg cells		CD45RA+ FOXP3lo CD25lo CD62Lhi CD44lo CCR7hi, secondary lymphoid tissue homing molecule	Leave the thymus to lymphoid tissues, enriched in secondary lymphoid organs	Naïve phenotype with low suppressive activity Control autoimmune reactions and induce transplant tolerance
	eTreg cells		CD45RA- FOXP3hi CD25hi CD62Llo CD44hi CCR7lo Activation molecules: ICOS and OX-40 Inhibitory molecules: CTLA, PD-1, TIGIT and LAG-3 Effector molecules: IL-10, TGF-β, IL-35	Originated in secondary lymphoid organs and migrate to non-lymphoid tissues	Highly suppressive cells Maintain immune homeostasis OX-40+ and ICOS+ Treg cell: secrete high levels of suppressive cytokines such as IL-10 CTLA+, PD-1 and TIGIT+ Treg cell: impair dendritic cell function preventing Teff activation
	eTreg cell subtypes	Th1-like Treg cells	T-bet+ IFNγ+ CXCR3, migration to inflamed tissue mediated by Th1 cells	Inflammatory loci in non-lymphoid tissues	Inflammatory autoimmunity Secrete IFNγ and suppress Th1 and Th17 pro-inflammatory immune response
		Th2-like Treg cells	Gata3+ IRF4+ IL4+ CCR8, recruitment to inflamed tissue mediated by Th2 cells	Inflammatory loci in non-lymphoid tissues	Secrete IL-4 and IL-13 and suppress Th2- mediated response
		Th17-like Treg cells	RORγt+ IL-17+ CCR6, recruitment to inflamed tissue mediated by Th17 cells	Inflammatory loci in non-lymphoid tissues	Oral tolerance Mucosal immunity, maintain homeostasis and tolerance to commensal microbiota Secrete anti-inflammatory IL-10 to inhibit pathogenic Th17 cell responses