. 2021 Dec 15;2(3):147–156. doi: 10.2478/rir-2021-0021

Table 2.

CD4⁺ T_regs markers and mechanisms of action.

Subset	Natural/induced	Markers	Mechanisms of Action	Ref.
CD4⁺ T_regs (mice, humans)	Induced/natural	CD4, CD25, FoxP3, IL-10, IL-35, GITR, CD127^low	Suppress T effector cells, cell-to-cell contact, downregulation of CD80/CD86, metabolic disruption	[18, 40, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75]
CD4⁺ T_regs (humans)	Natural	CD4, CD25, GARP, CD45RA/RO, CCR6 Helios, CD127^low	Suppress T effector cells	[35, 40, 46, 47, 63, 76, 77, 78]
Tr1	Natural	CD4, CD25, IL-10, IL-35	Suppress T effector cells, induction of B7-H4 on APCs through IL-10, TGF-β, IL-35	[40, 46, 47, 79]
Th1, Th2, Th3	Natural	CD4, CD25, CXCR CXCR3⁺ T cells that can produce IFN-γ, IL-4	Suppress T effector cells through IL-10, TGF-β, IFN-γ, IL-4	[63, 64, 65, 66, 67]
IL-17⁺ FoxP3⁺ T_regs (mice, humans)	Natural	CD4, FOXP3, CCR6, RORγt	Suppress CD4⁺ T cell proliferation	[40, 46, 47]
CD45RA⁺ FoxP3^low T_regs (mice, humans)	Natural	CD4, CD45RA, FOXP3	Resting T_regs	[40, 46, 47]
Follicular T_regs (mice)	Natural	CD4, Foxp3, CXCR5, Bcl6	Germinal centers	[40, 46, 47]
CD4⁺CD25^low/−GITR⁺ (humans)	Natural	CD4⁺ CD25^low/−GITR⁺	Suppress T effector cells	[48]
CD4⁺CD25⁺ CXCR2⁺FoxP3⁺ CD45RO⁺ (humans)	Natural/induced	CD4⁺CD25⁺ CXCR2⁺FoxP3⁺ CD45RO⁺	Suppress T effector cells	[51]
CD4⁺CD161⁺ FoxP3⁺ (humans)	Natural	CD127^low, IL-2, IFNγ, IL-17	Suppress T effector cells	[57, 58]
CD4⁺CXCR5⁺ FoxP3⁺ (mice, humans)	Natural	CD4⁺CXCR5⁺	Suppress B-cell antibody production	[59]
Follicular CD4⁺Bcl6⁻FoxP3⁺ T_regs (mice, humans)	Natural	CD4⁺Bcl6⁻FoxP3⁺	Suppress germinal center reactions	[60]

APC, antigen presenting cells; T_regs, T regulatory cells; Tr1, type-1 regulatory.