Table 2.

The mechanisms by which the number or function of Treg cells is regulated.

Class	Mechanism underlying the effect	Effects on regulatory T cell	Ref.
VIP	Factors induce the inhibition of soluble protein secretion by increasing the expression of Foxp3 and TGF-β 1	Increases in the number and inhibitory activity of Treg cells changed the immune response to Th2 subsets	(100)
Anti-TNF-a	Induce Foxp3 expression	Increases in the number of circulating Treg cells	(101)
CTLA-4-Ig	Blocking T cell activation by binding to CD80/CD86 ligands	Induction of new iTreg cell populations Increase in the proportion of Treg cells Activate existing Treg cells	(102, 103)
TGF	Induction of Foxp3 expression	Induction of the differentiation of resistant Treg cells	(104)
IL-2	Activate the transcription factor STAT5	Promotes the activation and expansion of Treg cells	(105, 106)
Rapamycin	Blocking the AKT–mTOR-SMAD3 signaling axis Inducing Foxp3 expression	Inhibition of Teff cell proliferation Induction of the differentiation of Treg cells	(107)
Anti-IL-6	Rebalance the ratio of Foxp3/Ror-γt expression	Increases the Treg/Th17 ratio by suppressing Th17 generation	(108–110)
IgD-Fc-Ig	Restore the Th17/Treg cell subset balance	Reverse the imbalance of Th1/Th2 and Th17/Treg cell subsets	(111)
Anti-IL-17	Increase the Treg/Th17 ratio	Inhibition of the pro-inflammatory Th17 pathway	(112)

Ag, Antigen; iTreg, Induced Treg cell; Th, T helper cell.