Table 1. sFGL2-expressing Tregs.

	CD4+ Tregs	CD8+ Tregs	IELs	DNTs
Immunophenotypic identification	CD4+CD25highFoxp3+	CD45RClow	CD8αα+	CD3+CD4-CD8-
Suppressive, pro-apoptotic, and cytolysis molecules	CTLA-4, LAG3, LAP, TIGIT, IL-10, TGF-β, IL-35, PD-1, CD95, GITR, galectin 1, granzymes	CTLA-4, IL-10, TGF-β, IDO, FasL, perforin	TGF-β3, LAG3, FasL, CD69, granzymes, NK-like receptors	CTLA4, FasL, perforin,
Origin	Thymus (nTreg) or periphery (iTreg)	Thymus	Intestinal epithelium	Thymus or periphery
Mechanisms	Attenuation of DC function, inhibition of Th1 and Th17 development, anti-inflammatroy apoptosis induction, Breg induction	Perforin-mediated cytolysis, FasL-induced apoptosis, induction of CD4+ Tregs, inhibitory cytokine-mediated suppression	Fas-and perforin-mediated cytotoxicity, inhibitory cytokine-mediated suppression	Perforin-mediated cytolysis, FasL-induced apoptosis, Attenuation of DC function
References	[12–14, 70, 106]	[16, 107]	[17, 108, 109]	[12, 107]

IELs, intraepithelial lymphocytes; DNTs, double negative T cells; CTLA-4, cytotoxic T lymphocyte-associated antigen 4; LAG3, lymphocyte activation gene 3; LAP, latency-associated peptide; TIGIT, T-cell Ig and ITIM domain; IL, interleukin; TGF, transforming growth factor; PD-1, programmed cell death 1; GITR, glucocorticoid-induced TNF-receptor-related protein; IDO, indoleamine 2,3-dioxygenase; FasL, Fas ligand; nTregs, natural Treg; iTreg, induced Treg.