Tregs and kidney: From diabetic nephropathy to renal transplantation

Table 1 Regulatory cells in humans

Cell	Phenotype	Properties	Ref.
T-cells (Treg)	CD4+CD25+	Secrete mainly IL-10 and TGF-β; some secrete IL-35 or IFN-γ	[1-4,17,77-79]
	CD4+CD25+FoxP3+
	CD4+CD25+CD127-/low
	CD4+CD45RO+
	CD8+	Secrete mainly IL-10 but also TGF-β, IFN-γ, CCL4; downregulate APC or DC maturation; direct killing of CD4+ Teffs and APCs	[80]
	CD28+
	CD8+CD28-(FoxP3+)
	CTLA-4	Mainly inhibition of Teffs	[81]
	CD4-CD8-TCRαβ+	Suppress antigen-specific T-cells; secrete mainly IFN-γ but also IL-4	[82]
	TCRγδ+	Secrete IL-10, TGF-β, IL-4	[83]
T-cells or monocytes	HLA-G	Secrete IL-10, IL-35, TGF-β, soluble HLA-G	[84,85]
iNKT	CD3+CD16+CD56+	Can secrete IFN-γ± IL-4 ± IL-10 ± TGF-γ, direct killing of target cells	[86]
B-cells (Breg)	CD19/20+, CD80/86+, CD40+, TLR4+, mainly IgG and IgA BCR	Secrete IL-10 and IL-35, induce Tregs, downregulate DC maturation	[87]
tDC	PD-L1/L2+, FasL+	Secrete IL-10 and TGF-β; downregulate Teff activation	[88]

APC: Antigen presenting cell; DC: Dendritic cell; BCR: B-cell receptor; tDC: Tolerogenic dendritic cells; iNKT: Natural killer T regulatory cells; TGF: Transforming growth factor; IL: Interleukin; IFN: Interferon; HLA-G: Human leukocyte antigen-G; CTLA-4: Cytotoxic T lymphocyte-associated antigen 4.