. 2024 Jan 12;14:1321228. doi: 10.3389/fimmu.2023.1321228

Table 1.

Markers of human functional FOXP3⁺ Tregs.

Markers	Alternative name(s)	Marker location	Expression on resting Treg	Expression level upon activation
CD25	IL-2Rα	Surface	CD25^high	Very high
FOXP3	N/A	Intranuclear	FOXP3^high	Very high
CD127	IL-7Rα	Surface	CD127^low/-	Low/-
CD45RA	N/A	Surface	Naïve Treg are predominantly CD45RA⁺	Low/-
CD45RO	N/A	Surface	Memory Treg are predominantly CD45RO⁺	High
CD62L	L-selectin	Surface	Treg with secondary lymph node homing capacity are predominantly CD62L⁺	Retained
CCR7	CD197	Surface	Most of the Treg with secondary lymph node homing capacity are CCR7⁺	Retained
CD95	Fas	Surface	Most of the naïve Treg are CD95^low/-	High
CD44	N/A	Surface	Most of the Treg are CD44^low/-	High
CD31	PECAM-1	Surface	Recent thymic emigrant Treg are CD31⁺	Low
Helios	IKZF2	Intranuclear	Thymus derived stable Treg are Helios⁺	Stable over time
GPA33	A33	Surface	Pure and stable naïve Treg population, that are also derived from thymus, are GPA33⁺	low
CTLA-4	CD152	Surface/Intracellular	Treg express CTLA-4 constitutively at low level	High
PD-1	CD279	Surface/Intracellular	Most of the PD-1 expressing Treg retain its expression in the intracellular compartments	High (surface)
ICOS	CD278	Surface	About 20% of the peripheral Treg are ICOS⁺	High
TIGIT	VSTM3	Surface	Few Treg with activated phenotype are TIGIT⁺	High
LAG-3	CD223	Surface	Most of the resting Treg are LAG3^low/-	High
TIM-3	CD366 HAVCR2	Surface	Only 2-5% of Treg in periphery are TIM-3⁺	High
GITR	TNFRSF18 CD357	Surface	Few Treg with activated phenotype are GITR⁺	High
OX-40	CD134	Surface	Few Treg with activated phenotype are OX-40⁺	High
4-1BB	CD137	Surface	Few Treg with activated phenotype are 4-1BB⁺	High
CD27	N/A	Surface	Treg with high suppressive capacity are CD27⁺	Mostly stable over time
CD49d	α4 integrin VLA-4 α	Surface	70% of the immunosuppressive FOXP3+ Treg are CD49d^low/-	High
CD26	ADA binding protein	Surface	Most of the Treg are CD26^low/-	High
CD6	–	Surface	Most of the Treg are CD6^low/-	High
CD226	DNAM-1	Surface	Most of the Treg are CD226^low/-	High
TGF-b	TGF-b1, LAP	Surface/Intracellular	Most of the resting Treg are TGF-b^low/-	High
LAP	TGF-b1	Surface/Intracellular	Most of the resting Treg are LAP^low/-	High
GARP	LRRC32	Surface	Most of the resting Treg are GARP^low/-	High
CD39	N/A	Surface	Only effector/memory-like Treg are CD39⁺	High
CD73	N/A	Surface/Intracellular	Most of the CD73 expressing Treg retain in the intracellular compartments	High (surface)
CD121a/b	IL-1R I/II	Surface	Most of the resting Treg are CD121a/b^low/-	High (transient)
CD69	N/A	Surface	Most of the resting Treg are CD69^low/-	High
HLA-DR	N/A	Surface	Few Treg with activated phenotype are HLA-DR⁺	High
CD101	BB27	Surface	Less studied in humans	N/A
CD129	IL-9R	Surface	Less studied in humans	N/A
CD103	Integrin αEβ7	Surface	<5% Treg in various tissues, including blood are CD103⁺	N/A
Neuropilin-1	CD304	Surface	Thymic derived mouse Treg are Neuropilin-1⁺ (Human studies are controversial)	N/A
CD70	CD27L	Surface	Only 5-6% Tregs are CD70⁺	High
CD80/CD86	B7 1/2	Surface	20% Treg are CD80⁺ and <1% Treg are CD86⁺	High

References are indicated in the text.

The table above presents an overview of human Treg markers that delineate different subsets of Treg cells, along with their respective properties, as detailed in the review.