Table 1.

Expression, ligands and signaling pathways of immune checkpoint molecules (based on [210] and [211])

Immune checkpoint receptors (synonym)	Cellular expression	Ligand	Intracellular motif	Signaling pathways
CTLA-4 (CD152)	T cells	CD80, CD86	YxxM	SHP2, LCK/ZAP70/PI3K PP2A/AKT
PD-1 (CD279)	T cells, B cells, DCs, NKT cells, Monocytes	PD-L1, PD-L2	ITIM, ITSM	SHP1, PI3K/AKT SHP2, LCK/ZAP70/PI3K, RAS
TIGIT (VSIG9, VSTM3)	T cells, NK and NKT cells	CD155, CD112	2 × ITIM	NF-kB, PI3K and MAPK
LAG-3 (CD223)	T cells, B cells, DC, NK cells	MHCII	KIEELE	not determined
2B4 (CD244)	T cells, NK cells, Monocytes, Basophiles	CD2, CD48	ITSM	not determined
BTLA (CD272)	T cells, B cells, DC, Macrophages, Myeloid cells	HVEM, CD80	ITIM, ITSM	SHP1, PI3K/AKT SHP2, LCK/ZAP70/PI3K
TIM3 (HAVCR2)	T cells, B cells, NK cells, NKT cells, DCs, Macrophages	Gal-9	Y235, Y242	PI3K BAT3/LCK
VISTA (PD1-H)	T cells, DCs, Macrophages, Monocytes, Neutrophils	not determined	not determined	not determined
CD96 (Tactile)	T cells, NK cells, Myeloid cells	CD155	ITIM	not determined