Table 2.

Properties and functions of ion channels and transporters in T cells.

Channel			Ion		Function	Channelopathy
Ca2+
CRAC
Orai 1			Ca2+		Involved with T cell activation, proliferation, cytokine production 7, 14, 15	Mutations in STIM1, ORAI, 69 Leads to combined immunodeficiency 68, autoimmunity 70, 71
Orai 2
Orai 3
TRP
TRP			Ca2+, Na+		Enhances TCR signalling Regulates Th1/Th2 differentiation, 26
TRPM2			Ca2+, Na+		Activation and cytokine production
TRPM4			Na+		Cytokine production 29
TRPM7			Ni2+,Zn2+, Mg2+>Ca2+		Thymocyte development, production of thymic growth factors 7
P2X
P2X7			Ca2+, Na+ other		Involved with T-cell proliferation, cytokine production,	SLE 23, 72, 73
					Promotes Th17, Inhibits Treg differentiation 19
P2X1,4			Ca2+, Na+		T-cell proliferation, Cytokine production, Thymocyte apoptosis
Cav
Cav, 1.2, 1.3, 1.4			Ca2+,		Cytokine production, CD8 T-cell survival, CD8 T-cell immunity to infection, Th2 function in asthma
					Secretion of IL-2.
K+
Kv1.3			K+		Regulation of Vm , T-cell activation (Th17, TEM) Cytokine production,	Multiple sclerosis 74, 75 Congestive cardiac failure 76 Autoimmunity and inflammation 70
KCa3.1			K+		Hyperpolarisation of Vm, T-cell activation (Th1, Th2, TCM), cytokine production, autoimmune colitis	Cancer 77–79
Chloride
Clswell			Cl- (I-, Br-)		Apoptosis in T-cells	Agammaglobulinemia 80
CFTR			Cl-		Cytokine production
GABAA			Cl-		Inhibition of T-cell proliferation, cytokine production, cytotoxicity, and T-cell mediated autoimmunity
Magnesium
MagT1			Mg2+		CD4+ development and activation. Immunity to infection (EBV) 49	XMEN syndrome caused by X-linked mutations in MAGT1 33
Zinc
ZIP3, ZIP6, ZIP8					T-cell activation, T-cell development 7	Acrodermatitis enteropathica with immune deficiency caused by mutations in intestinal ZIP4 transporter
Other
Nicotinic Acetylcholine Receptor			Allows entry of cations		Stabilises open and desensitised state of channel
Glutamate receptor eg NMDA			Na+, Ca2+
Acid sensing ion channel			H+ Transports H2O and glycerol in some cases		Regulates fluid balance, osmotic potential

Cav, voltage-gated Ca²⁺ channel; CFTR, Cystic fibrosis transmembrane conductance regulator; CRAC, Ca²⁺ release activated Ca²⁺ channel; GABA, γ-aminobutyric acid; Kv, voltage-gated K⁺ channel; KCa, Ca²⁺ gated K⁺ channel; MagT, Mg²⁺ transporter; STIM, stromal interaction molecule; TRP, transient receptor potential; Vm, membrane potential; XMEN, X-linked immunodeficiency with Mg²⁺ defect and EBV infection and neoplasia; ZIP, Zrt-Irt like protein; ZnT, Zinc transporter.