Table 1.

Signalling alterations occurring with ageing

Signalling alteration	Role in T cells
Intracellular free Ca2+	Early T-cell activation
Myo-inositol 1,4,5-trisphosphate production	Calcium release
Protein kinase C isoform translocation	T-cell activation
CD69 expression	Activation surface marker
CD71 expression	Activation surface marker
CD28 expression	Costimulatory molecule
Membrane fluidity	Protein trafficking
Cholesterol content	Lipid rafts movement
Rafts-associated proteins	Early T-cell activation, immune synapse formation
NF-AT distribution	Calcium signalling
Regulation of cellular cholesterol	Molecule sorting, lipid rafts formation
Rafts coalescence	T-cell activation, immune synapse formation
Lck activation	ZAP-70, ITAM phosphorylation
Linker of activated T cells activation	Signalling platform
Fyn activation	ZAP-70, ITAM phosphorylation
ZAP-70 activation	Linker of activated T cells activation
Extracellular signal-regulated kinase activation	Late T-cell activation, proliferation
p38 activation	Late T-cell activation, proliferation
Proteasome activity	NF-κB relocalization