The function of GPI-anchored proteins in T cell development, activation and regulation of homeostasis

Many glycosylphosphatidyl-inositol-anchored proteins (GPI-AP) are expressed on T lymphocytes. Ligand or mAb-mediated aggregation of all GPI-AP tested to date results in the initiation of signal transduction pathways via the a ctivation of src family protein tyrosine kinases. Src family kinases co-loc alise with GPI-AP in specialised sub-domains of the plasma membrane, referr ed to as detergent insoluble membrane microdomains (DIGS), which are though t to function as signalling platforms. GPI-AP may play a role in the regulation of T cell clonal expansion and eff ector functions at multiple levels, including the initiation of T cell acti vation through the antigen receptor complex, the regulation of ongoing resp onses supported by persisting antigen, as well as proliferative responses t o the major T cell growth factor, IL-2. Evidence supporting the role of GPI -AP in the regulation of T cell development, activation and homeostasis is discussed, as well as insights provided by studies in humans and mice lacki ng GPI-AP.