Information transfer at the immunological synapse

Antigen specific activation of T lymphocytes requires the interaction of th eir clonally distributed T-cell receptors with plasma membrane ligands comp osed of foreign peptide antigens bound to major histocompatibility complex molecules. For proliferation and differentiation to ensue, a variety of oth er adhesive and accessory proteins must also interact with their counter-re ceptors on the antigen-presenting cell to facilitate and complement the T-c ell receptor-antigen recognition event. Recent studies have revealed that t hese various proteins show an unexpected degree of spatial organization in the zone of cell-cell contact. This region of membrane approximation is now referred to as the 'immunological synapse' because of its functional analo gy to the site of intercellular information transfer between neurons. Here, we review the evidence for signaling-dependent control of the dynamic chan ges in protein distribution that gives rise to the synapse and try to relat e the emerging spatio-temporal information on synapse formation to T-cell b iology.