New views of the immunological synapse: variations in assembly and function.

The interaction of T cells with antigen-presenting cells results in the formation of a contact face, termed the immunological synapse. The prototypical dynamics of this process are well established and involve cessation of crawling, a highly fluid 'immature' synapse phase during which signaling is initiated, and ultimately the formation of a 'mature' synapse characterized by centralized and peripheral supramolecular activating complexes. Ongoing research is directed towards defining how these supramolecular assemblies are formed and, more importantly, to what end. With regard to the former, progress has been made in defining the order in which various molecules are recruited to signaling centers in prototypical settings. With regard to the latter, however, the issue now appears more complex, as both developmental changes in T cells and variations in the environment appear to modulate features of mature synapse development. Although many details of the immunological synapse have been established, emerging evidence suggests a great variability in the ultimate form of these contacts and their effects on T-cell functions.