The immunological synapse
The immunological synapse (IS) is a stable cell-cell junction between a thymus-derived lymphocyte (T cell) and an antigen-presenting cell (APC). The IS concept provides a number of insights into the T cell activation process. Firstly, it provides a stop signal that coordinates antigen recognition and T cell migration. Secondly, the essential role of the actin cytoskeleton in T cell activation is related to the role of actin in IS formation. Third, the sensitivity of T cell to agonist MHCp is related to the role of weakly interacting, but probably more abundant self MHCp in promoting IS formation. The IS provides a framework for orderly integration of the TCR and innate immune signals like CD28-CD80 interaction, and situations in which CD28 contributes to MC formation may open a door to autoimmunity. Finally, the IS may organize asymmetric cell divisions that are critical for T cell memory. The exact manner in which asymmetry is established and maintained, and the relationship of this process to the IS, is an area of great current interest. © 2010 Elsevier Inc. All rights reserved.