Review The Immunological Synapse T. Klemmensen: The Immunological Synapse

Abstract. The induction of a proper adaptive immune response is dependent on the correct transfer of information between antigen-presenting cells (APCs) and antigen-specific T cells. Defects in information transfer may result in the development of diseases, e.g. immunodeficiencies and autoimmunity. A distinct 3-dimensional supramole-cular structure at the T cell/APC interface has been suggested to be involved in the information transfer. Due to its functional analogy to the neuronal synapse, the structure has been termed the “immunological synapse ” (IS). Here, we review molecular aspects concerning IS formation, appearance, and cessation. In addition, proposed functions of the IS are discussed. The process of IS formation occurs in a sequential manner, initially causing a remarkable large-scale redistribution of a number of integral membrane and cytosolic proteins. At the T cell/APC interface the structure comprises in its nascent stage a non-random pattern of protein distribution. The protein pattern is regulated during development of the mature IS and is finally organized into concentric rings of co-receptors and adhesive molecules surrounding the T cell antigen receptor (TCR). The relocations of proteins are influenced by passive as well as active mechanisms. Considering the IS as a device enabling cell-cell com-munication, clarification of its exact function is of huge general as well as therapeutic interest. Key words: immunological synapse; signaling; T cell; TCR; MHC