APC, T cells, and the immune synapse.

CD4(+) T cells engage different activating cells during their generation in the bone marrow and thymus and during their homeostasis and activation in the periphery. During these processes, T cells or their precursors establish a molecular platform for communication in the interface between the two cells that is called immune synapse (IS). Here we review the current knowledge about those different IS. Apart from looking at the structure and signalling of the IS from the T cell region, we will also focus on the area of the IS partner, mostly antigen-presenting cells (APC). We will discuss the features of different APC and their role played in the control of the resulting activated or differentiated T cell. We will also demonstrate that despite 10 years of research into the subject, large areas of this field are yet to be explored. This will keep us busy for the years to come - new exciting results lie ahead of us.