|Home | About | Journals | Submit | Contact Us | Français|
Classical αβ T cells protect the host by monitoring intracellular and extracellular proteins in a two-step process. The first step is protein degradation and combining with a major histocompatibility complex (MHC) molecule leading to surface expression of this amalgam (antigen processing). The second step is the interaction of the T cell receptor (TCR) with the MHC-peptide complex leading to signaling in the T cells (antigen recognition). The context for this interaction is a T cell-antigen presenting cell (APC) junction known as an immunological synapse if symmetric and stable and that we have referred to as a kinapse if it is asymmetric and mobile. The physiological recognition of ligand takes place most efficiently in the filamentous (F)-actin rich lamellipodium and is F-actin dependent in stages of formation, triggering and myosin II dependent for signal amplification. This review discussed how these concepts emerged from early studies on adhesion, signaling and cell biology of T cells.
The adaptive immune system is a sensory organ that monitors our inner spaces for evidence of infection or cancer, regulates steady state microbiota and avoids self injury (Krogsgaard and Davis, 2005). The primary filter for this sensor is the dendritic cell (DC), which samples tissue spaces and interfaces for novel macromolecular information (Steinman et al., 2003). DC respond to tissues injury and detect conserved microbial structures leading to changes in DC signals to T lymphocyte (T cells), to shape an appropriate response (Trombetta and Mellman, 2005; West et al., 2004). The largest part of the information is in the form of proteins broken down into peptides that form complexes with surface molecules of the major histocompatibility complex (MHC-peptide complexes) that allow DCs to share this information with T cells expressing the T cell antigen receptors (TCR). An individual has a few hundred T cells that can detect any foreign MHC-peptide complex with single mol