T-lymphocyte interactions with endothelium and extracellular matrix

T-lymphocyte movement out of the bloodstream and into tissue is critical to the success of these cells in their role in immunosurveillance. This process involves interactions of the T-cell with endothelium as well as with extracellular matrix. Central to these interactions are a number of T-cell adhesion molecules and their endothelial and extracellular matrix ligands. The identification and functional characterization of adhesion molecules have been the subject of intensive research in recent years. We highlight here the latest developments in this rapidly expanding field as they pertain to T- cell interactions with endothelial cells and extracellular matrix components, including: (1) identification of adhesion molecule families, including the selectins, mucins, integrins, immunoglobulin superfamily members, and cadherins; (2) elucidation of the multi-step adhesion cascade that mediates the rolling, arrest, and eventual diapedesis of T-cells through the vascular endothelium into the surrounding tissue; (3) the changes in adhesion molecule expression that accompany T-cell maturation and activation, and the impact of those changes on T-cell migration; (4) the functional relevance of the extracellular matrix for T-cell function; and (5) the clinical relevance of adhesion molecules and the potential for targeting these molecules for the amelioration of immune-mediated diseases.