Adhesion Molecules are molecules that "stick" to specific cells and thereby "capture" them. This is the way that the body uses to bring specific cells to particular sites. It is used in many biological functions and is vital to the immune system and immunological response.
Within the immune system, adhesion molecules are used to draw specific lymphocytes to a site of infection or injury. Signalling molecules, called cytokines, especially the chemokines, are released by white blood cells (leukocytes) that are already on the scene. The chemokines migrate to the inner layer of blood and lymph vessels (the endothelial layer) causing specific adhesion molecules to be expressed on the surface of the endothelial cells. These act like hooks, catching specific leukocytes as they flow past in the blood. Having been captured, the target leukocytes are allowed to squeeze through in between the endothelial cells. Once through, they migrate to the site of infection by following the gradient of chemokines. This last stage of the journey is known as chemotaxis.
Adhesion molecules, especially a sub-group called selectins, are believed to play a pivotal role in several chronic immune diseases.
Adhesion Molecule links:
Dissecting the modes of interactions amongst cell adhesion molecules
Adhesion Receptor Classification Large Diagram
Inflammation : The Leukocyte Adhesion Cascade
4 IFNg/IL-10 and Th1/Th2
Cytokines, chemokines and adhesion molecules in lymphocyte infiltration