Regulatory mechanisms underlying T cell integrin receptor function

Adhesion molecules allow lymphocytes to interact with and respond to the extracellular environment. Since these interactions must be essentially transient in nature, the function of lymphocyte adhesion molecules must be precisely regulated. Studies of integrin receptors vividly illustrate the various mechanisms by which the function of these adhesion molecules can be regulated. These include: (1) activation-dependent changes in functional activity; (2) changes in levels of expression due to differentiation events; (3) cell-specific differences in integrin binding; and (4) differential binding to distinct ligands by the same integrin. These mechanisms provide highly precise and specific modes of regulating lymphocyte interactions with a wide variety of potential counter-receptors and ligands.