SELECTINS AND MECHANISMS OF SIGNAL-TRANSDUCTION

Leukocyte emigration is essential in both lymphocyte homing, as a cent ral part of immune surveillance, and in leukocyte invasion at sites of inflammation., The emigration of leukocytes requires the interplay of adhesion molecules of the selectin and integrin families and chemokin es. Selectin-dependent cell-cell interaction is essential in localizin g leukocytes within tissues by promoting the rolling of leukocytes alo ng the endothelial cell surface before development of tight adhesion a nd subsequent transendothelial migration., Selectins also play an acti ve role in the initiation of intracellular signaling pathways and regu lation of cell-cell interactions involving monocytes, lymphocytes, pla telets, and endothelial cells, This review focuses mainly on the emerg ing evidence of biochemical signaling mechanisms involved in the regul ation of selectin-dependent leukocyte activation and adhesion, as well as the critical role played by selectins as leukocyte stimulatory mol ecules, This evidence has serious implications regarding the developme nt of immune and inflammatory responses, This article Trill also revie w key structural features of the selectin receptors, A summary is prov ided of our current understanding of the specific molecular interactio n occurring between these adhesion molecules and their counter-recepto rs, focusing on the critical roles they may play in the regulation of functional responses.