tailieunhanh - Báo cáo khoa học: Leukocyte–endothelial cell interactions

Leukocytes constantly patrol the vascular system in order to react promptly to infections when and where it is necessary. To fulfil this task, the cells have to enter secondary lymphoid organs and to emigrate into inflamed tissues, which requires them to cross the bar-rier of endothelial cells that line blood vessels. | ỊFEBS Journal MINIREVIEW SERIES Leukocyte-endothelial cell interactions Martin K. Wild and M. Gabriele Bixel Leukocytes constantly patrol the vascular system in order to react promptly to infections when and where it is necessary. To fulfil this task the cells have to enter secondary lymphoid organs and to emigrate into inflamed tissues which requires them to cross the barrier of endothelial cells that line blood vessels. Transendothelial migration into inflamed tissues is preceded by a sequence of leukocyte-endothelial cell interactions generally referred to as the multistep adhesion cascade Fig. 1 . The cascade is initiated by inflammatory signals that cause local activation of vascular endothelium. Activated endothelial cells express E- and P-selectin molecules that capture leukocytes from the bloodstream and mediate rolling of the cells by binding to glycoconjugate ligands on the leukocyte surface. Homing to secondary lymphoid organs is initiated by interactions of L-selectin expressed by leukocytes with glycoconjugates on high endothelial venules. Rolling allows the leukocytes to perceive and accumulate signals that are mediated by the binding of endothelial-bound chemokines to their leukocyte receptors. These signals lead to leukocyte activation resulting in a transfer of leukocyte integrins into a high affinity conformation. The integrins now allow the leukocytes to adhere firmly to the endothelium by interactions with intercellular adhesion molecule-1 and or vascular cell adhesion molecule-1. The leukocytes then migrate to sites where they can cross the endothelial layer using either a para-cellular pathway through intercellular junctions or a transcellular pathway through the endothelial cell body. This minireview series comprises five reviews that cover important aspects of leukocyte-endothelial cell interactions indicated in Fig. 1 . In the first review Markus Sperandio considers in vivo results on selectin-mediated leukocyte rolling. He describes the .