Measuring receptor-mediated cell adhesion under flow : cell-free systems.

Leukocytes must bind to vascular endothelium under conditions of flow to perform their appropriate physiological functions, which require trafficking into and out of the tissue space surrounding blood vessels. Trafficking into tissues is required of neutrophils during the acute inflammatory response, and during trafficking of lymphocytes into lymphoid tissue. Egress from blood lumen to tissue involves a series of adhesion-dependent steps, each of which involve different leukocyte adhesion receptors and counterreceptors on the endothelium. Transient adhesion, or rolling, of leukocytes over endothelial cells is a prerequisite to firm attachment and transendothelial migration (1,2).