Sialyl Lewis(x)/E-selectin-mediate rolling in a cell-free system

Selectins mediate transient adhesion of neutrophils to stimulated endothelial cells at sites of inflammation by binding counter-receptors that present carbohydrates such as sialyl Lewis(x). We have developed a cell-free adhesion assay using sialyl Lewis(x)-coated microspheres and E-selectin-IgG chimera-coated substrates to investigate the premise that rolling primarily results from functional properties of selectin-carbohydrate bonds, whereas cellular morphology and signaling act as secondary effects. Sialyl Lewis(x)-coated microspheres attach to and roll over E-selectin-IgG chimera-coated substrates between the physiological wall shear stresses of 0.7 and 2 dynes/cm(2). Rolling velocities vary with time and depend on E-selectin-IgG chimera site density and wail hear stress. Our results show that sialyl Lewis(x) isa minimal functional recognition element required for rolling on E-selectin under flow.