Neutrophil adhesion to endothelial cells

Abstract

The emigration of neutrophils at sites of inflammation apparently requires intercellular adhesion. Initially, leukocyte adherence is observed in postcapillary venules where neutrophils roll along the luminal surface of the endothelial cells before stopping, changing shape, and migrating into the perivascular tissue. Recent evidence indicates that the adhesion molecules supporting the rolling phenomenon are distinct from those required for stopping and transmigration. The contribution of E-selectin (ELAM-1) to neutrophil adhesion and rolling was investigated using anti-E-selectin monoclonal antibody in an in vitro adhesion assay of isolated human neutrophils to murine L-cell monolayers stably transfected with human E-selectin cDNA. Isolated human neutrophils adhered to E-selectin expressing L-cell monolayers under physiological wall shear stress of 1.85 dynes/cm2 but not to untransfected L-cells or ICAM-1 expressing L-cells. 47.8 +/- 6.0% of these adherent cells were rolling at an average rolling velocity of 10.6 +/- 1.7 microns/second. This adhesion and rolling was almost completely blocked by anti-E-selectin monoclonal antibody. Monoclonal antibody to L-selectin also reduced adhesion to E-selectin expressing cells by 70%. Chemotactic stimulation of neutrophils reduced both the number of adherent and rolling cells and the average velocity of the rolling cells without influencing the percentage of attached cells that were rolling. Pretreatment with anti-CD18 monoclonal antibody did not reduce the adhesion of the activated neutrophils but reversed the reduction in velocity caused by activation of these cells. The inhibitory potential of the anti-E-selectin monoclonal antibody was much less pronounced in adhesion of isolated neutrophils to human umbilical vein endothelial cell monolayers under conditions of flow and was limited to one third of the total adhesion. The proportion of the adherent neutrophils which transmigrated to the subluminal space of the endothelial cell monolayers was independent of pretreatment with anti-E-selectin monoclonal antibody.