The role of fractalkine in the recruitment of monocytes to the endothelium

Recombinant fractalkine possesses both chemoattractive and adhesive propert ies in vitro. Previous studies have demonstrated an upregulation of this mo lecule on the membranes of activated human endothelial cells and hypothesis ed that fractalkine plays a role in the recruitment and adherence of monocy tes to the activated endothelium. Here we present data analysing both the a dhesive and chemoattractive properties of this chemokine expressed by activ ated human umbilical vein endothelial cells. We demonstrate that both recom binant fractalkine and endogenously produced fractalkine function as adhesi on molecules, tethering monocytes to the endothelium. However, our data dem onstrate that although recombinant fractalkine has the potential to functio n as a potent monocyte chemoattractant, the endogenous fractalkine cleaved from activated human umbilical vein endothelial cells is not responsible fo r the observed chemotaxis in this model. Instead, we show that monocyte che moattractant protein-1 (MCP-1), secreted from the activated human umbilical vein endothelial cells, is responsible for the chemotaxis of these monocyt es. (C) 2000 Elsevier Science B.V. All rights reserved.