Interferon-γ Stimulates the Expression of CX3CL1/Fractalkine in Cultured Human Endothelial Cells

CX3CL1/Fractalkine, a CX3C chemokine, is a potent agonist for the chemotaxis and adhesion of monocytes and lymphocytes. It was first identified as a membrane protein in endothelial cells activated with IL-1 or TNF-α. We have found the enhanced expression of fractalkine in human umbilical vein endothelial cells stimulated with interferon-γ (IFN-γ). Pretreatment of the cells with cycloheximide did not inhibit the expression of fractalkine mRNA. The majority of fractalkine protein was found in the cell lysate, and an antibody-blocking experiment disclosed that fractalkine contributes to the adhesion of mononuclear cells to endothelial monolayers stimulated with IFN-γ. Vascular endothelial cells produce fractalkine in response to IFN-γ, and this may play an important role in immune responses by eliciting a traffic of mononuclear cells through the vascular wall.