EXPRESSION OF FUNCTIONAL TISSUE FACTOR ON SMALL VESICLES OF LIPOPOLYSACCHARIDE-STIMULATED HUMAN VASCULAR ENDOTHELIAL-CELLS

We examined tissue factor expression on lipopolysaccharide-stimulated endothelial cells and their small vesicles by using specific antibodie s and flow cytometry. Tissue factor functional activity was also asses sed by activation of factor X, Endothelial cells were stimulated with 10 mu g/ml of lipopolysaccharide in M-199/bovine serum albumin. Flow c ytometry showed that expression of tissue factor on endothelial cells reached a maximum at 6 hours after stimulation, whereas that on small vesicles reached a maximum after 12 hours. Factor X activation mediate d by factor VIIa and tissue factor was observed over a similar time co urse and was inhibited by the addition of antitissue factor antibody. Immunoelectron microscopy suggested that small vesicles with expressio n of some tissue factor were produced from the surface of endothelial cells. Our findings thus showed that tissue factor on endothelial cell s produced by lipopolysaccharide stimulation was partly released to sm all vesicles. This may cause disseminated intravascular coagulation an d related coagulation disorders. (C) 1998 Elsevier Science Ltd.