Adsorption and coagulability of fibrinogen on atheromatous lipid surfaces

Fibrinogen, the precursor of the blood clot matrix and a major constituent of atherosclerotic lesions, is shown to adsorb with high affinity to hydrophobic beads coated with cholesteryl oleate, cholesterol, or loosely packed lecithin. The quantity of fibrinogen that binds to cholesterol- or lecithin-coated beads decreases as the surface concentration of the lipid increases; densely packed films of lecithin bind little, if any, of the protein. In sharp contrast, the appreciable quantity of fibrinogen that binds to cholesteryl oleate-coated beads is indifferent to the surface concentration of that lipid. Not unexpectedly, the quantity of fibrinogen that binds to beads coated with mixtures of cholesteryl oleate and lecithin increases with increasing concentration of the cholesteryl ester. When bound, fibrinogen can be converted by thrombin to fibrin and nucleate clot formation as manifested by the aggregation of stirred beads. These results indicate that hydrophobic, atheromatous lipid surfaces, particularly those rich in cholesteryl esters, may be predisposed to thrombosis by virtue of their inherent capacity to bind functional fibrinogen.