The effects of surface chemistry and coagulation factors on fibrinogen adsorption from plasma.

Fibrinogen adsorption from plasma exhibits an unusual displacement phenomenon (the Vroman effect) in that decreases in adsorption occur after longer contact time or as the plasma concentration increases. Fibrinogen adsorption and the displacement effect were found to depend markedly on the nature of the surface, the time and temperature of adsorption, and to a lesser extent on certain contact activation factors. Displacement still occurred from plasmas lacking kininogens, factor IX, and prekallikrein, and from plasma that had been treated with BaSO4 to remove factors II, VII, IX, and X. Furthermore, displacement was also observed from fibrinogen solutions to which either albumin or hemoglobin had been added. In addition, competitive adsorption of binary protein mixtures was also shown to depend strongly on surface type. It therefore appears that fibrinogen adsorption from plasma is subject to similar if not identical competitive processes that occur in simpler protein mixtures. The final adsorption then reflects the influence of all the proteins in plasma, each competing for the limited number of adsorption sites according to the fundamental physical properties of surface activity and mass concentration.