This study demonstrates that when platelets are stimulated by thrombin in the presence of low concentrations of purified human fibrinogen (10 to 20 Lg/mL. final concentration) binding of released platelet von Willebrand factor (plt-vWF) to the platelet membrane is enhanced. This effect appears to be mediated by fibrin monomer produced by the action of thrombin on the fibrinogen in the incubatio...