von Willebrand factor binds to platelets and induces aggregation in platelet-type but not type IIB von Willebrand disease.

摘要: Platelet-type von Willebrand disease (vWD) and pseudo-vWD are two recently described intrinsic platelet defects characterized by enhanced ristocetin-induced agglutination in platelet-rich plasma. A similar finding is also typical of type IIB vWD, where it has been related to a factor (vWF) rather than abnormality. Platelet aggregation induced unmodified human vWF the absence other stimuli reported pseudo-vWD. In this study we demonstrate that induces platelet-type but not vWD. Aggregation observed when normal plasma cryoprecipitate or purified added Cryoprecipitate aggregates washed platelets, although at higher concentrations required for Purified vWF, however, significant platelets only added. EDTA inhibits vWF-induced aggregation. Its effect can be overcome calcium much less effectively magnesium ions. Unstimulated from patients with vWD bind 125I-vWF specific saturable manner. All different sized multimers become associated platelets. Both binding exhibit concentration dependence, suggesting correlation exists between these events. Removal ADP appropriate consuming systems without upon such Thrombin-induced as well These results site exposed on unstimulated The relatively high may explain lack vivo thrombocytopenia patients. Moreover, studies provide additional evidence diseases distinct pathogeneses.