INCREASED VON-WILLEBRAND-FACTOR (VWF) BINDING TO PLATELETS ASSOCIATEDWITH IMPAIRED VWF BREAKDOWN IN THROMBOTIC THROMBOCYTOPENIC PURPURA

Thrombotic thrombocytopenic purpura (TTP) is a disorder of systemic pl atelet aggregation. Evidence has accumulated that the aggregating agon ist in TTP of all types is likely to be von Willebrand factor (vWf), e specially unusually large vWf multimers derived from endothelial cells . Recent evidence indicates that a metalloproteinase involved in vWf b reakdown is produced in inadequate amounts in children with chronic re lapsing TTP. Chronic relapsing TTP is, therefore, likely to be a conge nital enzyme deficiency. In adults with single episode or intermittent types of TTP, the vWf metalloproteinase is inhibited by autoantibodie s that are present either transiently or intermittently in patient blo od. Single episode and intermittent types of TTP in adults are likely to be short-term or recurrent autoimmune processes, respectively. (C) 1998 Wiley-Liss,Inc.