Division of Hematology, Montefiore Medical Center and Albert Einstein College of Medicine, 111 E 210th St, Bronx, NY, USA. htsai@montefiore.org
In the circulation, a plasma metalloprotease, ADAMTS13, cleaves von Willebrand factor (vWF) in a shear-dependent manner. This article reviews the role of this cleavage in regulating vWF-platelet interaction and proposes a scheme for understanding how a deficiency of ADAMTS13 results in the development of microthrombi in patients with thrombotic thrombocytopenic purpura.