title: [Measurement of plasma von Willebrand factor cleaving protease in patients with varied thrombotic microangiopathy].
abstract: Thrombotic thrombocytopenic purpura(TTP) is a multisystem disorders characterized by thrombocytopenia, microangiopathic hemolytic anemia associated with red cell fragmentation, and neurological and renal symptoms. Plasma of patients with TTP has been shown to contain unusually large von Willebrand factor(vWF) multimers that may cause platelet agglutination in vivo. Recently, a metalloprotease responsible for cleavage of vWF multimers has been isolated from normal human plasma and was found to be deficient in some patients with TTP. We examined the activity of the vWF-cleaving protease(vWF-CP), by modified Furlan's method, in plasma from patients with a familial TTP, 3 acquired TTP, 4 thrombotic microangiopathy(TMA) and 2 veno-occlusive disease(VOD) associated after allo-BMT. Diluted plasma samples of patients were incubated with protease-free vWF purified from normal human plasma, in the presence of urea and barium ions. The extent of vWF degradation was assayed by electrophoresis in SDS-agarose gels and immunoblotting. Activity of vWF-CP from 12 normal plasma have been shown as 77-180%(average 115%), whereas, no vWF-CP(below 5%) was observed in plasma from familial TTP, before and after plasma exchange, although FFP infusion therapy has been effective for this patient to recover thrombocytopenia. In 3 acquired TTP, 2 patients showed lack of vWF-CP activity in plasma, and inhibitors against vWF-CP have been elucidated by plasma cross-mixing test. After extensive plasma exchange and FFP infusion followed by corticosteroid therapy, normal vWF-CP was recovered in plasma from 2 acquired TTP patients. Among BMT patients, plasma from 4 BMT-TMA showed normal vWF-CP activities as 55-111%, whereas plasma from 2 BMT-VOD revealed low vWF-CP activity, as 24% and 37%, respectively. Thus, measurement of vWF-CP is crucial to predict differentiation of primary forms of TMA to establish the pathogenesis in varied endothelial dysfunction.
authors.affiliation: Department of Laboratory Medicine, School of Medicine, Keio University, Sinjuku-ku, Tokyo 161-8582.
authors.forename: Hisako
authors.initials: H
authors.lastname: Katagiri
authors.forename: Yohko
authors.initials: Y
authors.lastname: Kawai
authors.forename: Noriko
authors.initials: N
authors.lastname: Sugizaki
authors.forename: Kazuo
authors.initials: K
authors.lastname: Sakai
authors.forename: Makoto
authors.initials: M
authors.lastname: Handa
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Okamoto
authors.forename: Kiyoaki
authors.initials: K
authors.lastname: Watanabe
mesh_terms: D051722:ADAM Proteins; D000071120:ADAMTS13 Protein; D015415:Biomarkers / Q000097:blood; D016026:Bone Marrow Transplantation / Q000009:adverse effects; D005260:Female; D006801:Humans; D008297:Male; D008666:Metalloendopeptidases / Q000097:blood*; D016491:Peripheral Vascular Diseases / Q000175:diagnosis* / Q000209:etiology; D011697:Purpura, Thrombotic Thrombocytopenic / Q000150:complications; D013927:Thrombosis / Q000175:diagnosis* / Q000209:etiology
chemical_list: D015415:Biomarkers; D051722:ADAM Proteins; D008666:Metalloendopeptidases; D000071120:ADAMTS13 Protein; C099604:ADAMTS13 protein, human