Specific von Willebrand factor–cleaving protease in thrombotic microangiopathies: a study of 111 cases

• Published in: Blood 2001-09, Vol.98 (6), p.1765-1772
• Main Authors: Veyradier, Agnès, Obert, Bernadette, Houllier, Anne, Meyer, Dominique, Girma, Jean-Pierre
• Format: Article
• Language: English
• Subjects: ADAM Proteins; ADAMTS13 Protein; Adult; Biological and medical sciences; Female; Follow-Up Studies; Hematologic and hematopoietic diseases; Hemolytic-Uremic Syndrome - blood; Hemolytic-Uremic Syndrome - diagnosis; Hemolytic-Uremic Syndrome - therapy; Humans; Male; Medical sciences; Metalloendopeptidases - antagonists & inhibitors; Metalloendopeptidases - metabolism; Platelet diseases and coagulopathies; Prospective Studies; Protease Inhibitors - metabolism; Purpura, Thrombotic Thrombocytopenic - blood; Purpura, Thrombotic Thrombocytopenic - diagnosis; Purpura, Thrombotic Thrombocytopenic - therapy; Remission Induction
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood.V98.6.1765

Retrospective studies of patients with thrombotic microangiopathies (TMAs) have shown that a deficient activity of von Willebrand factor (vWF)–cleaving protease is involved in thrombotic thrombocytopenic purpura (TTP) but not in the hemolytic-uremic syndrome (HUS). To further analyze the relevance of this enzymatic activity in TMA diagnosis, a 20-month multicenter study of vWF-cleaving protease activity was conducted in adult patients prospectively enrolled in the acute phase of TMA. Patients with sporadic (n = 85), intermittent (n = 21), or familial recurrent (n = 5) forms of TMA (66 manifesting as TTP and 45 as HUS) were included. TMA was either idiopathic (n = 42) or secondary to an identified clinical context (n = 69). vWF-cleaving protease activity was normal in 46 cases (7 TTP and 39 HUS) and decreased in 65 cases (59 TTP and 6 HUS). A protease inhibitor was detected in 31 cases and was observed only in patients manifesting TTP with a total absence of protease activity. Among the 111 patients, mean vWF antigen levels were increased and the multimeric distribution of vWF was very heterogeneous, showing either a defect of the high-molecular-weight forms (n = 40), a normal pattern (n = 21), or the presence of unusually large multimers (n = 50). Statistical analysis showed that vWF-protease deficiency was associated with the severity of thrombocytopenia (P < .01). This study emphasizes that vWF-cleaving protease deficiency specifically concerns a subgroup of TMA corresponding to the TTP entity.