title: Von Willebrand factor cleaving protease (ADAMTS-13) in 123 patients with connective tissue diseases (systemic lupus erythematosus and systemic sclerosis).
abstract: OBJECTIVE
  Autoantibodies inactivating the von Willebrand factor (VWF) cleaving protease, ADAMTS-13, are among the most frequent causes of thrombotic thrombocytopenic purpura (TTP). We evaluated whether or not ADAMTS-13 deficiency and autoantibodies inactivating the protease prevalent in patients with the prototypic autoimmune diseases systemic lupus erythematosus (SLE) and systemic sclerosis (SSc).
  
  
  METHODS
  We measured, in parallel, the protease and VWF antigen (VWF:Ag) in 123 patients, 36 of whom had SLE and 87 of whom had SSc. In 14 patients with either disease who had low plasma protease levels (below 40%) we also looked for anti-ADAMTS-13 inactivating antibodies.
  
  
  RESULTS
  ADAMTS-13 levels were significantly lower in SLE (p=0.0013) and in SSc (p=0.0002) than in normal controls. No anti-ADAMTS activity was measurable in patients with low ADAMTS-13 levels. VWF:Ag was high in both SLE and SSc (p=0.001).
  
  
  CONCLUSIONS
  Systemic connective tissue diseases are other conditions besides TTP that are associated in some instances with low but detectable levels of ADAMTS-13. Autoantibodies inactivating protease activity are not the cause of the low plasma levels of ADAMTS-13.
authors.affiliation: Angelo Bianchi Bonomi Hemophilia and Thrombosis Center and Department of Internal Medicine, IRCCS maggiore Hospital and University of Milan, Milan, Italy. pmmannucci@libero.it
authors.forename: Pier Mannuccio
authors.initials: PM
authors.lastname: Mannucci
authors.forename: Massimo
authors.initials: M
authors.lastname: Vanoli
authors.forename: Ileana
authors.initials: I
authors.lastname: Forza
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Canciani
authors.forename: Raffaella
authors.initials: R
authors.lastname: Scorza
mesh_terms: D051722:ADAM Proteins; D000071120:ADAMTS13 Protein; D000328:Adult; D001323:Autoantibodies / Q000097:blood; D005260:Female; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000097:blood* / Q000201:enzymology*; D008297:Male; D008666:Metalloendopeptidases / Q000097:blood* / Q000276:immunology; D008875:Middle Aged; D012595:Scleroderma, Systemic / Q000097:blood* / Q000201:enzymology*; D014841:von Willebrand Factor / Q000378:metabolism
chemical_list: D001323:Autoantibodies; D014841:von Willebrand Factor; D051722:ADAM Proteins; D008666:Metalloendopeptidases; D000071120:ADAMTS13 Protein; C099604:ADAMTS13 protein, human