Prognostic value of anti-ADAMTS 13 antibody features (Ig isotype, titer, and inhibitory effect) in a cohort of 35 adult French patients undergoing a first episode of thrombotic microangiopathy with undetectable ADAMTS 13 activity

Blood. 2007 Apr 1;109(7):2815-22. doi: 10.1182/blood-2006-02-006064.


To study both the pathophysiologic and the prognostic value of ADAMTS13 in thrombotic microangiopathies (TMAs), we enrolled a cohort of 35 adult patients combining a first acute episode of TMA, an undetectable (below 5%) ADAMTS13 activity in plasma, and no clinical background such as sepsis, cancer, HIV, and transplantation. All patients were treated by steroids and plasma exchange, and an 18-month follow-up was scheduled. Remission was obtained in 32 patients (91.4%), and 3 patients died (8.6%) after the first attack. At presentation, ADAMTS13 antigen was decreased in 32 patients (91.4%), an ADAMTS13 inhibitor was detectable in 31 patients (89%), and an anti-ADAMTS13 IgG/IgM/IgA was present in 33 patients (94%). The 3 decedent patients were characterized by the association of several anti-ADAMTS13 Ig isotypes, including very high IgA titers, while mortality was independent of the ADAMTS13 inhibitor titer. In survivors, ADAMTS13 activity in remission increased to levels above 15% in 19 patients (59%) but remained undetectable in 13 patients (41%). Six patients relapsed either once or twice (19%) during the follow-up. High levels of inhibitory anti-ADAMTS13 IgG at presentation were associated with the persistence of an undetectable ADAMTS13 activity in remission, the latter being predictive for relapses within an 18-month delay.

MeSH terms

  • ADAM Proteins / blood
  • ADAM Proteins / deficiency*
  • ADAM Proteins / immunology*
  • ADAMTS13 Protein
  • Adolescent
  • Adult
  • Anemia, Hemolytic / blood
  • Anemia, Hemolytic / immunology
  • Autoantibodies / blood*
  • Cohort Studies
  • Female
  • France
  • Hemolytic-Uremic Syndrome / blood
  • Hemolytic-Uremic Syndrome / immunology
  • Humans
  • Immunoglobulin Isotypes / blood
  • Male
  • Middle Aged
  • Prognosis
  • Purpura, Thrombotic Thrombocytopenic / blood
  • Purpura, Thrombotic Thrombocytopenic / immunology
  • Thrombosis / blood
  • Thrombosis / immunology*
  • von Willebrand Factor / metabolism


  • Autoantibodies
  • Immunoglobulin Isotypes
  • von Willebrand Factor
  • ADAM Proteins
  • ADAMTS13 Protein
  • ADAMTS13 protein, human