title: IgG subclass distribution of anti-ADAMTS13 antibodies in patients with acquired thrombotic thrombocytopenic purpura.
abstract: BACKGROUND
  ADAMTS13-neutralizing IgG autoantibodies are the major cause of acquired thrombotic thrombocytopenic purpura (TTP).
  
  
  OBJECTIVE
  To analyze the IgG subclass distribution of anti-ADAMTS13 antibodies and a potential relationship between subclass distribution and disease prognosis.
  
  
  METHODS
  An enzyme-linked immunosorbent assay-based method was used to quantify the relative amounts of IgG subclasses of anti-ADAMTS13 antibodies in acquired TTP plasma.
  
  
  RESULTS
  IgG(4) (52/58, 90%) was the most prevalent IgG subclass in patients with acquired TTP, followed by IgG(1) (52%), IgG(2) (50%), and IgG(3) (33%). IgG(4) was found either alone (17/52) or with other IgG subclasses (35/52). IgG(4) was not detected in 10% of the patients. There was an inverse correlation between the frequency and abundance of IgG(4) and IgG(1) antibodies (P < 0.01). Patients with high IgG(4) levels and undetectable IgG(1) are more prone to relapse than patients with low IgG(4) levels and detectable IgG(1).
  
  
  CONCLUSIONS
  All IgG subclasses of anti-ADAMTS13 antibodies were detected in patients with acquired TTP, with IgG(4), followed by IgG(1), antibodies dominating the anti-ADAMTS13 immune response. Levels of IgG(4) could be useful for the identification of patients at risk of disease recurrence.
authors.affiliation: Department of Discovery Research and Technical Assessment, Baxter BioScience, 1220 Vienna, Austria.
authors.forename: S
authors.initials: S
authors.lastname: Ferrari
authors.forename: G C
authors.initials: GC
authors.lastname: Mudde
authors.forename: M
authors.initials: M
authors.lastname: Rieger
authors.forename: A
authors.initials: A
authors.lastname: Veyradier
authors.forename: J A
authors.initials: JA
authors.lastname: Kremer Hovinga
authors.forename: F
authors.initials: F
authors.lastname: Scheiflinger
mesh_terms: D051722:ADAM Proteins / Q000037:antagonists & inhibitors / Q000276:immunology*; D000071120:ADAMTS13 Protein; D000293:Adolescent; D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000145:classification* / Q000276:immunology; D001324:Autoantigens / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007074:Immunoglobulin G / Q000145:classification* / Q000276:immunology; D007132:Immunoglobulin Isotypes / Q000276:immunology; D008180:Lupus Erythematosus, Systemic / Q000150:complications / Q000276:immunology; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000276:immunology; D011247:Pregnancy; D011250:Pregnancy Complications, Hematologic / Q000276:immunology; D011644:Puerperal Disorders / Q000276:immunology; D011697:Purpura, Thrombotic Thrombocytopenic / Q000276:immunology*; D055815:Young Adult
chemical_list: D001323:Autoantibodies; D001324:Autoantigens; D007074:Immunoglobulin G; D007132:Immunoglobulin Isotypes; D051722:ADAM Proteins; D000071120:ADAMTS13 Protein; C099604:ADAMTS13 protein, human