title: Frequently relapsing thrombotic thrombocytopenic purpura treated with cytotoxic immunosuppressive therapy.
abstract: OBJECTIVE
  Treatment of thrombotic thrombocytopenic purpura (TTP) with plasma exchange has reduced mortality rates from 90% in untreated cases to less than 20%. Despite plasma exchange, relapses may occur in as many as 40% of cases. Multiple relapses occur in a minority but pose a significant therapeutic challenge. Recent evidence supports the presence of an autoantibody which inhibits proteolysis of von Willebrand factor (vWF) in active TTP, allowing large multimers of vWF to form and promote platelet aggregation. Additional evidence suggests autoantibodies activate capillary endothelium and promote platelet aggregation in the microcirculation. Immunosuppression, thus, has a biologically plausible role in TTP. We describe three consecutive cases of relapsing TTP treated with cytotoxic therapy to highlight the potential role of immunosuppression.
  
  
  METHODS
  Cytotoxic immunosuppressive therapy with either cyclophosphamide or azathioprine was used in three consecutive patients with frequently relapsing TTP.
  
  
  RESULTS
  All three patients have maintained remissions of 8 to 10 months without recurrence.
  
  
  CONCLUSIONS
  Cytotoxic immunosuppressive therapy may have a role in inducing long-term remissions in recurrent TTP.
authors.affiliation: Divison of Hematology, Department of Medicine, University of Western Ontario, London, Ontario, Canada. dsallan@uwo.ca
authors.forename: D S
authors.initials: DS
authors.lastname: Allan
authors.forename: M J
authors.initials: MJ
authors.lastname: Kovacs
authors.forename: W F
authors.initials: WF
authors.lastname: Clark
mesh_terms: D000328:Adult; D001379:Azathioprine / Q000008:administration & dosage; D003520:Cyclophosphamide / Q000008:administration & dosage; D005260:Female; D006801:Humans; D007166:Immunosuppressive Agents / Q000008:administration & dosage*; D008875:Middle Aged; D010976:Platelet Count; D011697:Purpura, Thrombotic Thrombocytopenic / Q000188:drug therapy*; D012008:Recurrence; D012074:Remission Induction
chemical_list: D007166:Immunosuppressive Agents; D003520:Cyclophosphamide; D001379:Azathioprine