title: Complement factor H functional assay may help to monitor atypical haemolytic uraemic syndrome: a pilot study.
abstract: BACKGROUND
  Atypical haemolytic uraemic syndrome (aHUS) results from uncontrolled complement system activation. Complement factor H gene mutations are common causes of aHUS. Plasmatherapy, including plasma infusions and/or plasma exchanges, has been tried in this setting with various successes. At present, we lack a specific marker to monitor functional factor H deficiency-related aHUS.
  
  
  METHODS
  We report the use of factor H functional assay in three patients with atypical haemolytic uraemic syndrome. This assay is based on the requirement of soluble complement regulators that bind sheep red cells to prevent haemolysis. As factor H is highly abundant in the plasma, its defect results in haemolysis. Factor H activity was also measured among plasma donors.
  
  
  RESULTS
  One patient suffered from a plasma-dependent form of atypical haemolytic uraemic syndrome. Plasma exchanges restored higher factor H activity and were associated with a 15-months disease-free period. In the two other patients, one with a failing renal graft and the other on chronic dialysis, a bout of thrombotic microangiopathy was preceded by a drop of haemolytic activity below normal values. Plasma from healthy donors (N=65) showed only minimal variations of Factor H activity (mean activity: 98.3%, SD=4.0).
  
  
  CONCLUSIONS
  These preliminary data suggest that factor H activity could be of interest in both the diagnosis and the treatment by plasmatherapy of factor H-related aHUS.
authors.affiliation: Department of Nephrology, Dialysis and Transplantation, Erasme Academic Hospital, Université Libre de Bruxelles, Brussels, Belgium. annick.massart@ulb.ac.be
authors.forename: A
authors.initials: A
authors.lastname: Massart
authors.forename: S
authors.initials: S
authors.lastname: Golmarvi
authors.forename: S
authors.initials: S
authors.lastname: Hachimi-Idrissi
authors.forename: E
authors.initials: E
authors.lastname: Broeders
authors.forename: Y
authors.initials: Y
authors.lastname: Tournay
authors.forename: J
authors.initials: J
authors.lastname: Nortier
authors.forename: D
authors.initials: D
authors.lastname: Abramowicz
authors.forename: C
authors.initials: C
authors.lastname: Tielemans
authors.forename: P
authors.initials: P
authors.lastname: Stordeur
mesh_terms: D000328:Adult; D000818:Animals; D065766:Atypical Hemolytic Uremic Syndrome; D015415:Biomarkers / Q000032:analysis; D016022:Case-Control Studies; D002675:Child, Preschool; D017242:Complement Factor H / Q000032:analysis / Q000235:genetics; D015941:Complement Hemolytic Activity Assay / Q000379:methods*; D004912:Erythrocytes / Q000502:physiology; D005260:Female; D006463:Hemolytic-Uremic Syndrome / Q000175:diagnosis*; D006801:Humans; D008297:Male; D010865:Pilot Projects; D012756:Sheep; D055815:Young Adult
chemical_list: D015415:Biomarkers; C493495:CFH protein, human; D017242:Complement Factor H