title: Novel nephelometric assay for measurement of complement 3d.
abstract: BACKGROUND
  This report describes a nephelometric assay for measuring complement 3d (C3d).
  
  
  METHODS
  C3d was separated from C3 and the other C3 split products by polyethylene glycol precipitation. The supernatant containing C3d was then measured by rate nephelometry in a Beckman Immage rate nephelometer using a specific antibody. Calibration was performed with dilutions of a standard, which was obtained by incubating a serum pool at 37 degrees C for 7 days. This incubation step allowed the activation and breakdown of C3 into C3d.
  
  
  RESULTS
  The assay was linear across the normal and pathological range. Precision studies showed within-run and between-run coefficients of variation of < 5% and < 6%, respectively. The nephelometric results are comparable with those obtained by radial immunodiffusion. Neither haemoglobin nor lipids interfere with the assay.
authors.affiliation: Laboratory Medicine, Immunology, University Hospitals Leuven, Belgium. xavier.bossuyt@uz.kuleuven.ac.be
authors.forename: Xavier
authors.initials: X
authors.lastname: Bossuyt
authors.forename: Lutgarde
authors.initials: L
authors.lastname: Sneyers
authors.forename: Godelieve
authors.initials: G
authors.lastname: Mariën
authors.forename: Guido
authors.initials: G
authors.lastname: Vranken
mesh_terms: D000937:Antigen-Antibody Reactions; D015933:Complement C3d / Q000032:analysis*; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D005779:Immunodiffusion / Q000379:methods; D008055:Lipids / Q000032:analysis; D009391:Nephelometry and Turbidimetry / Q000379:methods*; D012015:Reference Standards; D012016:Reference Values
chemical_list: D006454:Hemoglobins; D008055:Lipids; D015933:Complement C3d