title: Detection of basophil-activating IgG autoantibodies in chronic idiopathic urticaria by induction of CD 63.
abstract: BACKGROUND
  Approximately 40% to 50% of patients with chronic idiopathic urticaria (CIU) have functional IgG autoantibodies against FcepsilonRIalpha or IgE, which induce histamine release from basophils and cutaneous mast cells. A positive autologous serum skin test response is believed to reflect the presence of these autoantibodies.
  
  
  OBJECTIVE
  We sought to further define the functional properties of and develop a sensitive functional assay for detection of autoantibodies in patients with CIU.
  
  
  METHODS
  Sera from patients with CIU (n=61) and sera from healthy control subjects (n=23) were incubated with donor basophils. Activation of basophils was determined on the basis of CD 63 surface expression, as analyzed on a FACScan flow cytometer.
  
  
  RESULTS
  A positive basophil activation test result was found in 51% of patients with CIU, and basophil-activating properties were present in the IgG fractions of sera. When both the in vitro test and the autologous serum skin test were considered, basophil/mast cell-activating autoantibodies were present in 62% of the patients. Patients with a positive basophil activation test result had a significantly higher prevalence of other autoantibodies, had more severe urticaria, and were more likely to have angioedema.
  
  
  CONCLUSIONS
  The results demonstrate the presence of basophil-activating autoantibodies in about 50% of patients with CIU. The data support the autoimmune cause of the disease and provide a simple test for detection of these autoantibodies.
authors.affiliation: Division of Clinical Immunology, University Hospital, Katholieke Universiteit Leuven, Belgium.
authors.forename: Ann
authors.initials: A
authors.lastname: De Swerdt
authors.forename: Caroline
authors.initials: C
authors.lastname: Van Den Keybus
authors.forename: Ahmad
authors.initials: A
authors.lastname: Kasran
authors.forename: Pascal
authors.initials: P
authors.lastname: Cadot
authors.forename: Karen
authors.initials: K
authors.lastname: Neyens
authors.forename: Lieve
authors.initials: L
authors.lastname: Coorevits
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Kochuyt
authors.forename: Hugo
authors.initials: H
authors.lastname: Degreef
authors.forename: Jan L
authors.initials: JL
authors.lastname: Ceuppens
mesh_terms: D000293:Adolescent; D000328:Adult; D000888:Antibodies, Anti-Idiotypic / Q000097:blood / Q000276:immunology; D015703:Antigens, CD / Q000276:immunology* / Q000378:metabolism; D001323:Autoantibodies / Q000097:blood* / Q000276:immunology; D001491:Basophils / Q000276:immunology*; D002908:Chronic Disease; D005434:Flow Cytometry; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology; D007074:Immunoglobulin G / Q000097:blood* / Q000276:immunology; D007158:Immunologic Techniques; D010980:Platelet Membrane Glycoproteins / Q000276:immunology* / Q000378:metabolism; D017455:Receptors, IgE / Q000276:immunology; D012882:Skin Tests; D060149:Tetraspanin 30; D014581:Urticaria / Q000097:blood / Q000276:immunology*
chemical_list: D000888:Antibodies, Anti-Idiotypic; D015703:Antigens, CD; D001323:Autoantibodies; C554586:CD63 protein, human; D007074:Immunoglobulin G; D010980:Platelet Membrane Glycoproteins; D017455:Receptors, IgE; D060149:Tetraspanin 30; D007073:Immunoglobulin E