title: CD63 expression on basophils as a tool for the diagnosis of pollen-associated food allergy: sensitivity and specificity.
abstract: BACKGROUND
  Basophil activation is associated with the expression of CD63. Because allergens can induce basophil activation by cross-linking specific IgE, increased CD63 expression has been proposed as a novel in vitro test for immediate type allergy.
  
  
  OBJECTIVE
  We compared the CD63-based basophil activation test (BAT) in the diagnosis of allergy to carrot, celery and hazelnut with skin prick tests (SPT) and measurement of allergen-specific IgE.
  
  
  METHODS
  Twenty-nine patients with a history of an oral allergy syndrome induced by carrot, celery or hazelnut (n = 20 for each allergen) and 20 controls were studied. SPT were performed with standardized and native carrot, celery and hazelnut extracts. Allergen-specific IgE was determined by the CAP FEIA method and basophil activation was determined by flow cytometry upon double staining with anti-IgE/anti-CD63 mAb.
  
  
  RESULTS
  SPT with native carrot, celery and hazelnut showed sensitivities of 100%, 100% and 90%, and specificities of 80%, 80% and 90%. SPT with commercial extracts of the same allergens gave sensitivities of 85%, 80% and 85%, and specificities of 80%, 80% and 90%. Sensitivity of allergen-specific IgE and the BAT for carrot, celery and hazelnut was 80% vs. 85%, 70% vs. 85%, and 80% vs. 90%, with corresponding specificities of 80% vs. 85%, 80% vs. 80%, and 95% vs. 90%. The cut-off for a positive BAT was 10% CD63+ basophils. Moreover, there was a positive correlation between IgE reactivity and the number of CD63+ basophils for all food allergens (carrot: r = 0.69, celery: r = 0.67, hazelnut: r = 0.66).
  
  
  CONCLUSIONS
  Quantification of basophil activation by CD63 expression is a valuable new in vitro method for diagnosis of immediate type food sensitization. Although double-blind placebo-controlled food challenges remain the gold standard, the CD63-based BAT may supplement routine diagnostic tests such as SPT or allergen-specific IgE in the future.
authors.affiliation: Department of Dermatology and Allergology and Institute of Biometry, University hospital of RWTH Aachen, Aachen, Germany. serdmann@ukaachen.de
authors.forename: S M
authors.initials: SM
authors.lastname: Erdmann
authors.forename: N
authors.initials: N
authors.lastname: Heussen
authors.forename: S
authors.initials: S
authors.lastname: Moll-Slodowy
authors.forename: H F
authors.initials: HF
authors.lastname: Merk
authors.forename: B
authors.initials: B
authors.lastname: Sachs
mesh_terms: D015703:Antigens, CD / Q000097:blood*; D015549:Basophil Degranulation Test / Q000379:methods; D001491:Basophils / Q000378:metabolism*; D015415:Biomarkers / Q000097:blood; D015815:Cell Adhesion Molecules / Q000378:metabolism; D005434:Flow Cytometry / Q000379:methods; D005512:Food Hypersensitivity / Q000175:diagnosis*; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood; D021184:Nut Hypersensitivity / Q000175:diagnosis; D010980:Platelet Membrane Glycoproteins; D011058:Pollen / Q000009:adverse effects*; D012680:Sensitivity and Specificity; D012882:Skin Tests / Q000379:methods; D060149:Tetraspanin 30; D014675:Vegetables / Q000009:adverse effects
chemical_list: D015703:Antigens, CD; D015415:Biomarkers; C554586:CD63 protein, human; D015815:Cell Adhesion Molecules; D010980:Platelet Membrane Glycoproteins; D060149:Tetraspanin 30; D007073:Immunoglobulin E