title: Basophil activation test discriminates between allergy and tolerance in peanut-sensitized children.
abstract: BACKGROUND
  Most of the peanut-sensitized children do not have clinical peanut allergy. In equivocal cases, oral food challenges (OFCs) are required. However, OFCs are laborious and not without risk; thus, a test that could accurately diagnose peanut allergy and reduce the need for OFCs is desirable.
  
  
  OBJECTIVE
  To assess the performance of basophil activation test (BAT) as a diagnostic marker for peanut allergy.
  
  
  METHODS
  Peanut-allergic (n = 43), peanut-sensitized but tolerant (n = 36) and non-peanut-sensitized nonallergic (n = 25) children underwent skin prick test (SPT) and specific IgE (sIgE) to peanut and its components. BAT was performed using flow cytometry, and its diagnostic performance was evaluated in relation to allergy versus tolerance to peanut and validated in an independent population (n = 65).
  
  
  RESULTS
  BAT in peanut-allergic children showed a peanut dose-dependent upregulation of CD63 and CD203c while there was no significant response to peanut in peanut-sensitized but tolerant (P < .001) and non-peanut-sensitized nonallergic children (P < .001). BAT optimal diagnostic cutoffs showed 97% accuracy, 95% positive predictive value, and 98% negative predictive value. BAT allowed reducing the number of required OFCs by two-thirds. BAT proved particularly useful in cases in which specialists could not accurately diagnose peanut allergy with SPT and sIgE to peanut and to Arah2. Using a 2-step diagnostic approach in which BAT was performed only after equivocal SPT or Arah2-sIgE, BAT had a major effect (97% reduction) on the number of OFCs required.
  
  
  CONCLUSIONS
  BAT proved to be superior to other diagnostic tests in discriminating between peanut allergy and tolerance, particularly in difficult cases, and reduced the need for OFCs.
authors: Division of Asthma, Allergy & Lung Biology, Department of Pediatric Allergy, King's College London, London, United Kingdom; MRC & Asthma UK Centre in Allergic Mechanisms of Asthma, London, United Kingdom; Immunoallergology Department, Coimbra University Hospital, Coimbra, Portugal; Gulbenkian Programme for Advanced Medical Education, Lisbon, Portugal.
authors: Alexandra F
authors: AF
authors: Santos
authors: Department of Public Health Science, School of Medicine, King's College London, London, United Kingdom; National Institute for Health Research, Biomedical Research Centre, Guy's and St Thomas' Hospital NHS Foundation Trust, London, United Kingdom.
authors: Abdel
authors: A
authors: Douiri
authors: Division of Asthma, Allergy & Lung Biology, Department of Pediatric Allergy, King's College London, London, United Kingdom; MRC & Asthma UK Centre in Allergic Mechanisms of Asthma, London, United Kingdom.
authors: Natalia
authors: N
authors: Bécares
authors: Division of Asthma, Allergy & Lung Biology, Department of Pediatric Allergy, King's College London, London, United Kingdom; MRC & Asthma UK Centre in Allergic Mechanisms of Asthma, London, United Kingdom.
authors: Shih-Ying
authors: SY
authors: Wu
authors: Division of Asthma, Allergy & Lung Biology, Department of Pediatric Allergy, King's College London, London, United Kingdom; MRC & Asthma UK Centre in Allergic Mechanisms of Asthma, London, United Kingdom.
authors: Alick
authors: A
authors: Stephens
authors: Division of Asthma, Allergy & Lung Biology, Department of Pediatric Allergy, King's College London, London, United Kingdom; MRC & Asthma UK Centre in Allergic Mechanisms of Asthma, London, United Kingdom.
authors: Suzana
authors: S
authors: Radulovic
authors: Division of Asthma, Allergy & Lung Biology, Department of Pediatric Allergy, King's College London, London, United Kingdom; MRC & Asthma UK Centre in Allergic Mechanisms of Asthma, London, United Kingdom; National Institute for Health Research, Biomedical Research Centre, Guy's and St Thomas' Hospital NHS Foundation Trust, London, United Kingdom.
authors: Susan M H
authors: SM
authors: Chan
authors: Division of Asthma, Allergy & Lung Biology, Department of Pediatric Allergy, King's College London, London, United Kingdom; MRC & Asthma UK Centre in Allergic Mechanisms of Asthma, London, United Kingdom.
authors: Adam T
authors: AT
authors: Fox
authors: Division of Asthma, Allergy & Lung Biology, Department of Pediatric Allergy, King's College London, London, United Kingdom; MRC & Asthma UK Centre in Allergic Mechanisms of Asthma, London, United Kingdom.
authors: George
authors: G
authors: Du Toit
authors: Division of Asthma, Allergy & Lung Biology, Department of Pediatric Allergy, King's College London, London, United Kingdom; MRC & Asthma UK Centre in Allergic Mechanisms of Asthma, London, United Kingdom.
authors: Victor
authors: V
authors: Turcanu
authors: Division of Asthma, Allergy & Lung Biology, Department of Pediatric Allergy, King's College London, London, United Kingdom; MRC & Asthma UK Centre in Allergic Mechanisms of Asthma, London, United Kingdom. Electronic address: gideon.lack@kcl.ac.uk.
authors: Gideon
authors: G
authors: Lack
mesh_terms: D055516:2S Albumins, Plant / Q000276:immunology; D052179:Antigens, Plant / Q000276:immunology; D015549:Basophil Degranulation Test / Q000379:methods*; D002469:Cell Separation; D002648:Child; D002675:Child, Preschool; D004306:Dose-Response Relationship, Immunologic; D005260:Female; D005434:Flow Cytometry; D006023:Glycoproteins / Q000276:immunology; D006801:Humans; D007108:Immune Tolerance; D007073:Immunoglobulin E / Q000097:blood; D008297:Male; D021183:Peanut Hypersensitivity / Q000175:diagnosis*; D011237:Predictive Value of Tests; D011379:Prognosis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012882:Skin Tests
chemical_list: D055516:2S Albumins, Plant; D052179:Antigens, Plant; C500890:Ara h 2 allergen, Arachis hypogaea; D006023:Glycoproteins; D007073:Immunoglobulin E
keywords: Anaphylaxis; CD203c; CD63; ROC curve; basophil activation test; diagnosis; flow cytometry; food allergy; peanut allergy