title: Distinct parameters of the basophil activation test reflect the severity and threshold of allergic reactions to peanut.
abstract: BACKGROUND
  The management of peanut allergy relies on allergen avoidance and epinephrine autoinjector for rescue treatment in patients at risk of anaphylaxis. Biomarkers of severity and threshold of allergic reactions to peanut could significantly improve the care for patients with peanut allergy.
  
  
  OBJECTIVE
  We sought to assess the utility of the basophil activation test (BAT) to predict the severity and threshold of reactivity to peanut during oral food challenges (OFCs).
  
  
  METHODS
  The severity of the allergic reaction and the threshold dose during OFCs to peanut were determined. Skin prick tests, measurements of specific IgE to peanut and its components, and BATs to peanut were performed on the day of the challenge.
  
  
  RESULTS
  Of the 124 children submitted to OFCs to peanut, 52 (median age, 5 years) reacted with clinical symptoms that ranged from mild oral symptoms to anaphylaxis. Severe reactions occurred in 41% of cases, and 57% reacted to 0.1 g or less of peanut protein. The ratio of the percentage of CD63(+) basophils after stimulation with peanut and after stimulation with anti-IgE (CD63 peanut/anti-IgE) was independently associated with severity (P = .001), whereas the basophil allergen threshold sensitivity CD-sens (1/EC₅₀ × 100, where EC₅₀ is half maximal effective concentration) value was independently associated with the threshold (P = .020) of allergic reactions to peanut during OFCs. Patients with CD63 peanut/anti-IgE levels of 1.3 or greater had an increased risk of severe reactions (relative risk, 3.4; 95% CI, 1.8-6.2). Patients with a CD-sens value of 84 or greater had an increased risk of reacting to 0.1 g or less of peanut protein (relative risk, 1.9; 95% CI, 1.3-2.8).
  
  
  CONCLUSIONS
  Basophil reactivity is associated with severity and basophil sensitivity is associated with the threshold of allergic reactions to peanut. CD63 peanut/anti-IgE and CD-sens values can be used to estimate the severity and threshold of allergic reactions during OFCs.
authors.affiliation: Department of Pediatric Allergy, Division of Asthma, Allergy & Lung Biology, 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.forename: Alexandra F
authors.initials: AF
authors.lastname: Santos
authors.affiliation: Department of Pediatric Allergy, Division of Asthma, Allergy & Lung Biology, King's College London, London, United Kingdom; MRC & Asthma UK Centre in Allergic Mechanisms of Asthma, London, United Kingdom.
authors.forename: George
authors.initials: G
authors.lastname: Du Toit
authors.affiliation: Department of Public Health Science, School of Medicine, King's College London, London, United Kingdom; National Institute for Health Research (NIHR), Biomedical Research Centre, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom.
authors.forename: Abdel
authors.initials: A
authors.lastname: Douiri
authors.affiliation: Department of Pediatric Allergy, Division of Asthma, Allergy & Lung Biology, King's College London, London, United Kingdom; MRC & Asthma UK Centre in Allergic Mechanisms of Asthma, London, United Kingdom.
authors.forename: Suzana
authors.initials: S
authors.lastname: Radulovic
authors.affiliation: Department of Pediatric Allergy, Division of Asthma, Allergy & Lung Biology, King's College London, London, United Kingdom; MRC & Asthma UK Centre in Allergic Mechanisms of Asthma, London, United Kingdom.
authors.forename: Alick
authors.initials: A
authors.lastname: Stephens
authors.affiliation: Department of Pediatric Allergy, Division of Asthma, Allergy & Lung Biology, King's College London, London, United Kingdom; MRC & Asthma UK Centre in Allergic Mechanisms of Asthma, London, United Kingdom.
authors.forename: Victor
authors.initials: V
authors.lastname: Turcanu
authors.affiliation: Department of Pediatric Allergy, Division of Asthma, Allergy & Lung Biology, 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.forename: Gideon
authors.initials: G
authors.lastname: Lack
mesh_terms: D000293:Adolescent; D010367:Arachis / Q000009:adverse effects* / Q000276:immunology; D001491:Basophils / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood; D007159:Immunologic Tests; D007223:Infant; D008297:Male; D021183:Peanut Hypersensitivity / Q000097:blood / Q000175:diagnosis* / Q000276:immunology; D012720:Severity of Illness Index; D060149:Tetraspanin 30 / Q000276:immunology
chemical_list: C554586:CD63 protein, human; D060149:Tetraspanin 30; D007073:Immunoglobulin E
keywords: Basophil activation test; CD-sens; CD203c; CD63; double-blind; peanut; peanut allergy; placebo-controlled food challenge; sensitivity; severity; threshold