title: In vivo assessment with prick-to-prick testing and double-blind, placebo-controlled food challenge of allergenicity of apple cultivars.
abstract: BACKGROUND
  Apple cultivars have been reported to differ in allergenicity on the basis of in vitro and skin prick tests with apple extracts.
  
  
  OBJECTIVE
  We sought to evaluate the efficacy of the prick-to-prick method in assessing differences in allergenicity of apple cultivars and to confirm differences by means of double-blind, placebo-controlled food challenge (DBPCFC).
  
  
  METHODS
  Intra-assay and intracultivar variation of prick-to-prick test results were determined in 6 Dutch and 8 Spanish patients with apple allergy by using 5 apples of the cultivars Golden Delicious, Fuji, and Ecolette in duplicate. In addition, 21 cultivars were screened for allergenicity in 15 Dutch patients with birch pollen and apple allergy. Two selected cultivars (Golden Delicious and Santana) were tested with DBPCFCs. The influence of storage conditions on allergenicity was assessed in 5 cultivars.
  
  
  RESULTS
  Intra-assay variation of skin prick testing was 3.9%, and intracultivar variation was 4.1%. A ranking of 21 cultivars was made on the basis of prick-to-prick tests in 9 patients. Apple cultivars were classified as of low, intermediate, and high allergenicity, with a significant difference between low and high allergenicity (P < .001). A significant difference in allergenicity determined between Golden Delicious and Santana cultivars (P < .05) was confirmed by means of DBPCFC. With 5 cultivars, controlled atmosphere (2.5% oxygen/1% carbon dioxide) was shown to reduce allergenicity (P < .001) by 15% compared with storage at 2 degrees C.
  
  
  CONCLUSIONS
  Prick-to-prick testing with fresh apples is a reproducible method of assessing allergenicity. Apples can be classified as of low or high allergenicity for the majority of patients. This was confirmed by using DBPCFCs. Selection of cultivars and control of storage conditions are both viable strategies for reduction of symptoms in patients with apple allergy.
authors.affiliation: Department of Dermatology, University Hospital Utrecht, The Netherlands. S.Bolhaar@umcutrecht.nl
authors.forename: Suzanne T H P
authors.initials: ST
authors.lastname: Bolhaar
authors.forename: W Eric
authors.initials: WE
authors.lastname: van de Weg
authors.forename: Ronald
authors.initials: R
authors.lastname: van Ree
authors.forename: Eloina
authors.initials: E
authors.lastname: Gonzalez-Mancebo
authors.forename: Laurian
authors.initials: L
authors.lastname: Zuidmeer
authors.forename: Carla A F M
authors.initials: CA
authors.lastname: Bruijnzeel-Koomen
authors.forename: Montserrat
authors.initials: M
authors.lastname: Fernandez-Rivas
authors.forename: Johannes
authors.initials: J
authors.lastname: Jansen
authors.forename: Karin
authors.initials: K
authors.lastname: Hoffmann-Sommergruber
authors.forename: André C
authors.initials: AC
authors.lastname: Knulst
authors.forename: Luud J W J
authors.initials: LJ
authors.lastname: Gilissen
mesh_terms: D000485:Allergens / Q000276:immunology*; D004311:Double-Blind Method; D005512:Food Hypersensitivity / Q000175:diagnosis* / Q000276:immunology*; D006801:Humans; D027845:Malus / Q000009:adverse effects* / Q000145:classification* / Q000276:immunology; D015203:Reproducibility of Results; D012882:Skin Tests / Q000379:methods* / Q000592:standards
chemical_list: D000485:Allergens