title: Basophil allergen threshold sensitivity and component-resolved diagnostics improve hazelnut allergy diagnosis.
abstract: BACKGROUND
  IgE sensitization to hazelnut is common, especially in birch endemic areas. However, its clinical significance often needs to be confirmed by a food challenge.
  
  
  OBJECTIVE
  To evaluate the clinical significance of IgE antibodies to hazelnut components and basophil allergen threshold sensitivity (CD-sens) to hazelnut, in relation to double-blind placebo-controlled food challenge (DBPCFC) in children with a suspected hazelnut allergy.
  
  
  METHODS
  Forty children underwent a DBPCFC. CD-sens to hazelnut as well as IgE antibodies to hazelnut and its components Cor a 1, Cor a 8, Cor a 9 and Cor a 14 were analysed. Serum tryptase was measured before, during and after DBPCFC.
  
  
  RESULTS
  Eight children had a positive DBPCFC, and all of them had a high CD-sens value to hazelnut. Of the 32 children that passed the DBPCFC, 31 were very low or negative in CD-sens. A positive DBPCFC corresponded with significantly higher CD-sens values (median 8.9, range 3.3-281) compared to children negative in challenge (median 0.05, range 0-34.7, P < 0.0001). Children positive in challenge also had higher levels of IgE-ab to Cor a 9 and Cor a 14 (P < 0.01 and P < 0.001, respectively) compared with those with a negative challenge. In relation to the results from DBPCFC, the sensitivity of CD-sens and IgE-ab to Cor a 14 was excellent (100%) and the specificity was very high (> 97% and > 94%, respectively). Five of the eight patients positive at challenge showed an increase in tryptase > 20% compared to tryptase baseline levels.
  
  
  CONCLUSIONS
  CD-sens and component-resolved diagnostics to hazelnut, used separately or in combination, may improve the diagnostic accuracy and safety and reduce overdiagnosis of hazelnut allergy.
authors.affiliation: Department of Clinical Science and Education, Södersjukhuset, Karolinska Institutet, Stockholm, Sweden.|Sachs' Children and Youth Hospital, Södersjukhuset, Stockholm, Sweden.
authors.forename: J
authors.initials: J
authors.lastname: Brandström
authors.affiliation: Department of Medicine, Clinical Immunology and Allergy Unit, Karolinska Institutet, and Hospital, Stockholm, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Nopp
authors.affiliation: Department of Medicine, Clinical Immunology and Allergy Unit, Karolinska Institutet, and Hospital, Stockholm, Sweden.
authors.forename: S G O
authors.initials: SG
authors.lastname: Johansson
authors.affiliation: Department of Clinical Science and Education, Södersjukhuset, Karolinska Institutet, Stockholm, Sweden.|Sachs' Children and Youth Hospital, Södersjukhuset, Stockholm, Sweden.
authors.forename: G
authors.initials: G
authors.lastname: Lilja
authors.affiliation: Department of Clinical Science and Education, Södersjukhuset, Karolinska Institutet, Stockholm, Sweden.|Sachs' Children and Youth Hospital, Södersjukhuset, Stockholm, Sweden.
authors.forename: A-C
authors.initials: AC
authors.lastname: Sundqvist
authors.affiliation: Thermo Fisher Scientific, Uppsala, Sweden.|Department of Women's and Children's Health, Uppsala University, Uppsala, Sweden.
authors.forename: M P
authors.initials: MP
authors.lastname: Borres
authors.affiliation: Department of Clinical Science and Education, Södersjukhuset, Karolinska Institutet, Stockholm, Sweden.|Sachs' Children and Youth Hospital, Södersjukhuset, Stockholm, Sweden.
authors.forename: C
authors.initials: C
authors.lastname: Nilsson
mesh_terms: D000293:Adolescent; D000485:Allergens / Q000276:immunology*; D001491:Basophils / Q000276:immunology*; D002648:Child; D031211:Corylus; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology*; D008297:Male; D021184:Nut Hypersensitivity / Q000175:diagnosis* / Q000276:immunology
chemical_list: D000485:Allergens; D007073:Immunoglobulin E
keywords: CD-sens; IgE antibody; basophils; flow cytometry; molecular allergology; oral food challenge; tryptase