title: Cor a 1-reactive T cells and IgE are predominantly cross-reactive to Bet v 1 in patients with birch pollen-associated food allergy to hazelnut.
abstract: BACKGROUND
  IgE- and T-cell cross-reactivity contribute to the birch pollen-food syndrome.
  
  
  OBJECTIVE
  We performed a comprehensive analysis of T-cell cross-reactivity in primary cell cultures, facilitating the identification of allergen-specific T-cell subpopulations from individual patients.
  
  
  METHODS
  Patients with birch pollen allergy and associated food allergy to hazelnuts, carrots, or both were analyzed for IgE cross-reactivity, T-cell responses, and T-cell cross-reactivity to recombinant Bet v 1.0101 (Bet v 1; birch), Cor a 1.0401 (Cor a 1; hazelnut), and Dau c 1.0104 (Dau c 1; carrot). A novel flow cytometry-based method using a 2-step staining process with fluorescent dyes was established to identify subpopulations of cross-reactive T cells.
  
  
  RESULTS
  IgE-binding inhibition tests of individual sera revealed that the vast majority of Cor a 1-reactive IgE was cross-reactive to Bet v 1, whereas Bet v 1-reactive IgE was only partially inhibited by preincubation with Cor a 1. Primary stimulation of T cells with Bet v 1 or Cor a 1 resulted in a significant increase in specific responses to Cor a 1 or Bet v 1 after secondary stimulation, respectively, indicating T-cell cross-reactivity between birch and hazelnut allergens in all patients of the study cohort. Preactivation with Dau c 1 induced less pronounced effects. A novel flow cytometry-based proliferation assay identified a predominant Cor a 1/Bet v 1-cross-reactive T-cell subpopulation within highly Bet v 1/Cor a 1-responsive T cells.
  
  
  CONCLUSIONS
  Analysis of primary allergen-specific T cells combined with flow cytometry-based proliferation assays facilitates investigation of allergen-specific T-cell subpopulations in subjects and might be helpful to evaluate the effect of birch-specific immunotherapy on pollen-associated food allergies.
authors.affiliation: Department of Dermatology, University Medical Center of the Johannes Gutenberg-Universität, Mainz, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Hofmann
authors.forename: Stephan
authors.initials: S
authors.lastname: Scheurer
authors.forename: Kathrin
authors.initials: K
authors.lastname: Rost
authors.forename: Edith
authors.initials: E
authors.lastname: Graulich
authors.forename: Annette
authors.initials: A
authors.lastname: Jamin
authors.forename: Kay
authors.initials: K
authors.lastname: Foetisch
authors.forename: Joachim
authors.initials: J
authors.lastname: Saloga
authors.forename: Stefan
authors.initials: S
authors.lastname: Vieths
authors.forename: Kerstin
authors.initials: K
authors.lastname: Steinbrink
authors.forename: Henric S
authors.initials: HS
authors.lastname: Adler
mesh_terms: D000328:Adult; D000485:Allergens / Q000009:adverse effects / Q000276:immunology; D052179:Antigens, Plant / Q000009:adverse effects / Q000276:immunology / Q000378:metabolism; D029662:Betula / Q000009:adverse effects / Q000276:immunology*; D016022:Case-Control Studies; D002478:Cells, Cultured; D031211:Corylus / Q000009:adverse effects / Q000276:immunology*; D003429:Cross Reactions; D018552:Daucus carota / Q000009:adverse effects / Q000276:immunology; D005260:Female; D005512:Food Hypersensitivity / Q000209:etiology* / Q000276:immunology*; D006801:Humans; D007073:Immunoglobulin E / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010940:Plant Proteins / Q000009:adverse effects* / Q000276:immunology* / Q000378:metabolism; D011058:Pollen / Q000009:adverse effects / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D055815:Young Adult
chemical_list: D000485:Allergens; D052179:Antigens, Plant; C061277:Cor a I protein, hazel; D010940:Plant Proteins; C061312:Bet v 1 allergen, Betula; D007073:Immunoglobulin E