title: Cross-reactive LTP sensitization in food-dependent exercise-induced urticaria/anaphylaxis: a pilot study of a component-resolved and in vitro depletion approach.
abstract: BACKGROUND
  Challenge tests for food-dependent exercise-induced anaphylaxis (FDEIA) carry some risk and have a high rate of false negatives. Our aim was to explore the usefulness of an in vitro immunodepletion assay and an allergen microarray test in the identification of IgE-mediated cross-reactive food allergens in patients with suspected FDEIA or food-dependent exercise-induced urticaria and panallergen sensitization.
  
  
  METHODS
  Three patients with a history of food dependent exercise induced urticaria/anaphylaxis and food panallergen sensitization in whom a food-exercise challenge was not feasible were selected: a 25-year-old man with cholinergic urticaria who experienced generalized urticaria and angioedema during a soccer match after drinking a peach-based soft drink; a 19-year-old woman with allergic rhinitis and controlled asthma who experienced anaphylactic shock while playing soccer, having eaten walnuts in the previous 90 min; and a 57-year-old man with baker's asthma who experienced four episodes of anaphylaxis during exercise after ingesting wheat-containing food. All individuals underwent a diagnostic work-up with skin prick tests, specific IgE (sIgE) and ImmunoCAP ISAC test. For the in vitro immunodepletion procedure, patients' serum was pre-incubated with the suspected native allergen (peach, walnut, or wheat) in solid phase (ImmunoCAP). The eluted serum, containing unbound IgE, was collected and samples were re-tested using Immunocap ISAC 112 and compared with baseline results.
  
  
  RESULTS
  All individuals were sensitized to lipid transfer proteins. The first patient was sensitized to Pru p 3, Cor a 8, Jug r 3, and Ara h 9; after pre-incubation with peach there was 100% depletion of sIgE to all components. The second patient was sensitized to Pru p 3, Cor a 8, Jug r 3, and Ara h 9; immunodepletion with walnut depleted sIgE to Ara h 9 by 67%, Pru p 3 and Pla a 3 (60%), Art v 3 (75%), Jug r 3 (88%), and Cor a 8 (100%). The third patient was sensitized to Pru p 3, Jug r 3, Ara h 9, and Tri a 14; immunodepletion with wheat depleted Tri a 14 only (100%).
  
  
  CONCLUSIONS
  In vitro immunodepletion might be a useful diagnostic tool in food dependent exercise induced urticaria/anaphylaxis with panallergen sensitization, particularly for identifying the culprit allergen and guiding dietary elimination recommendations.
authors.affiliation: Serviço de Imunoalergologia, Centro Hospitalar São João, Porto, Portugal ; Laboratory of Immunology, Basic and Clinical Immunology Unit, Faculty of Medicine, Porto University, Porto, Portugal.
authors.forename: Diana Margarida Gonçalves Solha Pereira
authors.identifier: 0000-0002-0656-7206
authors.initials: DM
authors.lastname: da Silva
authors.affiliation: Unidade de Imunoalergologia, Unidade Local de Saúde do Alto Minho, Viana Do Castelo, Portugal.
authors.forename: Teresa Maria Silva
authors.initials: TM
authors.lastname: Vieira
authors.affiliation: Laboratory of Immunology, Basic and Clinical Immunology Unit, Faculty of Medicine, Porto University, Porto, Portugal ; Department of Clinical Pathology, Centro Hospitalar São João, Porto, Portugal.
authors.forename: Ana Maria Alves
authors.initials: AM
authors.lastname: Pereira
authors.affiliation: Serviço de Imunoalergologia, Centro Hospitalar São João, Porto, Portugal ; Laboratory of Immunology, Basic and Clinical Immunology Unit, Faculty of Medicine, Porto University, Porto, Portugal ; ISPUP-EPIUnit, Universidade do Porto, Porto, Portugal.
authors.forename: André Miguel Afonso
authors.initials: AM
authors.lastname: de Sousa Moreira
authors.affiliation: Serviço de Imunoalergologia, Centro Hospitalar São João, Porto, Portugal ; Laboratory of Immunology, Basic and Clinical Immunology Unit, Faculty of Medicine, Porto University, Porto, Portugal ; Unidade de Imunoalergologia, Unidade Local de Saúde do Alto Minho, Viana Do Castelo, Portugal ; Department of Clinical Pathology, Centro Hospitalar São João, Porto, Portugal ; CINTESIS and Biostatistics and Medical Informatics, Faculty of Medicine, University of Porto, Porto, Portugal.
authors.forename: José Luís Dias
authors.initials: JL
authors.lastname: Delgado
keywords: Depletion; Food-dependent exercise-induced anaphylaxis; Immunodepletion; In-vitro diagnosis; Lipid transfer proteins; Urticaria