title: In vivo and T cell cross-reactivity between walnut, cashew and peanut.
abstract: BACKGROUND
  Examination of IgE cross-reactivity among nuts has been limited to in vitro experiments. Cross-reactivity studies of nuts at the T cell level are difficult to interpret because of the inability to determine which cellular responses are from a true sensitization and which are due to cross-reactivity. Using a mouse model in which the sensitizing nuts are controlled may provide novel methods to investigate in vivo and T cell cross-reactivity.
  
  
  METHODS
  C3H/HeJ mice were sensitized by intraperitoneal injection of cashew alone (monosensitized mice), or cashew plus walnut, utilizing alum as an adjuvant. Both groups underwent challenges to cashew, walnut and peanut, with subsequent monitoring of anaphylactic reactions. Anaphylactic antibodies were quantified by ELISA, and protein allergens were identified by Western blotting. Cellular responses were studied via splenocyte proliferation assay and measurement of secreted cytokines.
  
  
  RESULTS
  The monosensitized mice reacted to cashew and walnut during challenges, with significantly weaker reactions induced on challenge with peanut. Cross-reactive IgE to walnut and peanut were detected by ELISA, and the cross-reactive allergens were identified as vicilin proteins. In cellular assays, splenocytes from the monosensitized mice proliferated and produced IL-4 and IL-5 in response to cashew, walnut and peanut. The cashew- plus walnut-sensitized mice experienced stronger clinical reactions to walnut, recognized additional walnut allergens and secreted significantly more IL-4 and IL-5 in walnut-stimulated splenocyte assays compared to the monosensitized mice.
  
  
  CONCLUSIONS
  Cross-reactivity in vivo was found between cashew and walnut, while cross-reactivity among cashew, walnut and peanut was demonstrated at the T cell level.
authors.affiliation: Department of Pediatrics, Division of Pediatric Allergy and Immunology, Duke University Medical Center, Durham, NC 27710, USA. michael.kulis@duke.edu
authors.forename: Michael
authors.initials: M
authors.lastname: Kulis
authors.forename: Laurent
authors.initials: L
authors.lastname: Pons
authors.forename: A Wesley
authors.initials: AW
authors.lastname: Burks
mesh_terms: D000485:Allergens / Q000737:chemistry / Q000276:immunology; D031021:Anacardium / Q000009:adverse effects / Q000276:immunology*; D000818:Animals; D010367:Arachis / Q000009:adverse effects / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology; D003429:Cross Reactions; D004195:Disease Models, Animal; D005260:Female; D005512:Food Hypersensitivity / Q000209:etiology* / Q000276:immunology*; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology; D007074:Immunoglobulin G / Q000276:immunology; D031324:Juglans / Q000009:adverse effects / Q000276:immunology*; D051379:Mice; D008809:Mice, Inbred C3H; D010940:Plant Proteins; D055314:Seed Storage Proteins / Q000737:chemistry / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D000485:Allergens; D007074:Immunoglobulin G; D010940:Plant Proteins; D055314:Seed Storage Proteins; D007073:Immunoglobulin E; C015575:vicilin protein, plant