title: Natural clinical tolerance to peanut in African patients is caused by poor allergenic activity of peanut IgE.
abstract: BACKGROUND
  In Africa, peanuts are frequently consumed, but severe allergic reactions are rare. We investigated immunological patterns of clinical tolerance to peanut in peanut-sensitized but asymptomatic patients from central Africa compared to peanut-allergic and peanut-sensitized but asymptomatic patients from Sweden.
  
  
  METHODS
  Sera from allergic patients (n = 54) from Zimbabwe sensitized to peanut but without allergic symptoms to peanut, and sera from peanut-allergic (n = 25) and peanut-sensitized but asymptomatic (n = 25) patients from Sweden were analyzed toward peanut allergen components (Ara h 1-3, 6, 8-9) and other allergen molecules from important allergen sources using microarray. IgE to Ara h 2 peptide epitopes was analyzed, and allergenic activity was assessed by basophil activation assay.
  
  
  RESULTS
  Forty-six percent of the African and all peanut-allergic Swedish patients showed IgE toward one of the highly allergenic peanut allergens (Ara h 1-3, 6, 9). However, 48% of the African patients had IgE to cross-reactive carbohydrate determinants (CCDs) with low allergenic activity and 60% of the Swedish asymptomatic patients had IgE against the PR protein Ara h 8. IgG and IgG4 specificities and levels could not discriminate between the African asymptomatic and Swedish peanut-allergic patients. Asymptomatic patients almost lacked IgE to Ara h 2 peptides, which were recognized by peanut-allergic patients. Peanut IgE from peanut asymptomatic patients showed poor allergenic activity compared with IgE from peanut-allergic patients.
  
  
  CONCLUSIONS
  Natural clinical tolerance to peanut in the African patients can be caused by IgE to low allergenic peanut components and by poor allergenic activity of peanut-specific IgE.
authors: Division of Immunopathology, Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.
authors: E
authors: E
authors: Wollmann
authors: Department of Medicine Solna, Clinical Immunology and Allergy Unit, Karolinska Institutet and University Hospital, Stockholm, Sweden.|Center for Inflammatory Diseases, Karolinska Institutet, Stockholm, Sweden.
authors: C
authors: C
authors: Hamsten
authors: University of Zimbabwe Medical School, Harare, Zimbabwe.
authors: E
authors: E
authors: Sibanda
authors: Division of Immunopathology, Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.
authors: M
authors: M
authors: Ochome
authors: Division of Immunopathology, Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.
authors: M
authors: M
authors: Focke-Tejkl
authors: Department of Medicine Solna, Clinical Immunology and Allergy Unit, Karolinska Institutet and University Hospital, Stockholm, Sweden.|Astrid Lindgren Children's Hospital, Stockholm, Sweden.
authors: A
authors: A
authors: Asarnoj
authors: Thermo Fisher Scientific ImmunoDiagnostics, Uppsala, Sweden.
authors: A
authors: A
authors: Önell
authors: Department of Pediatrics, Sachs' Children's Hospital, Stockholm, Sweden.
authors: G
authors: G
authors: Lilja
authors: Division of Immunopathology, Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.
authors: D
authors: D
authors: Gallerano
authors: Division of Immunopathology, Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.
authors: C
authors: C
authors: Lupinek
authors: Department of Molecular Biology, University of Salzburg, Salzburg, Austria.
authors: T
authors: T
authors: Thalhamer
authors: Department of Molecular Biology, University of Salzburg, Salzburg, Austria.
authors: R
authors: R
authors: Weiss
authors: Department of Molecular Biology, University of Salzburg, Salzburg, Austria.
authors: J
authors: J
authors: Thalhamer
authors: Department of Pediatrics, Sachs' Children's Hospital, Stockholm, Sweden.|Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
authors: M
authors: M
authors: Wickman
authors: Division of Immunopathology, Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.
authors: R
authors: R
authors: Valenta
authors: Department of Medicine Solna, Clinical Immunology and Allergy Unit, Karolinska Institutet and University Hospital, Stockholm, Sweden.
authors: M
authors: M
authors: van Hage
mesh_terms: D055516:2S Albumins, Plant / Q000276:immunology; D000293:Adolescent; D000328:Adult; D000485:Allergens / Q000276:immunology*; D052179:Antigens, Plant / Q000276:immunology*; D010367:Arachis / Q000276:immunology*; D058070:Asymptomatic Diseases; D044383:Black People; D002648:Child; D002675:Child, Preschool; D005260:Female; D006023:Glycoproteins / Q000276:immunology; D006801:Humans; D007108:Immune Tolerance / Q000276:immunology*; D007073:Immunoglobulin E / Q000276:immunology*; D007074:Immunoglobulin G / Q000276:immunology; D007223:Infant; D008297:Male; D008565:Membrane Proteins; D008875:Middle Aged; D021183:Peanut Hypersensitivity / Q000276:immunology*; D010940:Plant Proteins / Q000276:immunology; D012882:Skin Tests; D013548:Sweden; D044465:White People; D055815:Young Adult; D015030:Zimbabwe
chemical_list: D055516:2S Albumins, Plant; D000485:Allergens; D052179:Antigens, Plant; C500889:Ara h 1 protein, Arachis hypogaea; C500890:Ara h 2 allergen, Arachis hypogaea; C549941:Ara h 3 allergen, Arachis hypogea; C492737:Ara h 6 allergen, Arachis hypogaea; C000594056:Ara h 8 allergen, peanut; C544631:Ara h 9 allergen, peanut; D006023:Glycoproteins; D007074:Immunoglobulin G; D008565:Membrane Proteins; D010940:Plant Proteins; D007073:Immunoglobulin E
keywords: Africa; allergen component; allergy; peanut; tolerance