title: An unfolded variant of the major peanut allergen Ara h 2 with decreased anaphylactic potential.
abstract: BACKGROUND
  Peanut allergy causes severe type 1 hypersensitivity reactions and conventional immunotherapy against peanut allergy is associated with a high risk of anaphylaxis.
  
  
  OBJECTIVE
  Our current study reports proof of concept experiments on the safety of a stably denatured variant of the major peanut allergen Ara h 2 for immunotherapy. We determined the impact of structure loss of Ara h 2 on its IgE binding and basophil degranulation capacity, T cell reactivity as well as anaphylactic potential.
  
  
  METHODS
  The secondary structure of untreated and reduced/alkylated Ara h 2 variants was determined by circular dichroism spectroscopy. We addressed human patient IgE binding to Ara h 2 by ELISA and Western blot experiments. RBL-SX38 cells were used to test the degranulation induced by untreated and reduced/alkylated Ara h 2. We assessed the anaphylactic potential of Ara h 2 variants by challenge of sensitized BALB/c mice. T cell reactivity was investigated using human Ara h 2-specific T cell lines and splenocytes isolated from sensitized mice.
  
  
  RESULTS
  Reduction/alkylation of Ara h 2 caused a decrease in IgE binding capacity, basophil degranulation and anaphylactic potential in vivo. However, the human T cell response to reduced/alkylated and untreated Ara h 2 was comparable. Mouse splenocytes showed higher metabolic activity upon stimulation with reduced/alkylated Ara h 2 and released similar IL-4, IL-13 and IFNγ levels upon treatment with either Ara h 2 variant.
  
  
  CONCLUSIONS
  Reduced/alkylated Ara h 2 might be a safer alternative than native Ara h 2 for immunotherapeutic treatment of peanut allergic patients.
authors.affiliation: Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria.
authors.forename: P
authors.initials: P
authors.lastname: Starkl
authors.forename: F
authors.initials: F
authors.lastname: Felix
authors.forename: D
authors.initials: D
authors.lastname: Krishnamurthy
authors.forename: C
authors.initials: C
authors.lastname: Stremnitzer
authors.forename: F
authors.initials: F
authors.lastname: Roth-Walter
authors.forename: S R
authors.initials: SR
authors.lastname: Prickett
authors.forename: A L
authors.initials: AL
authors.lastname: Voskamp
authors.forename: A
authors.initials: A
authors.lastname: Willensdorfer
authors.forename: K
authors.initials: K
authors.lastname: Szalai
authors.forename: M
authors.initials: M
authors.lastname: Weichselbaumer
authors.forename: R E
authors.initials: RE
authors.lastname: O'Hehir
authors.forename: E
authors.initials: E
authors.lastname: Jensen-Jarolim
mesh_terms: D055516:2S Albumins, Plant / Q000009:adverse effects / Q000737:chemistry* / Q000627:therapeutic use*; D000293:Adolescent; D000478:Alkylation; D000707:Anaphylaxis / Q000517:prevention & control*; D000818:Animals; D052179:Antigens, Plant / Q000009:adverse effects / Q000737:chemistry* / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D002942:Circular Dichroism; D003888:Desensitization, Immunologic; D005260:Female; D006023:Glycoproteins / Q000009:adverse effects / Q000737:chemistry* / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D051379:Mice; D021183:Peanut Hypersensitivity / Q000276:immunology / Q000517:prevention & control / Q000628:therapy*; D058767:Protein Unfolding; D013057:Spectrum Analysis / Q000379:methods; D016896:Treatment Outcome
chemical_list: D055516:2S Albumins, Plant; D052179:Antigens, Plant; C500890:Ara h 2 allergen, Arachis hypogaea; D006023:Glycoproteins