title: Glutathione-S-transferase: a minor allergen in birch pollen due to limited release from hydrated pollen.
abstract: BACKGROUND
  Recently, a protein homologous to glutathione-S-transferases (GST) was detected in prominent amounts in birch pollen by proteomic profiling. As members of the GST family are relevant allergens in mites, cockroach and fungi we investigated the allergenic relevance of GST from birch (bGST).
  
  
  METHODS
  bGST was expressed in Escherichia coli, purified and characterized by mass spectrometry. Sera from 217 birch pollen-allergic patients were tested for IgE-reactivity to bGST by ELISA. The mediator-releasing activity of bGST was analysed with IgE-loaded rat basophil leukaemia cells (RBL) expressing human FcεRI. BALB/c mice were immunized with bGST or Bet v 1. Antibody and T cell responses to either protein were assessed. IgE-cross-reactivity between bGST with GST from house dust mite, Der p 8, was studied with murine and human sera in ELISA. The release kinetics of bGST and Bet v 1 from birch pollen were assessed in water, simulated lung fluid, 0.9% NaCl and PBS. Eluted proteins were quantified by ELISA and analysed by immunoblotting.
  
  
  RESULTS
  Only 13% of 217 birch pollen-allergic patients showed IgE-reactivity to bGST. In RBL assays bGST induced mediator release. Immunization of mice with bGST induced specific IgE and a Th2-dominated cellular immune response comparably to immunization with Bet v 1. bGST did not cross-react with Der p 8. In contrast to Bet v 1, only low amounts of bGST were released from pollen grains upon incubation in water and the different physiological solutions.
  
  
  CONCLUSIONS
  Although bGST is abundant in birch pollen, immunogenic in mice and able to induce mediator release from effector cells passively loaded with specific IgE, it is a minor allergen for birch pollen-allergic patients. We refer this discrepancy to its limited release from hydrated pollen. Hence, bGST is an example demonstrating that allergenicity depends mainly on rapid elution from airborne particles.
authors.affiliation: Christian Doppler Laboratory for Immunomodulation, Medical University of Vienna, Vienna, Austria; Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria.
authors.forename: Stephan
authors.initials: S
authors.lastname: Deifl
authors.affiliation: Christian Doppler Laboratory for Immunomodulation, Medical University of Vienna, Vienna, Austria; Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria.
authors.forename: Christian
authors.initials: C
authors.lastname: Zwicker
authors.affiliation: Christian Doppler Laboratory for Allergy Diagnosis and Therapy, University of Salzburg, Salzburg, Austria.
authors.forename: Eva
authors.initials: E
authors.lastname: Vejvar
authors.affiliation: Christian Doppler Laboratory for Immunomodulation, Medical University of Vienna, Vienna, Austria; Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria.
authors.forename: Claudia
authors.initials: C
authors.lastname: Kitzmüller
authors.affiliation: Christian Doppler Laboratory for Allergy Diagnosis and Therapy, University of Salzburg, Salzburg, Austria.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Gadermaier
authors.affiliation: Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria.
authors.forename: Birgit
authors.initials: B
authors.lastname: Nagl
authors.affiliation: Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria.
authors.forename: Susanne
authors.initials: S
authors.lastname: Vrtala
authors.affiliation: Department of Molecular Biology, University of Salzburg, Salzburg, Austria.
authors.forename: Peter
authors.initials: P
authors.lastname: Briza
authors.affiliation: Institute of Immunology, Medical University of Vienna, Vienna, Austria.
authors.forename: Gerhard J
authors.initials: GJ
authors.lastname: Zlabinger
authors.affiliation: Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria.
authors.forename: Beatrice
authors.initials: B
authors.lastname: Jahn-Schmid
authors.affiliation: Christian Doppler Laboratory for Allergy Diagnosis and Therapy, University of Salzburg, Salzburg, Austria.
authors.forename: Fatima
authors.initials: F
authors.lastname: Ferreira
authors.affiliation: Christian Doppler Laboratory for Immunomodulation, Medical University of Vienna, Vienna, Austria; Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria.
authors.forename: Barbara
authors.initials: B
authors.lastname: Bohle
mesh_terms: D000485:Allergens / Q000737:chemistry / Q000276:immunology*; D000595:Amino Acid Sequence; D000818:Animals; D000917:Antibody Formation / Q000276:immunology; D029662:Betula / Q000201:enzymology* / Q000276:immunology*; D002460:Cell Line; D003429:Cross Reactions / Q000276:immunology; D005260:Female; D005982:Glutathione Transferase / Q000737:chemistry / Q000276:immunology*; D006801:Humans; D007109:Immunity; D007700:Kinetics; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D011058:Pollen / Q000276:immunology*; D039981:Pyroglyphidae / Q000201:enzymology; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000276:immunology; D014867:Water / Q000737:chemistry*
chemical_list: D000485:Allergens; D011994:Recombinant Proteins; D014867:Water; D005982:Glutathione Transferase