title: IgE epitope proximity determines immune complex shape and effector cell activation capacity.
abstract: IgE-allergen complexes induce mast cell and basophil activation and thus immediate allergic inflammation. They are also important for IgE-facilitated allergen presentation to T cells by antigen-presenting cells.
  
  
  
  To investigate whether the proximity of IgE binding sites on an allergen affects immune complex shape and subsequent effector cell activation in vitro and in vivo.
  
  
  
  We constructed artificial allergens by grafting IgE epitopes in different numbers and proximity onto a scaffold protein. The shape of immune complexes formed between artificial allergens and the corresponding IgE was studied by negative-stain electron microscopy. Allergenic activity was determined using basophil activation assays. Mice were primed with IgE, followed by injection of artificial allergens to evaluate their in vivo allergenic activity. Severity of systemic anaphylaxis was measured by changes in body temperature.
  
  
  
  We could demonstrate simultaneous binding of 4 IgE antibodies in close vicinity to each other. The proximity of IgE binding sites on allergens influenced the shape of the resulting immune complexes and the magnitude of effector cell activation and in vivo inflammation.
  
  
  
  Our results demonstrate that the proximity of IgE epitopes on an allergen affects its allergenic activity. We thus identified a novel mechanism by which IgE-allergen complexes regulate allergic inflammation. This mechanism should be important for allergy and other immune complex-mediated diseases.
authors.affiliation: Division of Immunopathology, Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology & Immunology, Medical University of Vienna, Vienna, Austria.
authors.forename: Anna
authors.initials: A
authors.lastname: Gieras
authors.affiliation: Division of Immunopathology, Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology & Immunology, Medical University of Vienna, Vienna, Austria.
authors.forename: Birgit
authors.initials: B
authors.lastname: Linhart
authors.affiliation: Department of Biological Science and the Institute of Molecular Biophysics, The Florida State University, Tallahassee, Fla.
authors.forename: Kenneth H
authors.initials: KH
authors.lastname: Roux
authors.affiliation: Department of Biological Science and the Institute of Molecular Biophysics, The Florida State University, Tallahassee, Fla.
authors.forename: Moumita
authors.initials: M
authors.lastname: Dutta
authors.affiliation: Department of Medicine, Cincinnati Veterans Affairs Medical Center, Cincinnati, Ohio; Division of Immunology, Allergy and Rheumatology, University of Cincinnati College of Medicine, Cincinnati, Ohio; Division of Cellular and Immunobiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.
authors.forename: Marat
authors.initials: M
authors.lastname: Khodoun
authors.affiliation: Division of Structural Biology, Institute of Molecular Biosciences, Karl Franzens University of Graz, Graz, Austria.
authors.forename: Domen
authors.initials: D
authors.lastname: Zafred
authors.affiliation: Division of Immunopathology, Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology & Immunology, Medical University of Vienna, Vienna, Austria.
authors.forename: Clarissa R
authors.initials: CR
authors.lastname: Cabauatan
authors.affiliation: Division of Immunopathology, Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology & Immunology, Medical University of Vienna, Vienna, Austria.
authors.forename: Christian
authors.initials: C
authors.lastname: Lupinek
authors.affiliation: Division of Immunopathology, Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology & Immunology, Medical University of Vienna, Vienna, Austria.
authors.forename: Milena
authors.initials: M
authors.lastname: Weber
authors.affiliation: Division of Immunopathology, Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology & Immunology, Medical University of Vienna, Vienna, Austria.
authors.forename: Margarete
authors.initials: M
authors.lastname: Focke-Tejkl
authors.affiliation: Division of Structural Biology, Institute of Molecular Biosciences, Karl Franzens University of Graz, Graz, Austria.
authors.forename: Walter
authors.initials: W
authors.lastname: Keller
authors.affiliation: Department of Medicine, Cincinnati Veterans Affairs Medical Center, Cincinnati, Ohio; Division of Immunology, Allergy and Rheumatology, University of Cincinnati College of Medicine, Cincinnati, Ohio; Division of Cellular and Immunobiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.
authors.forename: Fred D
authors.initials: FD
authors.lastname: Finkelman
authors.affiliation: Division of Immunopathology, Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology & Immunology, Medical University of Vienna, Vienna, Austria. Electronic address: rudolf.valenta@meduniwien.ac.at.
authors.forename: Rudolf
authors.initials: R
authors.lastname: Valenta
mesh_terms: D000485:Allergens / Q000235:genetics / Q000276:immunology; D000707:Anaphylaxis / Q000276:immunology; D000818:Animals; D000936:Antigen-Antibody Complex / Q000276:immunology*; D000939:Epitopes / Q000276:immunology*; D007073:Immunoglobulin E / Q000276:immunology*; D008807:Mice, Inbred BALB C; D009211:Myoglobin / Q000235:genetics / Q000276:immunology; D010940:Plant Proteins / Q000235:genetics / Q000276:immunology; D011994:Recombinant Proteins / Q000276:immunology
chemical_list: D000485:Allergens; D000936:Antigen-Antibody Complex; D000939:Epitopes; D009211:Myoglobin; D010940:Plant Proteins; D011994:Recombinant Proteins; C090396:PHLPI protein, Phleum pratense; D007073:Immunoglobulin E
keywords: Allergy; IgE epitope; allergen; effector cells; immune complex