title: Dissection of immunoglobulin E and T lymphocyte reactivity of isoforms of the major birch pollen allergen Bet v 1: potential use of hypoallergenic isoforms for immunotherapy.
abstract: We dissected the T cell activation potency and the immunoglobulin (Ig) E-binding properties (allergenicity) of nine isoforms of Bet v 1 (Bet v 1a-Bet v 1l), the major birch pollen allergen. Immunoblot experiments showed that Bet v 1 isoforms differ in their ability to bind IgE from birch pollen-allergic patients. All patients tested displayed similar IgE-binding patterns toward each particular isoform. Based on these experiments, we grouped Bet v 1 isoforms in three classes: molecules with high IgE-binding activity (isoforms a, e, and j), intermediate IgE-binding (isoforms b, c, and f), and low/no IgE-binding activity (isoforms d, g, and 1). Bet v 1a, a recombinant isoform selected from a cDNA expression library using IgE immunoscreening exhibited the highest IgE-binding activity. Isoforms a, b, d, e, and 1 were chosen as representatives from the three classes for experimentation. The potency of each isoallergen to activate T lymphocytes from birch pollen-allergic patients was assayed using peripheral blood mononuclear cells, allergen-specific T cell lines, and peptide-mapped allergen-specific T cell clones. Among the patients, some displayed a broad range of T cell-recognition patterns for Bet v 1 isoforms whereas others seemed to be restricted to particular isoforms. In spite of this variability, the highest scores for T cell proliferative responses were observed with isoform d (low IgE binder), followed by b, 1, e, and a. In vivo (skin prick) tests showed that the potency of isoforms d and 1 to induce typical urticarial type 1 reactions in Bet v 1-allergic individuals was significantly lower than for isoforms a, b, and e. Taken together, our results indicate that hypoallergenic Bet v 1 isoforms are potent activators of allergen-specific T lymphocytes, and Bet v 1 isoforms with high in vitro IgE-binding activity and in vivo allergenicity can display low T cell antigenicity. Based on these findings, we propose a novel approach for immunotherapy of type I allergies: a treatment with high doses of hypoallergenic isoforms or recombinant variants of atopic allergens. We proceed on the assumption that this measure would modulate the quality of the T helper cell response to allergens in vivo. The therapy form would additionally implicate a reduced risk of anaphylactic side effects.
authors.affiliation: Institut für Genetik und Allg. Biologie, Universität Salzburg, Austria.
authors.forename: F
authors.initials: F
authors.lastname: Ferreira
authors.forename: K
authors.initials: K
authors.lastname: Hirtenlehner
authors.forename: A
authors.initials: A
authors.lastname: Jilek
authors.forename: J
authors.initials: J
authors.lastname: Godnik-Cvar
authors.forename: H
authors.initials: H
authors.lastname: Breiteneder
authors.forename: R
authors.initials: R
authors.lastname: Grimm
authors.forename: K
authors.initials: K
authors.lastname: Hoffmann-Sommergruber
authors.forename: O
authors.initials: O
authors.lastname: Scheiner
authors.forename: D
authors.initials: D
authors.lastname: Kraft
authors.forename: M
authors.initials: M
authors.lastname: Breitenbach
authors.forename: H J
authors.initials: HJ
authors.lastname: Rheinberger
authors.forename: C
authors.initials: C
authors.lastname: Ebner
mesh_terms: D000485:Allergens / Q000737:chemistry / Q000276:immunology* / Q000627:therapeutic use; D000595:Amino Acid Sequence; D052179:Antigens, Plant; D001483:Base Sequence; D002999:Clone Cells; D003001:Cloning, Molecular; D004591:Electrophoresis, Polyacrylamide Gel; D000939:Epitopes; D006801:Humans; D006967:Hypersensitivity / Q000628:therapy*; D015151:Immunoblotting; D007167:Immunotherapy / Q000379:methods; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000627:therapeutic use; D011058:Pollen / Q000737:chemistry / Q000276:immunology*; D011994:Recombinant Proteins / Q000276:immunology / Q000302:isolation & purification / Q000627:therapeutic use; D017421:Sequence Analysis; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D000485:Allergens; D052179:Antigens, Plant; D000939:Epitopes; D010940:Plant Proteins; D011994:Recombinant Proteins; C061312:Bet v 1 allergen, Betula