IMMUNIZATION WITH PURIFIED NATURAL AND RECOMBINANT ALLERGENS INDUCES MOUSE IGG1 ANTIBODIES THAT RECOGNIZE SIMILAR EPITOPES AS HUMAN IGE ANDINHIBIT THE HUMAN IGE-ALLERGEN INTERACTION AND ALLERGEN-INDUCED BASOPHIL DEGRANULATION

Molecular characterization of allergens by recombinant DNA technology has made rapid progress in the recent few years. In the present study we immunized mice with aluminum hydroxide-adsorbed purified recombinan t major timothy grass pollen allergens (rPhlp 1, rPhlp 2, rPhlp 5), do g albumin, a major animal dander allergen, and proteins with low (beta -lactoglobulin) or no (ribulose diphosphate carboxylase) allergenic po tential in humans. Allergens that bind high levels of IgE in humans (P hlp 1, Phlp 5, dog albumin) induced high IgE and IgG1 levels in mice, whereas proteins with little or no allergenic activity in humans faile d to induce significant IgE and IgG1 levels in mice. Continuous immuni zation for a period of 27 wk resulted in the production of mouse IgG1 Abs that recognized recombinant allergen fragments/epitopes defined by IgE Abs of allergic patients. As a consequence, allergen-specific mou se Abs strongly inhibited human IgE binding to the allergens and suppr essed the allergen-induced histamine release from human basophils, In summary, our data indicate that 1) the allergenic potency of a protein may be related to its overall immunogenicity and 2) prolonged immuniz ation with single purified recombinant allergens induces protective Ig G Abs, The presented experimental in vivo/in vitro system allows the e valuation of Ag preparations (e.g., recombinant allergens) to be used for immunotherapy in humans.