Blocking-Antibody Responses Pattern for Induction of Protective IgE Binding but Retains Protein Folding Modulation of Recombinant Bet v 1 Reduces Allergy Vaccine Engineering: Epitope

Human type 1 immediate allergic response symptoms are caused by mediator release from basophils and mast cells. This event is triggered by allergens aggregating preformed IgE Abs bound to the high-affinity receptor (Fc⑀RI) on these cells. Thus, the allergen/IgE interaction is crucial for the cascade leading to the allergic and anaphylactic response. Two genetically engineered forms of the white birch pollen major allergen Bet v 1 with point mutations directed at molecular surfaces have been characterized. Four and nine point mutations led to a significant reduction of the binding to human serum IgE, suggesting a mutation-induced distortion of IgE-binding B cell epitopes. In addition, the mutated allergens showed a decrease in anaphylactic potential, because histamine release from human basophils was significantly reduced. Retained ␣-carbon backbone folding pattern of the mutated allergens was indicated by x-ray diffraction analysis and circular dichroism spectroscopy. The rBet v 1 mutants were able to induce proliferation of T cell lines derived from birch pollen allergic patients. The stimulation indices were similar to the indices of nonmutated rBet v 1 and natural Bet v 1 purified from birch pollen. The ability of anti-rBet v 1 mutant specific mouse IgG serum to block binding of human serum IgE to rBet v 1 demonstrates that the engineered rBet v 1 mutants are able to induce Abs reactive with nonmodified Bet v 1. rBet v 1 mutants may constitute vaccine candidates with improved efficacy/safety profiles for safer allergy vaccination. S pecific allergy vaccination (SAV), 5 i.e., allergen-specific immunotherapy, is an effective and well-tolerated treatment for allergic disease in selected patients. Controlled studies have shown efficacy in patients with allergic rhinitis/con-junctivitis, allergic asthma, and allergic reactions from stinging insects (1, 2). Effective treatment is correlated with the use of standardized vaccines in maintenance doses containing 5–20 ␮g of major allergen for 3–5 years (3). The effect of allergy vaccination lasts at least several years after discontinuing treatment (4 –7) and prevents the development of hay fever into asthma in children (8), and thus, allergy vaccination is currently the only treatment to alter the natural course of allergic disease. Several studies addressing the mechanisms of allergy vaccination have shown effects on both innate and acquired immunolog-ical parameters (9, 10). The most pronounced serological marker of successful vaccination is a 30-to 100-fold increase in allergen-specific IgG (11, 12), whereas there is no substantial change in IgE comparing pre-and posttreatment (6). Furthermore, as …