Allergies mediated by immunoglobulin E (IgE) are the most common immunological hypersensitivity diseases. The prevalence has been continuously increasing in recent decades, and more than 25% of the population is currently afected. Symptoms of allergies can be observed in the skin and respiratory and gastrointestinal tracts, and systemic manifestations include anaphylactic shock. If an allergy is not properly diagnosed and treated, it tends to progress to a severe and chronic debilitating disease. Understanding the mechanisms by which the immune system induces and controls allergic inlammation depends on knowing the structure of several allergens and identifying epitopes, which are critical for the design of new strategies for treating allergies. Strategies for immunotherapy will be reviewed. Allergen-speciic immunotherapy has been used for nearly a century and remains one of the few antigen-speciic treatments for inlammatory diseases. There is a strong rationale for improving the eicacy of allergen-speciic immunotherapy by reducing the incidence and severity of adverse reactions mediated by IgE. Approaches to address this problem, including the use of modiied allergens, synthetic peptides as vaccines, and alternative strategies for blocking IgE, will be discussed.

Ric c1, an allergenic protein from castor oil plants (Ricinus communis), is an insect α-amylase inhibitor that has become an occupational allergen. Ric c1 can cross-react with allergens from wheat, soybean, peanut, shrimp, fish, gluten, house dust, tobacco and air fungus, thereby amplifying the concern and risks caused by castor oil plants (COP) allergens. Two continuous IgE-binding epitopes were identified in Ric c1, both containing glutamic acid residues involved in IgE-binding and allergic challenges. We produced recombinant Ric c1 (rRic c1) in Escherichia coli, using primers from foliar castor oil plant DNA, and a mutant (Glu-Leu) recombinant protein (mrRic c1) in the same system using synthetic genes. rRic c1 preserved both allergenic and α-amylase inhibitory properties, and mrRic c1 drastically reduced allergenic properties. These results can help to establish meaningful relationships between structure, defence and allergenicity, important steps for producing engineered plants and developing new approaches for immunotherapy.