Design and modifications of allergens for improving specific immunotherapy.

Specific immunotherapy is a clinically effective causative treatment for allergic conditions. However, the reagents used for immunotherapy are crude extracts, prepared from natural sources, and as such may cause potential life-threatening anaphylactic side effects. Our increasing knowledge of mechanisms that lead to allergy and of the mechanisms of successful immunotherapy have introduced new ideas for the treatment of allergic diseases. Techniques of biochemistry and molecular biology have made it feasible to design novel therapeutic approaches for improved and safer forms of allergen-specific immunotherapy. The purpose of this review is to examine different approaches in designing novel allergen formulations for specific immunotherapy. These include chemically modified forms of allergens, genetically modified allergens (hypoallergens), hybrid allergens and allergens bearing immunostimulatory molecules, or adjuvants, which foster Th 1 immune responses. There is great interest in newly designed allergens and their derivatives to improve the efficacy and safety of allergen immunotherapy. A better understanding of immunological mechanisms and further clinical trials utilizing new allergen formulations are needed.