Chimeric Human Fcγ-Allergen Fusion Proteins in the Prevention of Allergy

Allergic responses are strongly associated with Th2-type immune responses, and modulation of the skewed Th2 response toward a more balanced response is the major goal of allergen immunotherapy (IT) in allergic disorders. To achieve this goal, several approaches have been tested. The authors previously showed that a human immunoglobulin (Ig) Fcγ-Fcɛ fusion protein (GE2) that directly cross-links FcɛRI and FcγRIIb on human mast cells and basophils was able to inhibit degranulation, and they reasoned that human gamma-allergen fusion protein would achieve a similar inhibitory effect in an allergen-specific fashion while preserving the immunogenicity of the allergen component. Therefore, the authors constructed and developed a human-cat chimeric fusion protein composed of the human Fcγ1 and the cat allergen Fel d1 (Felis domesticus) for cat allergen-specific IT. This article summarizes the therapeutic features and potential of this novel fusion protein for allergic IT.