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.