Fel d 1 (major cat allergen) (Fel d 1)

Fel d 1 is a tetrameric glycoprotein (~35–39 kDa) composed of two disulfide-linked heterodimers (each of chains 1 and 2), secreted predominantly by the sebaceous, salivary, and anal glands of domestic cats[1][2][3][4][6]. It has an all alpha-helical structure and shares similarity with uteroglobin, a secretoglobin superfamily protein[1][2][4]. Fel d 1’s physiological function in cats remains unclear, but it likely binds and transports semiochemicals (pheromones, steroids, fatty acids) and may play a role in chemical communication[3][5]. In sensitive humans, Fel d 1 triggers IgE-mediated immune responses, leading to symptoms of allergic rhinitis, conjunctivitis, asthma, and sometimes systemic reactions[2][4][6]. Molecular studies have identified several IgE epitopes and ligand-binding cavities, suggesting possibilities for rational drug or vaccine design[1][3][4]. While Fel d 1-neutralizing drugs and immunotherapies are under investigation, environmental control remains a mainstay for management of cat allergy.

Other names

Major cat allergenCat dander allergenSecretoglobin family 1A memberCat allergen protein

Immunotherapy: induces immune tolerance, reducing IgE-mediated responses Monoclonal antibodies: neutralize Fel d 1 and prevent IgE cross-linking/mast cell activation