Major feline allergen Fel d 1 (Fel d 1) (Fel d 1)

Major feline allergen Fel d 1 is a secretoglobin protein complex and the primary allergen produced by domestic cats (Felis catus), responsible for approximately 60-90% of the total allergenic activity in cat-sensitized individuals [1, 7]. It is a 35-38 kDa tetrameric glycoprotein composed of two non-covalently linked heterodimers, each consisting of two polypeptide chains (Chain 1 and Chain 2) [1, 3]. While its endogenous biological function in felines is not fully understood, it is hypothesized to be involved in pheromone transport, lipid binding, or skin protection [1, 9]. In humans, Fel d 1 triggers an IgE-mediated immune response upon inhalation, leading to symptoms of allergic rhinitis, conjunctivitis, and asthma [3, 10]. Therapeutic strategies targeting Fel d 1 include monoclonal antibodies like REGN1908-1909 that neutralize the allergen, peptide-based immunotherapies to induce T-cell tolerance, and dietary interventions for cats using anti-Fel d 1 IgY to reduce the allergen load at the source [10, 15, 16].

Other names

Cat allergen 1Ag4Fel d 1-related proteinMajor cat allergen

Neutralization of the allergen to prevent IgE-mediated mast cell and basophil degranulation; induction of allergen-specific IgG4 blocking antibodies; and promotion of T-cell tolerance.