Major cat allergen 1 (Fel d 1) (Fel d 1)

Major cat allergen 1, widely known as Fel d 1, is a secretoglobin protein produced primarily in the sebaceous and salivary glands of the domestic cat (Felis catus). It exists as a 35-38 kDa heterotetrameric glycoprotein composed of two identical heterodimers, each containing two polypeptide chains linked by disulfide bonds. While its precise biological function in felines is not fully understood, it is hypothesized to serve as a carrier for pheromones or other lipid ligands, or to provide protective functions for the skin and mucosa. In humans, Fel d 1 is the most potent feline allergen, responsible for inducing immunoglobulin E (IgE)-mediated allergic responses in over 90% of cat-allergic individuals. Due to its small aerodynamic size and high environmental stability, Fel d 1 remains airborne for long periods and persists on surfaces, triggering symptoms ranging from allergic rhinitis and conjunctivitis to severe asthmatic exacerbations. Therapeutic interventions include monoclonal antibodies like the REGN1908/1909 cocktail, which neutralize the allergen to prevent mast cell degranulation, as well as cat-targeted vaccines and dietary interventions designed to reduce the allergen load at the source.

Other names

Fel d 1Felis domesticus allergen 1Fel d ISecretoglobin family 1A member 2 (Chain 1)Secretoglobin family 2A member 1 (Chain 2)

Neutralization of the allergen to prevent binding to IgE on mast cells and basophils; Induction of immunological tolerance through peptide or allergen-specific immunotherapy; Reduction of allergen production in the host (feline) via vaccination or dietary antibodies.