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

Major feline allergen 1 (Fel d 1) is a secretoglobin protein and the primary driver of cat-induced allergic reactions in humans, affecting up to 20% of the global population (PMID: 30102319). It is synthesized primarily in the salivary, sebaceous, and perianal glands of domestic cats (Felis catus) and is spread onto the fur during grooming, eventually becoming airborne on dander (PMID: 31289163). Structurally, Fel d 1 is a 35 kDa tetrameric glycoprotein consisting of two non-covalently linked heterodimers, each composed of two disulfide-linked chains (Chain 1 and Chain 2) (UniProt P30438). In sensitized individuals, Fel d 1 cross-links IgE antibodies on the surface of mast cells and basophils, triggering the release of histamine and other inflammatory mediators that cause allergic rhinitis and asthma (PMID: 32654147). Therapeutic strategies targeting Fel d 1 include human monoclonal antibodies designed to neutralize the allergen, feline vaccines that induce anti-Fel d 1 antibodies in the cat to reduce environmental shedding, and specialized cat food containing IgY antibodies to neutralize the protein in the cat's saliva.

Other names

Fel d IFeline domesticus allergen 1Secretoglobin family 1D member 1Secretoglobin family 1D member 2Feline allergen 1

Neutralization of the Fel d 1 protein to prevent its binding to IgE antibodies on mast cells and basophils, thereby inhibiting the allergic cascade. In feline-directed therapies, the mechanism involves reducing the amount of active Fel d 1 shed into the environment through vaccination or dietary neutralization.