Felis domesticus allergen 1 (Fel d 1) (Fel d 1)

Felis domesticus allergen 1 (Fel d 1) is the primary secretoglobin protein responsible for over 90% of cat-related allergies in humans, produced predominantly in the sebaceous, salivary, and perianal glands of cats (UniProt P30438, P30440). Structurally, it is a 35 kDa tetrameric glycoprotein formed by two non-covalently linked heterodimers, each consisting of a Chain 1 and a Chain 2 joined by disulfide bonds (Grönlund et al., 2010, Journal of Biological Chemistry). In sensitized individuals, Fel d 1 cross-links allergen-specific IgE on the surface of mast cells and basophils, triggering the release of inflammatory mediators that drive allergic rhinitis and asthma symptoms. Modern therapeutic approaches target the immunological recognition of Fel d 1 by using monoclonal antibodies, such as the combination of Gancotamab and Exebatarnig, to sequester the allergen before it can interact with IgE (Orengo et al., 2018, Nature Communications). Additionally, peptide-based immunotherapies like Cat-PAD utilize specific T-cell epitopes to induce peripheral T-cell tolerance and promote the production of protective IgG4 blocking antibodies, which compete for the same B-cell epitopes as IgE to inhibit the allergic cascade (Worm et al., 2011, Journal of Allergy and Clinical Immunology).

Other names

Major cat allergenFelis domesticus 1Secretoglobin family 1D member 1SCGB1D1Cat allergen 1

Therapeutic strategies involve neutralizing the allergen using monoclonal antibodies to prevent IgE binding, or utilizing peptide-based immunotherapy to induce T-cell tolerance (anergy) and stimulate the production of Fel d 1-specific IgG4 blocking antibodies that compete with IgE for allergen epitopes.