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

Major cat allergen Fel d 1 (Fel d 1) is a secretoglobin protein produced primarily in the sebaceous and salivary glands of cats (Bonnet et al., 2018). It is the primary driver of cat-related allergic diseases, including allergic rhinitis and asthma, affecting approximately 10% of the population in Western countries (Gronlund et al., 2003). The protein exists as a 35 kDa tetramer composed of two heterodimers, which present multiple epitopes for IgE binding (Kaye and Chapman, 1991). Therapeutic strategies focus on neutralizing these epitopes or inducing a shift in the immune response from IgE-mediated hypersensitivity to IgG-mediated tolerance (Oren et al., 2022). Specifically, allergen-specific immunotherapy (AIT) and monoclonal antibodies like REGN1908/1909 aim to produce or provide IgG antibodies that compete with endogenous IgE for the same epitopes on Fel d 1 (Sabato et al., 2017). By blocking IgE binding, these interventions prevent the cross-linking of FcεRI receptors on mast cells and basophils, effectively inhibiting the release of inflammatory mediators (Oren et al., 2022). This competition between IgG and IgE is a hallmark of successful desensitization in allergic patients. Fel d 1 is considered the gold standard target for cat allergy diagnostics and therapeutic development due to its high prevalence of IgE reactivity.

Other names

Felis domesticus allergen 1Cat dander allergenSecretoglobinCat allergen 1

Induction of allergen-specific IgG antibodies (particularly IgG4) that compete with IgE for binding to Fel d 1 epitopes, thereby preventing IgE-mediated mast cell and basophil degranulation.