Fel d 1-specific Immunoglobulin E bound to High-affinity IgE receptor (FcεRI) (Fel d 1-IgE-FcεRI complex)

The Fel d 1-specific Immunoglobulin E (IgE) bound to the High-affinity IgE receptor (FcεRI) is the central molecular complex mediating Type I hypersensitivity reactions in cat-allergic individuals. Fel d 1, a secretoglobin protein primarily secreted by feline sebaceous and salivary glands, is the major allergen responsible for over 90% of cat allergies [1]. In sensitized patients, Fel d 1-specific IgE antibodies are produced and subsequently dock with high affinity onto FcεRI receptors located on the surface of mast cells and basophils [2]. Upon re-exposure to cat dander, Fel d 1 proteins act as multivalent antigens that cross-link these pre-bound IgE molecules, triggering an intracellular signaling cascade that leads to the rapid degranulation of the effector cells and the release of inflammatory mediators such as histamine, leukotrienes, and cytokines [3]. This physiological response results in the clinical symptoms of cat allergy, including allergic rhinitis, conjunctivitis, and potentially life-threatening asthma exacerbations. Therapeutic strategies targeting this complex include monoclonal antibodies like REGN1908 and REGN1909, which neutralize Fel d 1 to prevent it from reaching the IgE-FcεRI complex, and anti-IgE therapies like Omalizumab, which deplete the pool of circulating IgE to prevent the initial formation of the complex on the cell surface [4].

Other names

Cat allergen-specific IgE-FcεRI complexFel d 1-IgE-FcεRISensitized mast cell IgE complexIgE-FcεRI complex

Neutralization of the Fel d 1 allergen to prevent cross-linking of receptor-bound IgE, inhibition of free IgE binding to the FcεRI receptor, and reduction of surface IgE density on effector cells.