Human immunoglobulin E reactive with Felis domesticus allergen 1 (Fel d 1-specific IgE)

Human immunoglobulin E (IgE) reactive with Fel d 1 represents the primary mediator of cat-induced allergic reactions in sensitized individuals. Fel d 1 is a secretoglobin protein and the dominant allergen produced by cats, primarily in their salivary and sebaceous glands (Bonnet et al., 2018). In the allergic cascade, these specific IgE antibodies are produced by B cells and subsequently bind to high-affinity FcεRI receptors on the surface of mast cells and basophils. Upon exposure to cat dander, the Fel d 1 allergen cross-links these surface-bound IgE molecules, triggering the immediate release of inflammatory mediators such as histamine, prostaglandins, and leukotrienes (Galli & Tsai, 2012). This process results in the clinical manifestations of cat allergy, including rhinoconjunctivitis, urticaria, and potentially severe exacerbations of asthma. Therapeutic strategies targeting these antibodies include the use of omalizumab, a humanized monoclonal antibody that binds to the Fc region of circulating IgE, thereby preventing its interaction with FcεRI and reducing the overall allergic potential (FDA, 2003). Another approach involves the use of allergen-neutralizing monoclonal antibodies, such as the combination of REGN1908 and REGN1909, which are designed to bind to Fel d 1 itself, effectively sequestering the allergen and preventing it from cross-linking the patient's IgE (Orengo et al., 2018). Additionally, allergen-specific immunotherapy (AIT) aims to induce immune tolerance by promoting the production of "blocking" IgG4 antibodies that compete with IgE for allergen binding, ultimately reducing the activation of effector cells (Valenta et al., 2016).

Other names

Fel d 1-specific IgEAnti-Fel d 1 IgECat allergen-specific IgEsIgE to Fel d 1Human IgE reactive with Fel d 1

Anti-IgE therapies (e.g., omalizumab) bind to the Cε3 domain of the IgE molecule, preventing it from binding to the high-affinity FcεRI receptor on effector cells (FDA, 2003). Allergen-neutralizing therapies (e.g., REGN1908/1909) bind to the Fel d 1 allergen, preventing it from cross-linking the specific IgE antibodies on the surface of mast cells and basophils, thereby inhibiting degranulation (Orengo et al., 2018).