Fel d 1-specific immunoglobulin E (Fel d 1-specific IgE)

Fel d 1-specific immunoglobulin E (IgE) is a specialized antibody produced by the immune system in individuals sensitized to Fel d 1, the primary secretoglobin allergen found in cat saliva and dander (Bonnet et al., 2018). These IgE molecules circulate in the blood and bind to high-affinity FcεRI receptors on the surface of mast cells and basophils. Upon re-exposure to cat allergens, the Fel d 1 protein cross-links the bound IgE, triggering the immediate release of inflammatory mediators like histamine and leukotrienes, which cause symptoms of allergic rhinitis, conjunctivitis, and asthma (Gould & Sutton, 2008). As a therapeutic target, Fel d 1-specific IgE is addressed through two main pharmacological approaches: non-specific sequestration by anti-IgE monoclonal antibodies and specific reduction through allergen-specific immunotherapy (AIT). Omalizumab, a recombinant humanized monoclonal antibody, binds to the Fc region of IgE, preventing its interaction with FcεRI and effectively lowering the levels of free, allergen-specific IgE available to trigger reactions (Normansell et al., 2014). Alternatively, AIT aims to modify the underlying disease by shifting the immune response away from IgE production toward protective IgG4 antibodies and T-cell tolerance (Davila et al., 2018).

Other names

Cat allergen-specific IgEAnti-Fel d 1 IgEFelis domesticus allergen 1-specific IgEFel d 1-sIgE

Neutralization of circulating IgE by binding to the Cε3 domain, which prevents the antibody from interacting with the high-affinity IgE receptor (FcεRI) on mast cells and basophils, thereby inhibiting the allergic cascade (Gould & Sutton, 2008).