High-affinity immunoglobulin epsilon receptor subunit alpha (FcεRIα) (FcεRIα)

The high-affinity immunoglobulin epsilon receptor subunit alpha (FcεRIα) is the primary IgE-binding component of the FcεRI complex found on the surface of mast cells and basophils. In individuals with peanut allergy, this receptor is loaded with peanut-specific IgE antibodies; upon exposure to peanut allergens such as Ara h 1 or Ara h 2, these allergens cross-link the IgE-FcεRI complexes, initiating a signaling cascade that leads to the rapid release of histamine, leukotrienes, and cytokines (UniProt P12319; Galli & Tsai, 2012). This degranulation process is the proximal cause of allergic symptoms, ranging from localized hives to life-threatening systemic anaphylaxis. Therapeutic strategies, most notably the anti-IgE antibody Omalizumab (Xolair), target this system by neutralizing free IgE in the blood, which prevents the formation of new IgE-FcεRI complexes and eventually reduces the density of the receptors on the effector cells (Wood et al., 2024). This mechanism effectively raises the threshold for allergic activation, providing a critical layer of protection against accidental peanut exposure in allergic patients (FDA, 2024).

Other names

Fc epsilon RIHigh affinity IgE receptorIgE receptor type IFCER1APeanut-specific IgE-FcεRI complexPeanut-specific IgE antibodies on mast cells and basophils

Anti-IgE monoclonal antibodies (e.g., Omalizumab) bind to the Cε3 domain of free IgE, preventing its interaction with the high-affinity IgE receptor (FcεRI) on mast cells and basophils. This sequestration of circulating IgE leads to a subsequent downregulation of FcεRI expression on the cell surface, thereby increasing the threshold of allergen required to trigger degranulation and preventing the release of inflammatory mediators (Wood et al., 2024; FDA, 2024).