High-affinity immunoglobulin E receptor (Fc epsilon RI) complexed with allergen-specific IgE (FcεRI-IgE-allergen complex)

The *Allergen-specific IgE receptor complex* is best described as the formation of a tripartite structure between an allergen, allergen-specific IgE, and the high-affinity IgE receptor (FcεRI) on the surface of effector cells (such as mast cells and basophils)[1][2]. Upon exposure to an allergen, cross-linking of FcεRI-bound IgE molecules by the allergen leads to cell activation and degranulation, causing the rapid release of inflammatory mediators and driving allergic symptoms that range from mild (rhinorrhea, itchiness) to severe (anaphylaxis)[1][5][7]. FcεRI itself is a multimeric receptor with cell type-dependent composition: tetrameric on mast cells/basophils and trimeric on antigen-presenting cells (notably dendritic cells, monocytes, Langerhans cells)[3]. The high specificity and affinity of IgE for FcεRI, and the requirement for minimal allergen to trigger degranulation, make this complex a critical target in allergic disease therapeutics[1][5]. Drugs such as omalizumab work by neutralizing circulating IgE, thereby reducing FcεRI occupancy and dampening allergic responses[1][5].

Other names

IgE-FcεRI-allergen complexIgE receptor complexFc epsilon RI-IgE complexHigh-affinity IgE receptor (FcεRI) complexFcεRI complexFcεRI-IgE-allergen tripartite complex

Neutralization of IgE (prevents IgE from binding FcεRI; e.g., omalizumab) Prevention of FcεRI cross-linking (blocks cell activation and mediator release) Downregulation of FcεRI receptor expression (caused by reduced IgE levels) Inhibition of IgE synthesis (when targeting CD23)