Immunoglobulin E (allergen-specific) (IgE)

Immunoglobulin E (IgE) is an antibody found in mammals, synthesized by plasma cells. Its primary physiological role is to mediate immune defense against parasitic infections, but it is most well-known for its involvement in allergic reactions. Allergen-specific IgE circulates at very low concentrations but binds with high affinity to FcεRI (high-affinity IgE receptor) and CD23 (FcεRII, low-affinity receptor) on immune cells—chiefly mast cells, basophils, and some antigen-presenting cells. Upon exposure, cross-linking of cell-bound allergen-specific IgE by allergen triggers cell activation, degranulation, and release of inflammatory mediators such as histamine, leading to symptoms of allergy and, potentially, severe anaphylaxis. Diagnostic tests for allergy rely on detection of specific IgE. Blocking IgE, such as with omalizumab, is used therapeutically in severe allergic and certain autoimmune conditions.

Other names

IgEAllergen-specific IgEIgE antibodyImmune cell-bound IgE

Blocking IgE binding to FcεRI/CD23 (preventing mast cell/basophil activation) Reducing circulating IgE levels Competing with allergen for IgE binding (immunotherapy)