IgE

Overview

IgE measures the concentration of immunoglobulin E, a class of antibody mainly produced by plasma cells in response to allergens, parasites, and some infections. IgE binds with high affinity to Fcε receptors on mast cells and basophils, triggering the release of histamine and other mediators during type‑I immediate hypersensitivity reactions. Elevated total or allergen‑specific IgE levels are associated with allergic conditions such as asthma, allergic rhinitis, atopic dermatitis, and food allergies, whereas very low levels may occur in some immune‑deficiency states. Because of its role in allergic inflammation, IgE testing is clinically useful for evaluating allergic disease and for guiding allergen‑specific testing and immunotherapy.

Clinical Use Cases

  • Evaluating suspected allergic disease (e.g., asthma, allergic rhinitis, atopic dermatitis).
  • Supporting diagnosis of anaphylaxis risk and food‑ or environmental‑allergen hypersensitivity.
  • Assessing parasitic infestations (e.g., helminths) that provoke marked IgE elevation.
  • Helping characterize certain primary immunodeficiency patterns (e.g., very low IgE) in combination with other immunoglobulins.

Specimen Types

  • Serum (most common specimen for total and allergen‑specific IgE).
  • Plasma (less commonly used; serum is standard for IgE immunoassay).

Measurement Methods

  • Immunoassay (chemiluminescent or immuno‑fluorescent assays) for total IgE on automated platforms.
  • Fluorescent enzyme‑immunoassay (e.g., ImmunoCAP, ImmunoCAP ISAC) for allergen‑specific IgE.
  • ELISA methods in some research or reference‑laboratory settings.

Test Preparation and Influencing Factors

  • No fasting required, but consistency in collection time and specimen handling is recommended.
  • Recent exposure to an allergen, acute allergic reaction, or antihistamine/steroid therapy may affect levels.
  • Helminthic infections, atopic multimorbidity, and chronic allergic inflammation can markedly increase IgE.
  • Serum storage and repeated freeze‑thaw cycles can compromise IgE stability on testing.

Synonyms

  • Immunoglobulin E.
  • IgE, total IgE.
  • Allergen‑specific IgE (when measured against defined allergens).

Further Reading