Biomarker: F013-IgE Peanut

Overview

F013-IgE Peanut measures immunoglobulin E (IgE) antibodies in blood that bind to peanut allergens. IgE is involved in immediate-type allergic reactions, including reactions to foods. Elevated peanut-specific IgE indicates sensitization and may increase the likelihood of clinical reactivity, while a low or undetectable result makes sensitization less likely. The result does not independently confirm peanut allergy or predict reaction severity and should be interpreted with the clinical history, other allergy testing, and, when appropriate, a medically supervised oral food challenge.

Clinical Use Cases

Evaluation of suspected IgE-mediated peanut allergy in patients with a compatible history of immediate symptoms.
Identification of sensitization to peanut as part of a food-allergy evaluation.
Support for clinical decision-making when considered with medical history and skin-prick testing.
Assessment of patients with suspected peanut allergy who cannot undergo skin-prick testing or whose medications may interfere with skin testing.
Follow-up assessment of peanut-specific IgE over time when clinically indicated.
Use alongside component-resolved diagnostics, particularly IgE to Ara h 2, when whole-peanut IgE results and clinical history are inconclusive.

Specimen Types

Venous blood.
Serum is the usual specimen for laboratory measurement.
Plasma may be used in some research or laboratory assay settings.

Measurement Methods

In vitro allergen-specific IgE immunoassays using whole-peanut allergen extract.
Fluorescence enzyme immunoassays, including solid-phase systems such as ImmunoCAP.
Chemiluminescent or other automated immunoassays, such as IMMULITE systems.
Enzyme-linked immunosorbent assays, primarily in research settings.
Component-resolved immunoassays for peanut proteins such as Ara h 1, Ara h 2, Ara h 3, Ara h 6, Ara h 8, and Ara h 9.
Multiplex allergen microarray assays for simultaneous measurement of IgE to multiple allergen components.

Test Preparation and Influencing Factors

Fasting is generally not required for a peanut-specific IgE blood test.
Patients should report all prescription medicines, over-the-counter medicines, and supplements to the healthcare provider.
Antihistamines generally do not affect blood IgE measurements, although they may interfere with skin-prick testing. Medicines should not be stopped unless instructed by a healthcare professional.
Total IgE concentration, age, atopic conditions, and the patient’s clinical history can influence interpretation.
Cross-reactive sensitization, including sensitization to related plant allergens or cross-reactive carbohydrate determinants, may contribute to positive results without clinically relevant peanut allergy.
Results may vary between assay platforms, so values from different methods should not be compared without considering the assay and its reference range.
A positive result indicates sensitization but does not by itself establish clinical allergy.
Peanut-specific IgE concentration does not reliably predict the severity of a future reaction.
Timing after an allergic reaction may affect interpretation of some allergy evaluations. Persistent or recurrent symptoms should be assessed by an allergy specialist.