Biomarker: F352-IgE Ara h 8
Overview
Ara h 8 is a peanut allergen from Arachis hypogaea and belongs to the pathogenesis-related protein 10 (PR-10) family. It is homologous to Bet v 1, the major birch-pollen allergen, and is associated with pollen-food cross-sensitization and peanut-related oral allergy symptoms. Exposure generally occurs through eating peanut, particularly in people sensitized to birch or related tree pollens. Measuring Ara h 8-specific IgE in serum may help characterize peanut sensitization and distinguish possible cross-reactive sensitization from sensitization to peanut storage proteins, but the result alone does not establish clinical peanut allergy.
Clinical Use Cases
Evaluation of suspected IgE-mediated peanut allergy: Ara h 8-specific IgE may be included when the clinical history suggests peanut-related symptoms, particularly in patients with birch-pollen allergy.
Serum-specific IgE assessment: Measurement of F352-IgE evaluates IgE antibodies directed against the Ara h 8 component in a blood-derived sample.
Investigation of oral symptoms: Testing may help evaluate itching or swelling of the lips, mouth, or throat after peanut consumption when pollen-food allergy syndrome is suspected.
Component-resolved diagnostics: Ara h 8 results can be interpreted alongside other peanut components, especially Ara h 1, Ara h 2, and Ara h 3, to characterize the sensitization profile.
Assessment of birch-pollen-associated sensitization: Ara h 8 testing may be useful when peanut-specific IgE is present in a person with birch-pollen sensitization and the clinical history suggests cross-reactivity rather than primary peanut allergy.
Clinical confirmation: Medical history, examination, and, when appropriate, supervised oral food challenge are needed to determine whether sensitization corresponds to symptomatic allergy. Specific IgE testing alone is not diagnostic.
Measurement Methods
Allergen-specific IgE testing: Immunoassays measure IgE antibodies in serum that bind to Ara h 8. Results are generally reported in standardized concentration or class categories, depending on the assay.
Component-resolved diagnostics: Tests measure IgE directed against the individual peanut protein Ara h 8 rather than only against a whole-peanut extract. This can help identify a PR-10-related sensitization pattern.
Related component testing: Ara h 8 may be measured with other peanut components, including Ara h 1, Ara h 2, and Ara h 3, to support clinical interpretation and assessment of potentially different sensitization patterns.
Clinical challenge testing: A medically supervised oral food challenge may be used when the history and laboratory findings do not clearly establish whether peanut ingestion causes clinical reactions. This is not a blood-based measurement method, but it is an important reference approach for diagnosing food allergy.
Test Preparation and Influencing Factors
Preparation: Serum allergen-specific IgE testing generally does not require fasting or other special preparation.
Medications: Patients should report all medicines. Some medicines may affect certain allergy tests, although antihistamines generally do not need to be stopped for blood testing unless the clinician or laboratory specifically advises it. Medicines should not be discontinued without medical guidance.
Sensitization versus clinical allergy: A detectable Ara h 8-specific IgE result demonstrates sensitization, not necessarily symptomatic peanut allergy. Interpretation requires a compatible exposure history and symptoms.
Birch-pollen sensitization: IgE to Ara h 8 may reflect cross-reactivity with Bet v 1, especially in regions or individuals with substantial birch-pollen exposure. This can reduce the specificity of Ara h 8 for primary peanut allergy.
Other peanut components: Results are interpreted with other peanut components. Sensitization to Ara h 2 or other storage proteins may provide different clinical information from isolated Ara h 8 sensitization.
Total IgE concentration: Total IgE and the proportion represented by allergen-specific IgE can affect interpretation. High total IgE may be associated with multiple positive specific-IgE results that are not all clinically relevant.
Age and clinical history: Age, dietary exposure, previous reactions, symptom pattern, and the amount of peanut tolerated are important when interpreting the result.
Assay characteristics: Cutoffs, calibration, component sources, and reporting units can differ between laboratory platforms. Results should be interpreted according to the assay used and in consultation with an allergy specialist.
Timing of testing: A blood test should be interpreted in relation to the patient’s exposure history and any recent reaction. A single result does not determine whether allergy has resolved or whether future exposure will cause symptoms.
Cross-Reactivity
Birch pollen and Bet v 1: Ara h 8 is homologous to Bet v 1, the major birch-pollen allergen. IgE binding to Ara h 8 can therefore result from birch-pollen-driven cross-sensitization.
PR-10 protein family: Ara h 8 belongs to the PR-10 family, which includes homologous allergens in several pollens and plant foods. Structural similarity can produce immunologic cross-reactivity between these sources.
Other related plant allergens: Clinically relevant homologues include Gly m 4 from soybean and Pru av 1 from cherry; related PR-10 allergens also occur in other Fagales tree pollens and plant foods.
Pollen-food allergy syndrome: Ara h 8 sensitization is commonly associated with oral symptoms after eating peanut or other plant foods in birch-pollen-sensitized individuals. Symptoms are often localized to the mouth, but systemic reactions have also been documented in some clinically confirmed peanut-allergic patients.
Clinical interpretation: Isolated Ara h 8 sensitization frequently occurs in children who tolerate peanut or have only mild oral symptoms, but it does not guarantee tolerance. In a clinical challenge study, 129 of 144 children with isolated Ara h 8 sensitization either consumed peanut without reaction or passed challenge, while a small number developed oral or systemic symptoms.
Cross-reactivity versus cross-allergy: Immunologic cross-reactivity shown by serum IgE testing does not prove that exposure to each related food or pollen will cause symptoms. Clinical history and, when necessary, supervised challenge are required to establish clinically meaningful allergy.
Synonyms
Common name: Ara h 8.
Allergen designation: F352.
Scientific source:Arachis hypogaea allergen Ara h 8.
Protein classification: Peanut PR-10 allergen.
Isoallergen designations: Ara h 8.01 and Ara h 8.02, including Ara h 8.0101 and Ara h 8.0201.
This information is provided for general educational purposes and is not medical advice. Biomarker information may describe testing methods, measurements, or interpretations that vary by laboratory or specific test. For details about a particular lab test, including biomarkers measured, specimen type, collection requirements, preparation, and turnaround time, please refer to the individual test description. Talk with a licensed health care provider about your results.
