Biomarker: F342-IgE Olive, Black

Overview

Black olive is the ripe fruit of the olive tree, Olea europaea, and belongs to the plant-food allergen category. IgE-mediated reactions to olive fruit are uncommon but have been reported, including oral itching, urticaria, angioedema, and other immediate symptoms after ingestion. Exposure generally occurs through eating whole black olives or foods containing olive products. Serum-specific IgE testing may help evaluate suspected sensitization, but a positive result indicates sensitization and does not by itself establish a clinically confirmed allergy.

Clinical Use Cases

Evaluation of suspected IgE-mediated food allergy: Serum-specific IgE to olive may support assessment when symptoms occur soon after eating black olives or related olive products.
Investigation of exposure-associated symptoms: Testing may be considered for immediate oral, cutaneous, gastrointestinal, or respiratory symptoms temporally associated with olive ingestion.
Serum allergen-specific IgE assessment: Measurement of IgE antibodies to olive extract can help identify sensitization in a blood sample when testing is clinically indicated.
Clinical history correlation: Results should be interpreted with the type of olive consumed, amount eaten, timing of symptoms, reproducibility, and alternative explanations.
Assessment alongside other allergy testing: Serum-specific IgE may be used with skin-prick or prick-to-prick testing when appropriate. These tests demonstrate sensitization and do not independently confirm clinical allergy.
Confirmation in uncertain cases: A medically supervised oral food challenge may be considered when the history and IgE-based testing do not establish whether olive ingestion causes clinical reactions.

Specimen Types

Serum: Commonly used for measurement of olive-specific IgE.
Plasma: May be accepted by some validated laboratory immunoassays, depending on the laboratory method.

Measurement Methods

Allergen-specific IgE testing: In-vitro immunoassays measure circulating IgE antibodies that bind proteins in an olive extract, usually from a blood-derived specimen.
Immunoassay platforms: Clinically used serum-specific IgE methods may include fluorescent enzyme, chemiluminescent, enzyme-linked, or related immunoassay formats. Results are reported using the platform’s units and interpretive ranges.
Component-resolved diagnostics: Testing for individual olive proteins may help investigate sensitization patterns when clinically available, although component testing is better established for some foods than for olive fruit.
Skin testing: Skin-prick or prick-to-prick testing with olive extract or fresh olive may provide complementary evidence, particularly when extract-based blood testing does not reflect the suspected food exposure.
Oral food challenge: A medically supervised challenge assesses clinical reactivity rather than sensitization alone and is reserved for cases in which the diagnosis remains uncertain.

Test Preparation and Influencing Factors

Fasting: Fasting is generally not required for serum-specific IgE blood testing unless other tests collected during the same visit require it.
Medications: Antihistamines generally do not interfere with serum-specific IgE measurement, although they can suppress skin-test responses. Medication decisions should follow the clinician’s instructions.
Timing of collection: Testing can usually be performed independently of the most recent olive exposure. A recent reaction may make the clinical history more informative, but the appropriate timing depends on the suspected reaction and clinician assessment.
Total IgE concentration: Very high total IgE, particularly in severe atopic dermatitis, can increase the likelihood of clinically insignificant positive specific-IgE results and requires cautious interpretation.
Age and clinical context: Reference ranges and the likelihood that sensitization is clinically relevant can vary with age, population, diet, and exposure history.
Extract composition: Olive-specific IgE assays use allergen extracts whose protein composition may vary. A negative result does not exclude allergy if the relevant allergen is absent or present in low concentration.
Cross-reactive sensitization: IgE binding to proteins shared with olive pollen or other plant foods can produce a positive result without demonstrating symptomatic allergy to black olive.
Sensitization versus allergy: A detectable olive-specific IgE result demonstrates immunologic sensitization. Clinical allergy requires compatible symptoms after exposure and, when necessary, confirmation through medically supervised challenge.
Result magnitude: Higher specific-IgE concentrations may increase the probability of clinical reactivity in some settings, but the value does not reliably predict reaction severity or guarantee that a reaction will occur.

Cross-Reactivity

Olive pollen: Human reports describe patients with olive fruit reactions who also had sensitization to olive pollen, suggesting that shared allergenic structures may contribute in some individuals. This relationship is not universal, and olive-pollen sensitization alone does not establish olive-fruit allergy.
Profilins: Olive pollen profilin, including Ole e 2, can cross-react with profilins in several plant foods. This pattern is associated particularly with pollen-food allergy syndrome and may produce oral symptoms, although clinical responses vary.
Lipid-transfer proteins: Olive pollen lipid-transfer protein Ole e 7 may cross-react with lipid-transfer proteins in fruits such as peach, pear, melon, and kiwi. Sensitization to this protein family may be associated with more systemic reactions, but the clinical significance must be assessed for the individual patient.
Related plant foods: In olive-pollen-associated food allergy, reported cross-reactive foods include peach, pear, melon, kiwi, and some nuts. These findings concern olive-pollen sensitization patterns and should not be interpreted as proof of cross-allergy to black olives.
Oleaceae pollens: Olive pollen shows clinically documented cross-reactivity with pollens from related Oleaceae plants, including ash, privet, lilac, and Russian olive. This evidence primarily concerns respiratory pollen allergy rather than black-olive ingestion.
Clinical relevance: Immunologic cross-reactivity detected by serum or inhibition testing does not necessarily produce symptoms after exposure to each related allergen. Clinical history and, when indicated, supervised challenge are needed to establish clinically meaningful cross-allergy.

Synonyms

Common name: Black olive
Food name: Ripe olive
Scientific name:Olea europaea
Allergen designation: F342 Olive
Related allergen designation: Olive fruit allergen, distinct from olive pollen allergen Ole e 1