Biomarker: F084-IgE Kiwi Fruit

Overview

F084-IgE Kiwi Fruit measures serum immunoglobulin E (IgE) antibodies that recognize proteins in kiwifruit, including allergens such as actinidin (Act d 1), thaumatin-like protein (Act d 2), and PR-10 protein (Act d 8). Detectable kiwi-specific IgE indicates sensitization, but it does not by itself establish a clinical food allergy or predict reaction severity. Kiwifruit allergy can cause oral allergy symptoms, urticaria, gastrointestinal or respiratory symptoms, and anaphylaxis. The test is clinically useful when interpreted with the patient’s history and, when necessary, skin testing or a medically supervised oral food challenge.

Clinical Use Cases

Supports evaluation of suspected IgE-mediated allergy to kiwifruit.
Identifies sensitization to kiwifruit proteins after compatible symptoms following ingestion or contact.
Helps evaluate possible cross-reactivity involving birch or grass pollen, latex, banana, avocado, or other plant foods.
May be used with component-resolved diagnosis to assess IgE recognition of individual kiwifruit allergens, such as Act d 1, Act d 2, Act d 8, and Act d 10.
Supports, but does not replace, clinical history, skin-prick testing, and medically supervised oral food challenge.

Specimen Types

Venous blood, processed to obtain serum.
In selected research or specialized diagnostic settings, plasma may be used if validated by the laboratory method.

Measurement Methods

In-vitro allergen-specific serum IgE immunoassay.
Enzyme-linked immunosorbent assay (ELISA).
Fluorescence enzyme immunoassay, including ImmunoCAP-type platforms.
Component-resolved diagnosis using purified or recombinant kiwifruit allergens.
Multiplex allergen microarray assays in specialized research or clinical settings.

Test Preparation and Influencing Factors

Fasting is generally not required for an allergy blood test.
Tell the healthcare provider about all medications and supplements. Some medicines, particularly antihistamines, may affect certain allergy tests, although blood specific-IgE testing is generally less affected than skin testing.
Do not discontinue prescribed medicines unless directed by a healthcare professional.
Results should be interpreted with the timing, reproducibility, amount, and form of kiwifruit exposure, including whether it was raw or cooked.
A positive result indicates sensitization and may occur without clinically significant allergy.
A negative or low result does not completely exclude allergy, particularly when relevant kiwifruit allergens are unstable or poorly represented in the extract.
Assay platforms, allergen extracts, reporting units, and reference ranges differ between laboratories; results should be interpreted using the reporting laboratory’s criteria.
Kiwifruit-specific IgE concentrations do not reliably predict the severity of a future reaction.
Fresh-fruit skin-prick or prick-to-prick testing may be more sensitive than testing with some commercial kiwifruit extracts because allergen stability can affect test performance.