Biomarker: F222-IgE Tea

Overview

F222-IgE Tea is a blood test that measures immunoglobulin E (IgE) antibodies directed against tea extract, generally based on fermented black tea or a blend of black teas. Detectable tea-specific IgE indicates sensitization, but it does not by itself establish a clinical tea allergy or predict reaction severity. Higher concentrations may increase the likelihood that sensitization is clinically relevant when they match a compatible history of symptoms after tea exposure, while a negative result does not completely exclude allergy. The test can support evaluation of suspected immediate hypersensitivity to tea, but results should be interpreted with clinical history and, when appropriate, skin testing or supervised oral food challenge.

Clinical Use Cases

Supporting evaluation of suspected IgE-mediated allergy to tea in patients with compatible symptoms after exposure.
Identifying sensitization to tea extract as part of an allergy-focused diagnostic workup.
Helping distinguish suspected tea-related reactions from other possible causes when guided by the clinical history.
Supporting specialist evaluation when skin-prick testing is unsuitable or cannot be performed.
Research assessment of tea-specific IgE sensitization in human subjects.

Specimen Types

Serum obtained from venous blood.
Plasma may be accepted by some assay systems, depending on the laboratory method and validated specimen requirements.

Measurement Methods

Fluorescence enzyme immunoassay, including ImmunoCAP-type quantitative specific-IgE testing.
Other validated immunoassays for allergen-specific IgE, depending on the laboratory platform.
Results are commonly reported in kU/L or kUA/L and may also be assigned an assay-specific class or category.

Test Preparation and Influencing Factors

No fasting or other special preparation is generally required for an allergy blood test.
Patients should provide a complete list of medications and supplements. Antihistamines usually do not prevent blood collection, but medication instructions vary by test and provider.
Patients should not stop prescription or nonprescription medicines unless instructed by a healthcare professional.
Recent or ongoing exposure to tea does not generally require avoidance before blood collection, but the timing and nature of symptoms should be documented.
Results may be affected by differences in allergen extracts, assay platforms, reporting thresholds, and laboratory calibration.
A positive result indicates sensitization and may occur without symptoms on exposure; it should not be used alone to diagnose tea allergy.
A negative result does not absolutely exclude clinical allergy, particularly because F222 testing may not detect sensitization to all relevant tea allergens or tea preparations.
The concentration of tea-specific IgE does not reliably predict the severity of a reaction.