Biomarker: F218-IgE Paprika/Sweet Pepper

Overview

F218-IgE measures serum allergen-specific immunoglobulin E (sIgE) directed against paprika or sweet pepper, generally associated with Capsicum annuum. IgE sensitization can support evaluation of immediate allergic reactions to fresh sweet pepper, paprika, or related Capsicum products, including occupational respiratory reactions. A high result indicates sensitization but does not by itself establish clinical allergy, predict reaction severity, or confirm that paprika or sweet pepper caused symptoms. The test is clinically useful when interpreted with the exposure history, symptoms, and, when necessary, skin testing or a medically supervised oral food challenge.

Clinical Use Cases

Supports evaluation of suspected IgE-mediated allergy to paprika, sweet pepper, bell pepper, or related Capsicum products.
Helps investigate immediate symptoms such as urticaria, angioedema, gastrointestinal symptoms, respiratory symptoms, or anaphylaxis occurring after exposure.
May support assessment of occupational rhinitis or rhinoconjunctivitis associated with repeated handling or inhalation of paprika or pepper materials.
Helps identify sensitization when skin-prick testing is contraindicated, unavailable, or difficult to interpret.
May be considered when evaluating possible cross-sensitization among paprika, sweet pepper, chili pepper, and cayenne pepper, although clinical relevance requires correlation with symptoms.
Contributes to diagnostic assessment but should not be used as an indiscriminate food-allergy screening test.

Specimen Types

Venous blood, with serum used for measurement of allergen-specific IgE.
Plasma may be accepted by some assay systems, according to the performing laboratory’s validation requirements.

Measurement Methods

In-vitro allergen-specific IgE immunoassay using paprika or sweet-pepper extract.
Fluorescence enzyme immunoassay, including automated solid-phase systems.
Enzyme-linked immunosorbent assay, chemiluminescent immunoassay, or other validated immunoassay formats.
Immunoblotting or related research methods for characterizing IgE-binding paprika or Capsicum proteins, rather than routine clinical quantification.
Results are commonly reported as an allergen-specific IgE concentration in kUA/L and/or as an assay-class category. Reference intervals and reporting conventions vary by method.

Test Preparation and Influencing Factors

Fasting is generally not required for an allergy blood test.
Antihistamines usually do not interfere with serum-specific IgE measurement, but medications and supplements should be reported because some allergy tests, particularly skin tests, can be affected.
Do not stop prescribed medicines unless instructed by the treating clinician.
Testing should be selected according to a detailed history of food intake, occupational exposure, timing, symptoms, and reproducibility.
Recent exposure, age, time since the last reaction, total IgE concentration, other atopic conditions, and the assay method can influence interpretation.
A positive result indicates sensitization and may reflect cross-reactivity, including reactions involving related Capsicum species or pollen-associated proteins.
A negative result does not absolutely exclude clinical allergy, particularly when the extract does not represent the relevant food preparation or allergen.
Serum-specific IgE concentration does not reliably predict reaction severity.
Broad food-allergen panels can produce clinically irrelevant positive results and are not recommended without a compatible clinical history.
If history and testing remain inconclusive, an allergist may consider a medically supervised oral food challenge, which is the diagnostic reference standard for food allergy.