Biomarker: F207-IgE Clam

Overview

F207-IgE Clam measures serum allergen-specific immunoglobulin E (sIgE) antibodies directed against clam proteins. IgE is an antibody involved in immediate-type allergic reactions; binding of allergen-specific IgE to immune cells can trigger release of mediators that cause allergy symptoms. A detectable or elevated result indicates sensitization to clam, but does not by itself confirm clinical clam allergy or predict reaction severity. The test is clinically useful as part of an allergy evaluation guided by the patient’s history, particularly when skin testing is unsuitable or additional evidence of sensitization is needed.

Clinical Use Cases

Evaluate suspected IgE-mediated clam or mollusk allergy.
Identify sensitization after symptoms such as hives, angioedema, gastrointestinal symptoms, wheezing, or anaphylaxis occurring after clam exposure.
Support evaluation of suspected occupational allergy or asthma associated with clam handling or processing.
Assess possible sensitization to multiple shellfish species, while accounting for cross-reactivity among shellfish and with dust mites or cockroaches.
Complement clinical history and skin-prick testing when determining whether a medically supervised oral food challenge is appropriate.
Support, but not replace, an oral food challenge when the diagnosis remains uncertain. Oral food challenge is the reference standard for confirming food allergy.

Specimen Types

Venous whole blood collected for laboratory separation of serum.
Serum is the usual specimen for quantitative clam-specific IgE measurement.
Plasma may be accepted by some assay systems, depending on the laboratory method.

Measurement Methods

In vitro allergen-specific IgE immunoassay using clam extract coupled to a solid phase.
Fluorescence enzyme immunoassay or comparable automated solid-phase immunoassay.
Enzyme-linked immunosorbent assay methods in research settings.
Immunoblotting or other research allergen-binding assays for characterization of clam-reactive proteins, rather than routine clinical diagnosis.
Component-resolved testing may assess individual shellfish allergens, such as tropomyosin, when available; validated clam-specific component testing is limited.

Test Preparation and Influencing Factors

Fasting is generally not required for an allergy blood test.
Patients should report all medications and supplements. Antihistamines usually do not prevent blood sIgE measurement, although medication instructions may vary if skin testing is performed at the same time.
Results should be interpreted with the timing, amount, preparation of clam, symptoms, and other exposures recorded in the clinical history.
A positive result indicates sensitization and may occur without symptoms after eating clam. It should not be used alone to diagnose allergy.
The measured sIgE concentration does not reliably predict the severity of a future allergic reaction.
Cross-reactive IgE to tropomyosin and related proteins in shellfish, dust mites, or cockroaches can contribute to positive clam results without clinically relevant clam allergy.
A negative result does not completely exclude allergy, particularly when the clinical history is strongly suggestive or when the relevant clam allergens are not adequately represented in the test extract.
Total IgE, age, assay platform, reporting units, and laboratory-specific reference ranges can influence interpretation.
Oral food challenges should be performed only under appropriate medical supervision because they can provoke an allergic reaction.