Biomarker: G002-IgE Bermuda Grass

Overview

G002-IgE Bermuda Grass measures allergen-specific immunoglobulin E (IgE) antibodies directed against Bermuda grass pollen, Cynodon dactylon. Bermuda grass pollen is a subtropical aeroallergen associated with IgE-mediated respiratory conditions, including seasonal allergic rhinitis, conjunctivitis, and asthma. A high result indicates sensitization to Bermuda grass, while a low or undetectable result indicates that clinically significant Bermuda grass-specific IgE was not detected. The result supports evaluation of suspected pollen allergy but must be interpreted with symptoms, exposure history, and other allergy-test findings because the concentration does not predict reaction severity.

Clinical Use Cases

Supports evaluation of seasonal allergic rhinitis, conjunctivitis, asthma, or other symptoms that occur with grass-pollen exposure.
Identifies sensitization to Bermuda grass when a patient’s geographic location or exposure history suggests subtropical grass-pollen allergy.
Helps distinguish Bermuda grass sensitization from sensitization to temperate grasses, which may show limited cross-reactivity in some subtropical populations.
Complements skin-prick testing when skin testing is unsuitable because of skin disease, medication use, age, or concern about systemic reactions.
Supports selection of relevant allergens for avoidance counseling and consideration of allergen-specific immunotherapy by an allergy specialist.
May be used in research to study Bermuda grass pollen allergens, IgE recognition, cross-reactivity, and allergic respiratory disease.

Specimen Types

Serum from venous blood.
Plasma or capillary-blood-derived samples may be accepted by some validated immunoassay systems, according to the specific assay instructions.
Skin-prick-test extracts are not specimens for measuring this biomarker but may be used as an alternative method for detecting allergen-specific IgE.

Measurement Methods

Fluorescence-based quantitative allergen-specific IgE immunoassays.
Enzyme-linked immunosorbent assays (ELISA).
Radioallergosorbent testing (RAST), an older method that is now largely replaced by newer immunoassays.
Immunoblot or line-blot assays for research or component-resolved assessment.
Molecular component testing for Bermuda grass allergens such as Cyn d 1, when available. Cyn d 1 is a major Bermuda grass pollen allergen recognized by IgE from allergic human sera.

Test Preparation and Influencing Factors

Fasting is generally not required for an allergy-specific IgE blood test.
No special preparation is usually required, although the ordering clinician or testing facility may provide assay-specific instructions.
Patients should report all medications and supplements. Medication changes should be made only when specifically instructed by a healthcare professional.
Unlike skin-prick testing, blood specific-IgE measurement is generally not materially affected by antihistamines; antihistamines can suppress skin-test reactions.
Collection timing is usually not restricted to the pollen season because circulating allergen-specific IgE can be measured outside the exposure period.
Results should be interpreted alongside symptom timing, local pollen exposure, clinical history, and physical examination.
A positive result indicates sensitization and does not by itself prove that Bermuda grass causes the patient’s symptoms.
The measured IgE concentration does not predict the severity of a future allergic reaction.
Total IgE, smoking, parasitic infection, and other medical factors may complicate interpretation of allergy testing, particularly when results are discordant with the clinical history.