Biomarker: G010-IgE Johnson Grass

Overview

G010-IgE Johnson Grass measures serum-specific immunoglobulin E (IgE) antibodies directed against Johnson grass pollen, Sorghum halepense. Johnson grass is a subtropical grass whose pollen can trigger allergic rhinitis, conjunctivitis, and asthma in sensitized individuals. A detectable result indicates immunologic sensitization, but does not by itself confirm that exposure causes symptoms or predict their severity. Testing is clinically useful when evaluating seasonal respiratory allergy and identifying relevant grass-pollen sensitization, particularly in subtropical regions.

Clinical Use Cases

Evaluation of suspected Johnson grass pollen allergy in patients with seasonal rhinitis, conjunctivitis, or asthma.
Identification of grass-pollen sensitization when the clinical history suggests exposure-related symptoms.
Supporting differential diagnosis in patients with seasonal respiratory symptoms.
Selection of relevant allergens for specialist evaluation and possible allergen immunotherapy.
Research on species-specific and cross-reactive IgE responses among subtropical grasses.

Specimen Types

Venous blood, typically collected as serum.
Plasma may be accepted by some assay systems, according to the laboratory’s validated specimen requirements.

Measurement Methods

Fluorescence enzyme immunoassay or other solid-phase immunoassay for quantitative serum-specific IgE.
Enzyme-linked immunosorbent assay, used in human research studies of Johnson grass pollen IgE.
Immunoblotting or Western blotting, primarily for research characterization of IgE-binding pollen proteins.
Component-resolved IgE immunoassays for individual Johnson grass allergens such as Sor h 1, Sor h 2, Sor h 13, and Sor h 23, where available.

Test Preparation and Influencing Factors

Fasting is generally not required for an allergy blood test.
Tell the healthcare provider about all medications, supplements, and relevant medical conditions.
Do not stop prescribed medicines unless instructed by a healthcare professional.
Antihistamines generally do not interfere with serum-specific IgE measurement, although they can affect skin-prick testing.
Results should be interpreted with the exposure history, symptom pattern, physical findings, and other allergy-testing results.
A positive result indicates sensitization and does not establish clinical allergy, symptom severity, or the likelihood of a reaction on every exposure.
Cross-reactivity with other grass pollens may contribute to a positive result and should be considered during interpretation.
Serum-specific IgE concentration does not reliably predict the timing or severity of seasonal symptoms.