Allergen-specific IgE Detection on Microarrays Using Rolling Circle Amplification: Correlation with in Vitro Assays for Serum IgE

Allergen-specific IgE antibody in patient serum is used to predict an allergic response in individuals with concordant clinical history. For more than 30 years, in vitro assays for allergen-specific IgE have been used along with or in place of skin-prick allergen testing (SPT) (1). In vitro test methods include various immunoassay formats with solid-phase supports such as paper disks, microtiter plates, nitrocellulose, and microparticles. The field has advanced with immunoassay refinements, including solid phases with higher allergen-binding capacities, monoclonal antibodies for detection, enzyme amplification systems, and fluid-phase allergen/IgE complex formation; these have improved the sensitivity of the in vitro assays and provided better correlation to skin-prick allergen tests (2)(3)(4). SPT and in vitro allergen-specific IgE assays have advantages and disadvantages. SPT results are available immediately, allowing the allergist to provide treatment while the patient is still in the office. Multiple allergen extracts are tested simultaneously on the same patient. Skin-prick tests have the highest positive predictive value because they are biological, but they also have a high false-positive rate. To be administered in vivo, the allergen extracts must be sterile and of low toxicity to prevent anaphylaxis. SPT is expensive because it requires a skilled practitioner. In vitro serum allergen-specific IgE immunoassays are semiquantitative and allow testing of an allergic response over time (4). They are minimally invasive, with no risk of an adverse reaction in the patient, and are the best option in patients with severe skin conditions such as eczema, urticaria, or dermatographism. In food allergy testing, in vitro tests can reduce by one-half the need for oral allergen challenges (4). In vitro tests can also be used with patients receiving medications, such as antihistamines, that may interfere with SPT responsiveness. However, results of in vitro IgE assays can vary between test formats …