OBJECTIVE: To develop and evaluate a liquid phase immunoassay for accurate determination of allergen-specific IgE (sIgE) as a useful tool in the diagnosis of allergy patients.

DESIGN AND METHODS: A fully automated, quantitative sIgE assay was developed for the ADVIA Centaur technology platform using a unique calibration method based on a recombinant reference allergen. Compared to most other IgE-assays, the assay employs a reverse sandwich architecture using monoclonal mouse anti-human IgE antibody covalently bound to paramagnetic particles in the solid phase and capturing the sample IgE. Bound sIgE reacts with liquid biotin-labeled allergen, which is detected as chemiluminescence using acridiniumester-labeled streptavidin.

RESULTS: The ADVIA Centaur sIgE assay (Centaur assay) has exclusive reactivity to human IgE and performs with excellent linearity in the assay range 0.35-100 kU/L and high precision (imprecision within-run <2.6%, between-run <4.9%, and total imprecision <7.1%). The analytical sensitivity is <0.10 kU/L. Using Pharmacia CAP system FEIA (CAP) as a comparative method, positive/negative concordance was 94% at 0.35 kU/L cut-off, and the Centaur assay has a sensitivity of 90% and a specificity of 98%. Validation of the assay in a general population sample (The Copenhagen allergy study) revealed that sIgE was highly associated with a clinical diagnosis of inhalation allergy.

CONCLUSIONS: The Centaur assay is an allergen-specific assay for measurement of IgE without interference from other types of immunoglobulins or nonspecific IgE. The assay performs with a linear reaction, high assay range, and good reproducibility. The assay correlates well with the CAP system and is in agreement with clinical diagnosis.