Development of a light-initiated chemiluminescent assay for the quantitation of sIgE against egg white allergens based on component-resolved diagnosis

The determination of specific IgE (sIgE) level is of great importance in IgE-mediated food allergies. Our aim was to develop a homogeneous immunoassay-light-initiated chemiluminescent assay (LICA)-for measuring allergen sIgE of a single component in egg white, thus evaluating the LICA-sIgE assay as a useful tool in the diagnosis of food allergy. The LICA-sIgE assay was performed by incubating serum sample with anti-human IgE antibody coated with chemiluminescer beads, streptavidin-coated sensitizer beads, and biotinylated antigens, which consist of four components in egg white. Serum samples from egg allergic patients (n = 70) and healthy volunteers (n = 30) were collected. For calibration, purified human IgE was used as the calibrator. Working conditions of this homogeneous immunoassay were optimized, analytical performance was determined, and correlation of the results between LICA and ImmunoCAP was evaluated. The assays were performed in 8-well plates with a sample volume diluted to 1:10 of 25 mu l. Intra-assay precision (% coefficient of variation) ranged from 1.83 to 4.13%, and inter-assay precision ranged from 2.70 to 8.70%. It exhibited excellent sensitivity, which could distinguish between positive samples and negative samples even at a large dilution level. The sIgE-LICA and ImmunoCAP correlated well in patients allergic to single component (r (2) = 0.929). Also, the components ovomucoid and ovalbumin were best at predicting ImmunoCAP results, with the same area under the ROC curve (AUC) of 0.81, and a specificity of 90.0 and 93.3%, respectively. Our data show effective performance characteristics of LICA to detect sIgE in human serum based on component-resolved diagnostic tests (CRD). The homogeneous sIgE-LICA assay has the following key advantages: requires no washing, simplicity and rapidity, reproducibility, high-throughput, good performance in a liquid phase assay, and good suitability for sIgE diagnosis in food allergy based on CRD.