Egg white component-resolved diagnosis: Testing of serum ovalbumin-specific IgE by luminescent oxygen channeling immunoassay

Egg allergy is the second most common food allergy in children. Precise measurement of allergen component-specific IgE (sIgE) in serum contributes to molecular diagnosis of egg allergy, i.e. component-resolved diagnosis (CRD). Existing CRD methods, including ImmunoCAP and Immulite, have unavoidable drawbacks such as errors from solid-liquid phase separation and enzyme instability. Therefore, we take egg allergen ovalbumin as an example to establish a homogenous method−indirect luminescent oxygen channeling immunoassay (LOCI) to determine ovalbumin-sIgE precisely. In the indirect LOCI reaction system, ovalbumin-conjugated acceptor nanoparticles were brought close to streptavidin-conjugated donor nanoparticles through antigen-antibody and biotin-streptavidin interactions. The optimal conditions for LOCI were 16.67 μg/mL acceptor-ovalbumin, 1.047 μg/mL biotinylated anti-human IgE antibodies and a 1/20 dilution of serum in a 25-μL reaction volume for a 45-min incubation. We assessed the performance of of this LOCI system, including sensitivity, precision, and anti-interference ability, and compared the diagnostic performance of the LOCI with enzyme-linked immunosorbent assay (ELISA) through a receiver operator characteristic (ROC) analysis. Results revealed that LOCI was superior to ELISA in performance. In summary, we demonstrated that indirect LOCI was an excellent method for precise determination of allergen component-sIgE, contributing to CRD of food allergy.