A light-initiated chemiluminescent assay for rapid quantitation of allergen-specific IgG in clinical samples.

Background: An increase in allergen-specific IgG (sIgG), which serves as a blocking antibody, is associated with acquisition of immune tolerance after immunotherapy. In this study, we developed a rapid, sensitive, and homogeneous immunoassay based on the light-initiated chemiluminescent assay (LICA) technology for quantifying allergen sIgG in serum samples.

Methods: Allergen sIgG was measured in vitro by incubating the sample with biotinylated allergens and chemiluminescent beads coated with anti-human IgG antibody, followed by the addition of streptavidin-coated sensitizer beads. Multiple tests were performed to optimize the working conditions of the LICA and evaluate its performance.

Results: We established the optimal concentration of biotinylated allergens (250 ng/mL), the optimal dilution range (1:8 for Gal d 1, Gal d 2 sIgG and 1:4 for Gal d 3, Gal d 4 sIgG), and the optimal incubation time (20 min for Gal d 1, Gal d 2 sIgG and 40 min for Gal d 3, Gal d 4 sIgG). The lower limit of quantification (LLOQ) was 0.261 ng/mL. The coefficient variation (CV) of the LICA was <10%. The assay was unaffected by general interfering substances at physiological concentrations. It exhibited excellent accuracy to detect allergen-sIgG in human serum. Additionally, we demonstrated that the levels of Gal d 1, Gal d 2, and Gal d 3-sIgG were significantly higher in the egg allergy group (p < .05), but no differences were found between the groups for Gal d 4-sIgG.

Conclusions: The LICA demonstrated satisfactory performance and can be used for quantifying allergen sIgG in clinical practice.