Comparison of specific IgE detection by immunoblotting and fluorescence enzyme assay with in vivo skin prick test

Abstract

Background: Diagnostic tools to identify allergens that cause allergic symptom is important part in the care of allergic patients. Detection of causative allergen can be performed by in vivo skin prick test (SPT) or in vitro tests for detection serum specific immunoglobulin E (sIgE). The common methods used are fluorescent enzyme assay and immunoblotting assay. Objective: We aim to evaluate performance of the two sIgE determination systems, immunoblotting assay (Euroline) and fluorescent enzyme assay (ImmunoCAP) in comparison with SPT. Methods: Two hundred and two participants with allergic diseases were enrolled. Sensitization to common allergens was identified using skin prick test and serum specific IgE assays with Euroline and ImmunoCAP. Both systems provide the result in the same unit and the same cut-off value (0.35 kUA/L). The specific IgE levels of 4 aeroallergens, 6 food allergens and 3 food allergen components were analyzed to evaluate the performance of both sIgE assays with SPT. Results: When compared with the result of SPT, ImmunoCAP has 63.9-93.2% agreement and Euroline has 68.4-86.2% agreement for allergen detection. Both sIgE assays have significant correlation in measuring sIgE of almost all allergens (r=0.626-0.901, p<0.001) except for dog. For food allergen components, both sIgE tests have outstanding correlation and agreement (r=0.816-0.952, p<0.001; agreement =87.0-92.9%, respectively). The receiver-operating characteristic curve analysis indicated slight discrepancy of both sIgE assays. Conclusions: Both sIgE determination systems demonstrate fair to good performance when compared to SPT depending on type of allergens. The two sIgE determination systems had favorable correlation and agreement.