<i>IN VITRO</i> ALLERGY DIAGNOSIS: A COMPARATIVE ANALYSIS OF IgE SPECIFIC TO THE INHALANT ALLERGENS, OBTAINED BY IMMULITE AND PHADIA ASSAY SYSTEMS

Abstract

Allergen-specific diagnostics is carried out on the basis of the data collection from the patient’s family and personal history, skin test results, provocative tests and laboratory research methods. Methods for determining specific IgE antibodies (sIgE) play a key role in confirming the diagnosis and identifying the pathogenetic mechanism of an immediate-type hypersensitivity to an allergen. The purpose of the study was to evaluate the results of determining sIgE for allergens of cat epithelium, house dust mite D. farinae and birch pollen in the blood serum of patients suffering from respiratory allergy, by comparing two methods of ImmunoCAP Phadia and 3gAllergy Immulite, as well as determining whether the results of these test systems are in concordance with the results of skin tests in the patients. The serum samples were obtained from patients of St. Petersburg adult outpatient clinics, who suffered from respiratory allergies (n = 50). The samples were analyzed in parallel in two laboratories, with each of the laboratories using single test systems. The retrospective skin test results were obtained from twenty six of the fifty selected patients. The inter-method comparison was conducted by determining the concordance of positive and negative results, correlation and regression analysis of sIgE results for each allergen and ROC-analysis to compare the diagnostic specificity and sensitivity of test systems in relation to the results of skin tests. This study showed that, in terms of agreement and contingency of the results, the Immulite test system had a close relationship with the Phadia test system. Both analysis of classes and quantitative sIgE analysis showed a good positive correlation from 0.79 to 0.99 (p &lt; 0.0001) between the two test systems for all three allergens. High accuracy of coincidence in terms of sensitivity, area under the ROC curves (AUC) and cut-off threshold in both test systems was obtained for the D. farinae allergen. For allergens of cat epithelium and birch pollen, some differences between test systems were observed, i.e., sensitivity and AUC values were significantly higher in Immulite than in Phadia assay for both allergens.Thus, the inter-method comparison gave almost equivalent binary and quantitative results of the determination of sIgE antibodies to cat, tick and birch allergens. Comparison of in vitro test results, and their correlation with skin tests showed that the cat and birch in vitro antibody testing with Immulite assay was more closely connected with skin test results, than Phadia assay system.