Comparative study of Allergy Explorer (ALEX) versus ImmunoCAP platforms

Objective. In this study, technical performance of the new multiplex ALEX test was compared with results from ImmunoCAP single tests (tIgE, sIgE) and the multiplex platform ImmunoCAP ISAC sIgE 112. Materials and methods. Eleven whole allergen extracts and corresponding allergen components from different allergen groups were used for the analysis of 64-66 patients’ sera by all three platforms. Results. For the whole allergens, 55% false negative results were obtained with the ALEX test comparing to the ImmunoCAP sIgE tests while for allergen components the ALEX test gives 33% false negative results when compared to ImmunoCAP sIgE test results. Additionally, the ALEX test is characterized by a low dynamic range - the platform demonstrated no results above 36 kUA/L for samples giving >100 kUA/L using ImmunoCAP Specific IgE tests in the analysis of sIgE response to the whole allergens. For the allergen components, ALEX showed no results above 38 kUA/L for samples of up to 150 kUA/L according to ImmunoCAP Specific IgE test results. Comparing to ImmunoCAP single plex tests, ALEX show low dynamic range and poor agreement in quantitative results for tIgE and sIgE both for whole allergens and allergen components, while in the comparison with ImmunoCAP ISAC sIgE 112 platform, the agreement is better, but the sensitivity and dynamic range are still low._ Conclusions. The ALEX test has some serious limitations in its performance comparing to both types of ImmunoCAP platforms.