D1.89 - Qualitative comparison between Euroline Respiratory Profile and Phadiatop for the screening of airborne allergies

Multiplex tests, which allow the measurement of allergen-specific IgE (sIgE) responses to multiple extracts, have several advantages for screening airborne allergies. The Euroline Mediterranean Inhalation Profile (Euroimmun, Lübeck, Germany) is a line blot assay that enables the simultaneous detection of multiple allergen-sIgE responses to 20 airborne allergen extracts and cross-reactive carbohydrate determinants (CCDs) from a single serum sample. We aimed to determine the accuracy of the Euroline test for screening airborne allergies compared to the Phadiatop extract-based reagent (ThermoFisher Scientific, Uppsala, Sweden), which is considered the gold standard.

We conducted a retrospective, multicentre study involving 101 serum samples from 50 children and 51 adults who were undergoing screening for respiratory allergies between 2021 and 2024. sIgE levels were measured for m6, m2, e3, e2, e1, d70, d2, d1, w19, w9, w6, w1, t210, t23, t11, t9, t4, t3, g6, g2 and CCD using Euroline (DP 3112-1601 E) and ImmunoCAP (ThermoFisher Scientifics) platforms according to the manufacturer's recommendations. The correlation between Euroline and Phadiatop results was determined using the percentage of agreement and Cohen’s kappa coefficient.

We observed 55 positive concordant results, 20 negative concordant results and 26 discrepant results. All of these were positive in Euroline and negative in Phadiatop. None were positive for CCD. The qualitative comparison was moderate: the percentage of agreement was 75% and Cohen's kappa coefficient was 0.456 (95% Ci: 0.304 to 0.607). Analyzing the sIgE concentrations revealed low values between 0.35 and 0.52 kUA/L for 25 subjects close to the positivity limit. Only one had a m6 superior to 2.72 kUA/L. The observed discrepancies can be attributed to the varying compositions of the assays: they were positive for allergens that may not be included in Phadiatop, for which the precise composition remains unknown, such as Alternaria, horse dander, weed and privet and olive pollen particularly prevalent in the Mediterranean area.

The low concordance observed between the Euroline Mediterranean Inhalation Profile and the Phadiatop is likely explained by differences in allergen composition. An adapted panel appears relevant to better identify region-specific airborne sensitizations. These results warrant confirmation through a dedicated clinical study integrating environmental exposure data.