ImmunoCAP ISAC E112i (ISAC) and Allergy Explorer 2 (ALEX²) detect specific immunoglobulin E (IgE) reactivity. Both multiplex assays contain molecular allergens and ALEX² additionally includes allergen extracts and inhibitors that block the binding of IgE to cross-reacting carbohydrate determinants (CCDs). This study aimed to compare the performance of ISAC and ALEX² by determining the IgE reactivity against allergen extracts and/or allergen components and by using qualitative, semiquantitative, and quantitative analyses of all comparable allergen components in sera from 216 participants recruited in South Tyrol/Italy. For extract sensitization in ALEX², the analysis revealed negative corresponding allergen components in 18.4% and at least one positive corresponding allergen component in 81.6% of all cases. For ISAC, the corresponding results were 23.5% and 76.5% of cases, respectively. The ALEX² CCD inhibitor eliminated CCD-positive signals detected by ISAC in 88.5% of cases. Based on sensitization values of 0.3–14.9 ISU or kU_A/L, there was good agreement between ALEX² and ISAC, although ALEX² showed higher values than ISAC. The addition of allergen-extract tests in ALEX² resulted in the detection of more sensitizations than with corresponding allergen components alone. In the range of <15 ISU or kU_A/L, ALEX² may be more effective in detecting sensitizations.

Zusammenfassung: Hintergrund und Zielsetzung: Panallergen‐Familien sind unterschiedlich hitze‐ und pH‐stabil, was sich auf Intensität und Charakteristika allergischer Reaktionen auswirkt. Das Ausmaß einer Epithelbarriere‐Dysfunktion beeinflusst maßgeblich die Sensibilisierung gegen verschiedene Allergene. Das Ziel unserer Studie war es, Zusammenhänge zwischen Patientenmerkmalen, Markern der epithelialen Barriere und unterschiedlichen Sensibilisierungsprofilen zu entschlüsseln. Patienten und Methodik: Spezifisches Immunglobulin E (sIgE) gegen stabile (2S‐Albumine, 7/8S‐ und 11S‐Globuline) und unstabile Allergene (PR‐10‐Proteine, Profiline) wurde bei 216 rekrutierten Patienten aus Südtirol, Italien, mit dem Multiplex‐Assay ALEX ² bestimmt und mit demografischen Daten der Patienten, allergischen Symptomen, dem Investigator Global Assessment Score (IGA Score), dem transepidermalen Wasserverlust (TEWL) und dem fraktionierten exhalierten Stickstoffmonoxid (FeNO) korreliert. Ergebnisse: Patienten mit Sensibilisierungen gegen stabile Allergene waren jünger, wiesen häufiger Ekzeme, höhere IGA‐Werte und einen höheren TEWL auf. Gastrointestinale Symptome in Kombination mit Hautsymptomen traten häufiger auf. Respiratorische Symptome allein traten bei Patienten mit Sensibilisierungen gegen unstabile Allergene häufiger auf, korrelierten aber nur mit höheren FeNO‐Werten im Falle von Ko‐Sensibilisierungen gegen stabile Allergene. Schlussfolgerungen: Sensibilisierungen gegen stabile Allergene sind mit ausgeprägter Beeinträchtigung der Epithelbarriere verbunden. Kinder mit Atemwegssymptomen könnten von der Testung mit Multiplex‐Tests auf Ko‐Sensibilisierungen gegen stabile Nahrungsmittelallergene und von der frühzeitigen Einleitung einer spezifischen Immuntherapie gegen Aeroallergene profitieren, um in positiven Fällen eine Asthmaentwicklung zu verhindern.

Summary: Background and Objectives: Panallergen families differ in their stability to heat and pH, which affects both the severity and clinical manifestations of allergic reactions. The extent of epithelial barrier dysfunction is thought to influence sensitization to different allergens. This study aimed to investigate associations between patient characteristics, epithelial barrier‐related markers, and distinct sensitization profiles. Patients and Methods: Specific immunoglobulin E (sIgE) against stable (2S albumins, 7/8S and 11S globulins) and unstable allergens (PR‐10 proteins, profilins) was assessed in 216 patients recruited in South Tyrol, Italy, using the multiplex assay ALEX ² and correlated with patient demographics, allergic symptoms, Investigator Global Assessment Score (IGA score), Transepidermal Water Loss (TEWL), and Fractional exhaled Nitric Oxide (FeNO). Results: Patients sensitized to stable allergens were younger, showed more frequently eczema, higher IGA scores, and higher TEWL. Gastrointestinal symptoms combined with skin symptoms were more common. Respiratory symptoms alone were more frequent in patients sensitized to unstable allergens but were associated with higher FeNO values only in the case of co‐sensitizations to stable allergens. Conclusions: Sensitization to stable allergens is associated with distinctive epithelial barrier impairment. Children with respiratory symptoms may benefit from multiplex testing for co‐sensitizations to stable food allergens and early initiation of specific immunotherapy to aeroallergens to prevent asthma in positive cases.

Background: The increasing prevalence of allergic diseases, along with their diagnosis and treatment, presents a growing challenge in health care. To reduce this burden, a highly sensitive and specific point-of-care test for detecting sensitization could be implemented in a primary health care setting. The study aimed to investigate the accuracy of FastCheckPOC 20 Atopy (FCP20) in comparison with the multiplex assay Allergy Explorer 2 (ALEX ² ) system. Methods: In this cross-sectional study, 215 participants were recruited from South Tyrol, Italy. Serum samples were analyzed using both FCP20 and ALEX ² . Dichotomous data were used to calculate sensitivity and specificity in comparison with the ALEX ² . Results: The overall sensitivity of the FCP20 was 43.3% (95% CI: 40.3%–46.2%), and the specificity was 92.1% (95% CI: 91.1%–93.0%). Inhalation allergens showed a higher sensitivity than food allergens; the grass pollen (gx17) exhibited the highest sensitivity at 79.8% (95% CI: 72.6%–85.7%). Among patients with severe allergic symptoms, bronchial asthma, or eczema, sensitivity increased to over 83%. Conclusions: FCP20 demonstrates high specificity and may be considered for the exclusion of sensitization to selected allergens, but its low sensitivity limits its utility as a general screening tool.