A qualitative and quantitative comparison of IgE antibody profiles with two multiplex platforms for component‐resolved diagnostics in allergic patients

Abstract

Background Clinically complex phenotypes require more and more sophisticated and comprehensive diagnostic approaches, able to discriminate genuine sensitizations from cross‐reactivity. Interpretative complexity of multiplex diagnostic arrays has somewhat limited their diffusion. This study compares two currently available methods, namely ISAC® test and ALEX2® test. Methods In total, 140 allergic individuals, with a history of atopic dermatitis, adverse food reactions, allergic rhinitis and/or bronchial asthma were studied by Allergy Explorer‐ALEX2® macroarray and ImmunoCAP ISAC112®. Lin's concordance correlation coefficient, intraclass correlation coefficient and Bland–Altman plots were used to verify the agreement between continuous values. Cohen's kappa coefficient (k) was assessed for the molecules available in both tests. The degree of relationship was analysed using Spearman's correlation (quantitative variables) and Pearson's χ2 or Fisher's exact test (categorical variables). Results A substantial agreement (κ = 0.795) was observed between the two methods with 94,3% concordant results when results were dichotomized as negative or positive, but if double‐negative results were discarded, the agreement dropped to 71%. Conversely, little or no concordance was observed comparing raw data. Considering the 102 molecules shared by both systems, 28/102 (27%) showed an almost perfect agreement (k > 0.81), and concordance was good (k > 0.61) in a further 32 (31%) cases. A perfect to substantial agreement was observed by comparing species‐specific aeroallergens. Heterogeneous results emerged comparing panallergens (co‐recognition ranging from 30% for tropomyosin/serum albumins to 70% for PR‐10/profilin). The correlation among LTP, profilin and PR‐10 assayed with ISAC® was better than ALEX2®, but the latter identified more positive cases due to the wider number of molecules available. The CCD blocker provided by ALEX® test abolishes the carbohydrate determinants signal in 60% of the 33 cases reactive to MUXF3 on the ISAC® test. Conclusion Despite the excellent concordance of the species‐specific markers, the analysis of the panallergens provided in both methods suggests a better performance of the ISAC® test on those components, while the ALEX2® test, which includes a larger number of allergens, allowing a broader molecular detection.

Mollusk allergy in shrimp-allergic patients: Still a complex diagnosis. An Italian real-life cross-sectional multicenter study

“…In a subset randomly selected (98 individuals, 48 from North Italy and 50 from Center-South Italy) a more in-depth evaluation was carried out by the Allergy Explorer-ALEX2Ò (Macroarray Diagnostics, Vienna) multiplex platform evaluating a broader profile of shellfish molecules, 13 including Pen m 1 (tropomyosin), Pen m 2 (arginine kinase), Pen m 3 (myosin light chain), and Pen m 4 (sarcoplasmic calcium-binding protein) all from Black-Tiger shrimp (Penaeus monodon), Cra c 6 (the troponin-c from brown shrimp, Crangon crangon), Der p 10 (tropomyosin), and Der p 11 (paramyosin) both from Dermatophagoides pteronyssinus, as well as of shellfish extract including crab, lobster, northern shrimp, white shrimp, squid, mussel, oyster, clam, and scallop. IgE levels >0.3kUA/L were considered positive as per the manufacturer's instructions.…”

Lipid transfer protein allergy: A review of current controversies

“…This has made it possible to investigate novel molecular recognition profiles. 91 By comparing one another the structural identity of these molecules, it is possible to observe how these form clusters that largely depend on their botanical origins and phylogenetic relationships. For instance, the 2 nsLTPs of 7 kD form a cluster, as do grape (Vitis vinifera) nsLTP, Vit v 1, and hemp (Cannabis sativa) nsLTP, Can s 3, or apple (Malus domestica) Mal d 3 and Pru p3 (Figure 2).…”

“…Recently, additional nsLTP molecules, showing a molecular weight of either 7 kDa or 9 kDa, have become available for in vitro diagnostics by multiplex tests. This has made it possible to investigate novel molecular recognition profiles 91 …”

ALEX versus ISAC multiplex array in analyzing food allergy in atopic children

“…ALEX and ISAC share 102 common inhalation-and food-derived allergen components. Previous studies [1][2][3][4] showed good agreement between ALEX and ISAC, however none of these studies related both their sensitization results directly to clinical relevant allergies, neither discussed the impact on clinical decision making in children with food allergy.…”

“…Both ALEX and ISAC are solid-phase immunoassays which enable the detection of sIgE to multiple individual allergen components. When comparing these multiplex arrays one should be aware that both platforms employ different methodologies and units of measurement [5], and in addition ALEX uses a CCD inhibitor while ISAC does not [1][2][3]5]. ALEX reports its results as kUA/L, similar as Immu-noCAP, classified in five different categories (Fig.…”