Extended IgE profile based on an allergen macroarray: a novel tool for precision medicine in allergy diagnosis

Abstract

BackgroundPrecision medicine (PM) is changing the scope of allergy diagnosis and treatment. An in vitro IgE assay, a prototype PM method, was developed in the sixties and has garnered increasing interest because of the introduction of recombinant components in the test. More recently, microarrays of allergen components have significantly improved the ability to describe the IgE profile. Aim of this study was to evaluate the characteristics of the newly developed Allergy Explorer (ALEX), a macroarray containing both extracted “whole” allergens and molecular components. This method allows the acquisition of an IgE profile comprising 282 reagents (157 allergen extracts and 125 components), resulting in the widest screening of potential allergens available.MethodsSera from 43 patients with allergies were assayed with ALEX and then with ImmunoCAP ISAC. The results of the two tests were compared, and the consistency of the molecular results with the presence of IgE in the relevant extract was also evaluated.ResultsA good correlation between ISAC and ALEX was observed. The ALEX results for second-level tests (i.e., specific IgE to complete extracted allergens) were consistent with the results obtained for the relevant components.DiscussionDespite differences in the methodology, the IgE profiles detected for molecular allergens by ALEX and ISAC were very similar. The differences were mainly related to the lower dynamic range of ALEX and to the use of a CCD inhibitor in the first incubation phase, which reduced the binding of IgE to CCD, as represented in the extracted allergens and components.ConclusionBased on our findings, ALEX is a novel tool for describing the IgE profile in a PM setting, where the IgE assay must be performed on many allergens and components. In particular, polysensitized patients and patients with pollen-food syndrome will have a real advantage due the combination of the second and third levels of allergy diagnostics in the same chip.

β‐1,3‐glucanase rOle e 9 and MnSOD rAsp f 6 IgE reactivity are the signature of atopic dermatitis in the Mediterranean area

“…The dedicated software digitalizes the images and prepares a report that lists the allergens and components and their score in kUA/mL. Finally, an arbitrary calibration curve is obtained by reacting four spots with decreasing concentrations of specific IgE corresponding to < 0.35, 0.35‐1, 1‐5, 5‐15 kUA/L and > 15 kUA/L . We considered as positive a concentration ≥ 0.35 kUA/L.…”

“…Finally, an arbitrary calibration curve is obtained by reacting four spots with decreasing concentrations of specific IgE corresponding to < 0.35, 0.35-1, 1-5, 5-15 kUA/L and > 15 kUA/L. 24,25 We considered as positive a concentration ≥ 0.35 kUA/L.…”

A WAO — ARIA — GA2LEN consensus document on molecular-based allergy diagnosis (PAMD@): Update 2020

“…Notably, analysis by multiplex assay may be even possible with a dried blood spot, which can be easily transported. 53 There are several commercially available immuno-solid-phase multiplex allergen arrays: the Thermo Fisher ImmunoCAP ISAC (Immuno-solidphase Allergen Chip), which contains 112 allergens from 51 allergen sources 12 ; the new ImmunoCAP ISAC 112i, with 112 components from 48 allergen sources, where some components have been removed (Hymenoptera components, Pla a 2, Jug r 2) and some others were added (Ana o 3, Can f 4, Can f 6, Cor a 14, Der p 23 and alpha-Gal); the MADx Allergen Explorer (ALEX; containing 282 allergens: 156 extracts and 126 components) 54 ; and the Euroline microstrips. 55 The large number of extracts/ allergens from multiple classes of allergenic sources (Table 2) provides extensive and detailed information about a patient's sensitization profile.…”

“…55 The large number of extracts/ allergens from multiple classes of allergenic sources (Table 2) provides extensive and detailed information about a patient's sensitization profile. 54,56 Other diagnostic tools based on allergen arrays are under development, and new tools will likely be available in the near future.…”

The WHO/IUIS Allergen Nomenclature

“…The identification of individual allergenic proteins has led to new diagnostic in vitro tests using purified recombinant molecules including Thermo Scientific's ImmunoCAP ISAC, INDOOR Biotechnologies’ MARIA, Centri Associati de Allergologia Moleculare's FABER, and Macro Array Diagnostics’ ALEX. Reports on results of such tests are increasingly presented at scientific and clinical meetings and in publications . A number of studies presented at the EAACI Food Allergy and Anaphylaxis Meeting 2018 described IgE‐binding to purified nonspecific lipid transfer proteins (nsLTP) from foods and aeroallergen sources using microarray chip presentation of pure proteins.…”