Molecular Aspects of Allergen-Specific Immunotherapy in Patients with Seasonal Allergic Rhinitis

A systematic review and narrative synthesis of publications was undertaken to analyze the role of component-resolved diagnosis technology in identifying polysensitization for the provision of allergen-specific immunotherapy to patients with seasonal allergic rhinitis. A search of publications was carried out in electronic databases in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The search helped to identify 568 publications, 12 of which were included in this review. Overall, 3302 patients were enrolled. The major finding was that component-resolved diagnostics change the choice of relevant allergens for allergen-specific immunotherapy in at least 50% of cases. Sensitization to allergen components differs with age, type of disease, and overall disease duration. Patients who had both bronchial asthma and allergic rhinitis were sensitized to a larger number of allergens than patients who had bronchial asthma alone.

A comprehensive comparison between ISAC and ALEX2 multiplex test systems

OBJECTIVES

Diagnosis of type I hypersensitivity is based on anamnesis, provocation as well as blood- and skin testing. Multiplex specific IgE (sIgE) testing enables determination of sIgE antibodies against multiple recombinant or purified natural allergen components. The aim of this study was to evaluate the performance of the novel ALEX^2® (Allergy Explorer, ALEX² test introduced on the market November 2019) multiplex platform and to compare it with the ImmunoCAP ISAC^® test system.

METHODS

Serum samples of 49 patients, routinely determined with ISAC, were selected based on positive results covering in total most of the 112 ISAC components. Cohen's kappa, negative percent agreement (NPA), and positive percent agreement (PPA) of ALEX² data compared to ISAC data (as a non-reference standard) were computed for those allergen components present on both platforms (n=103). Furthermore, in some samples sIgE results against allergen extracts and/or -components tested with either ImmunoCAP^® (ThermoFisher) or IMMULITE^® (Siemens) were available and compared to ALEX² results.

RESULTS

The overall agreement between ISAC and ALEX² common allergen components was 94%. NPA and PPA were respectively 95 and 90%. Kappa values differed for specific allergen groups and varied between 0.60 and 0.92 showing moderate to almost perfect agreement. Of the qualitative discrepancies between ALEX² and ISAC, 59% were related to weak positive results i.e. results under 1 kUA/L or 1 ISU, respectively.

CONCLUSIONS

The method comparison between ISAC and ALEX² multiplex tests showed a high concordance for those allergen components present on both platforms.

Molecular Allergy Diagnostics as an Adjunct to Conventional Diagnostics in a Secondary Pediatric Referral Center

Background:

Several compositions for determination of specific molecular components in allergens have recently been patented. The role of Molecular Allergy (MA) diagnostics in suspected IgE mediated allergic conditions is currently debated. Guideline reports have concluded that population-based studies involving evaluation of the usefulness of MA diagnostics are needed.

Objective:

To evaluate the usefulness of MA diagnostics in a secondary pediatric referral center.

Methods:

A total of 961 children and adolescents aged 0.2-18.8 (mean 7.0) years was included in a pro-spective observational survey. Inclusion criterion was a suspected diagnosis of an IgE mediated condition based on history and clinical symptoms and signs. If a specific diagnosis could not be reached from con-ventional investigations suspected peanut allergy, birch pollen allergy and associated cross-reactivity, insect allergy and triggering allergens for specific immunotherapy were assessed by MA diagnostics.

Results:

Based on conventional work-up a diagnostic conclusion was established in 946 patients (98.4%). MA diagnostics were performed in 15 individuals (1.6%), 7 girls and 8 boys aged 3.2 to 17.8 (mean 10.6) years. In 8 cases a specific diagnosis was established based on MA diagnostics; in 7 cases MA diagnostics could not improve diagnosis. MA were most frequently (N = 7 (14%)) used in children with peanut allergy (N = 50).

Conclusion:

Most patients in a secondary pediatric referral center with suspected IgE mediated allergy can be managed by conventional diagnostic methods. MA diagnostics may be useful in small and selected subgroups as in patients with suspected peanut allergy, however, may not be helpful in all cases.

Spiking with recombinant allergens to improve allergen extracts: benefits and limitations for the use in routine diagnostics: Part 19 of the Series Molecular Allergology

Essentially, allergen components offer three possibilities to improve in vitro IgE diagnostics:

Allergen components can be used individually for IgE determination.

Allergen components can be combined as a mix in one test.

Individual allergen components can be specifically added to the extract.

Option (a) is currently being used most extensively in practice, while (b) represents more of a theoretical possibility. The specific addition (“spiking”) of allergen components to an allergy extract (c) has been performed in the past for the ImmunoCAP® tests for latex (09/2001), hazelnut (05/2006) and wasp venom (06/2012). Through this approach under-represented allergen components could be compensated and the analytical sensitivity of the test systems significantly increased. In combined use with molecular Singleplex tests, these modified tests allow for new diagnostic possibilities. Clear communication from the manufacturer regarding in which test and from what time point on, recombinant allergens were added – and where this was not done despite under-represented allergen components – is important for the interpretation of the test results in routine clinical practice.