Molekulare Allergiediagnostik im Multiplex-Verfahren: Teil 21 der Serie Molekulare Allergie

Microarray-Based Allergy Diagnosis: Quo Vadis?

More than 30% of the world population suffers from allergy. Allergic individuals are characterized by the production of immunoglobulin E (IgE) antibodies against innocuous environmental allergens. Upon allergen recognition IgE mediates allergen-specific immediate and late-phase allergic inflammation in different organs. The identification of the disease-causing allergens by demonstrating the presence of allergen-specific IgE is the key to precision medicine in allergy because it allows tailoring different forms of prevention and treatment according to the sensitization profiles of individual allergic patients. More than 30 years ago molecular cloning started to accelerate the identification of the disease-causing allergen molecules and enabled their production as recombinant molecules. Based on recombinant allergen molecules, molecular allergy diagnosis was introduced into clinical practice and allowed dissecting the molecular sensitization profiles of allergic patients. In 2002 it was demonstrated that microarray technology allows assembling large numbers of allergen molecules on chips for the rapid serological testing of IgE sensitizations with small volumes of serum. Since then microarrayed allergens have revolutionized research and diagnosis in allergy, but several unmet needs remain. Here we show that detection of IgE- and IgG-reactivity to a panel of respiratory allergens microarrayed onto silicon elements is more sensitive than glass-based chips. We discuss the advantages of silicon-based allergen microarrays and how this technology will allow addressing hitherto unmet needs in microarray-based allergy diagnosis. Importantly, it described how the assembly of silicon microarray elements may create different microarray formats for suiting different diagnostic applications such as quick testing of single patients, medium scale testing and fully automated large scale testing.

Diagnostic precision of component-resolved vs. extract-based in vitro diagnosis of hymenoptera venom allergy: effects on clinical management

BACKGROUND

The measurement of specific IgE (sIgE) antibodies plays a key role in the diagnosis of honeybee and wasp venom allergy. In recent years, component-resolved diagnosis (CRD) has been introduced, which allows for the measurement of sIgE antibodies against Api m 1, Ves v 1, Ves v 5, and Pol d 5, as well as cross-reactive carbohydrate determinants (CCDs). These tests are intended to help determine the clinical relevance of any given sensitization, especially in patients with dual sensitization.

PATIENTS AND METHODS

Specific IgE antibody levels were measured in 143 patients with bee and/or wasp venom allergy using the extract-based ImmunoCAP^® allergens i1 and i3 as well as the ImmunoCAP^® allergen components i208-211 and O214 (Api m 1, Ves v 1, Ves v 5, Pol d 5, CCDs). In patients with dual sensitization, inhibition testing was also performed. In a subgroup of the study population, sIgE to Api m 1, Api m 4, Pol d 5, and Ves v 5 were determined using the ISAC^® allergy microarray (n = 44).

RESULTS

The sensitivity of Ves v 5 in patients with isolated wasp venom allergy was 78.5 %; in combination with Ves v 1, that figure increased to 92.3 %. The sensitivity of Api m 1 in individuals with isolated bee venom allergy was 25 %. CRD and inhibition testing in individuals with dual sensitization showed divergent results. CRD using the ISAC^® allergy microarray showed marked differences, especially with regard to Api m 1 and CCDs.

CONCLUSION

Component-resolved tests are a valuable addition to the diagnostic spectrum as long as they are used in combination with established procedures. Apart from Ves v 5, measuring IgE antibodies to Ves v 1 should always be included in the diagnostic workup.