Monitoring Allergen Immunotherapy Effects by Microarray

During the last decades, the prevalence of IgE-associated allergies increased worldwide, affecting currently millions of patients, some of whom suffering from severe or even life-threatening conditions [ 1 – 7 ]. Analysis of approximately 6500 sera from population-based European birth cohorts in the course of the MeDALL project [ 8 ] indicates an even higher percentage of sensitized children which most probably will lead to higher prevalence of allergic disease in the decades to come. Symptomatic medications like antihistamines, mast cell stabilizing agents, leukotriene receptor antagonists or, in more severe cases, corticosteroids or anti-IgE antibodies only have short-term effects and need to be administered regularly which causes considerable costs and burden to the patients due to adverse effects of the drugs. Allergen immunotherapy (AIT) is a cost-effective therapy and, so far, the only treatment that can yield sustained symptomatic improvement [ 9 ]. However, there are several factors that may hamper clinical efficacy of AIT, some of which are directly associated with the use of allergen extracts for vaccination. Due to the great variability of natural allergen sources regarding allergen composition and concentration, allergen extracts used both for diagnosis and therapy show considerable variation when products from different producers or different batches are compared [ 10 – 14 ]. In addition, specimens from particular allergen sources may contain clinically relevant allergens but their amounts are insufficient, e.g., Der p 23 from house dust mite [ 15 ], or are in general difficult to extract, like material from fungi [ 16 , 17 ]. Therefore, vaccines for AIT that are based on natural allergen extracts often do not cover the individual sensitization profile of the patient in terms of allergen composition and thus, treatment may fail in such cases. However, even if the vaccine does contain all clinically relevant allergen molecules it is not possible to predict for the individual patient if AIT is likely to induce a beneficial immune response because certain allergens may exhibit low immunogenicity and/or there may be non-responders among patients.