The crux with a reliable in vitro and in vivo diagnosis of allergy

This might be due to different reasons. Allergen-specific IgE in serum is a marker for sensitization and a prerequisite for the development of an allergy but is not sufficient for the induction of symptoms. We should be aware that all in vivo and in vitro tests are subject to inherent variation and potential interferences. In patients with symptoms suggestive of allergic rhinitis but negative results in skin test and serum soluble IgE, detection of local soluble IgE in nasal secretions during natural exposure to aeroallergens and a positive nasal allergen provocation test might explain the symptomatics 14. As discussed by Aalberse et al. 5 and reported elsewhere, there are good indications that recombinant allergens could be more efficient for the in vitro and in vivo diagnosis of allergy than extracts 15. Recombinant allergens can be produced as GMP pharmaceuticals satisfying the quality requirements for medical use 15, and technologically, it is straightforward to generate microarrays containing hundreds of different allergens 9. The concept of a component resolved diagnosis of allergy is not new but the problem is, as pointed out by Aalberse et al. 5, how to validate its clinical relevance. Even if the production of a microarray containing an optimal panel of perfectly standardized recombinant allergens is technically possible to date, which can contribute to improve the in vitro diagnosis of atopy in terms of sensitivity and specificity, it will still generate false-positive and false-negative results concerning the diagnosis of allergy. Thus, the allergologist should be prudent in judging the outcome of any in vivo or in vitro test that is inconsistent with a carefully collected clinical history, especially if patients are considered for inclusion in allergen-specific immunotherapeutic treatments. At the current state of the art, it is worthwhile to maintain a healthy scepticism about allergy diagnostic test results and to let the clinical history drive the diagnosis. The laboratory of the author is supported by the Swiss National Science Foundation grants No. 3200_146247 and 32NM30_136032/1 (EuroNanoMed) and by the European Community's Seventh Framework Program [FP7-2007-2013] under grant agreement no. HEALTH-F2-2010-260338 'ALLFUN'. The author has no conflict of interest relevant to this article.