Component-specific immunoglobulin E in the diagnosis of allergic disease in childhood: more of the same or something more?

June 2007Although the alarming rate of increase in the prevalence of al-lergic disease and asthma in the last decades of the 20th century seems to have abated [1,2], allergic rhinitis, atopic dermatitis and asthma are by far the most common chronic diseases affecting children worldwide.Allergic disease in childhood is an end result of complex interactions between genetic factors and environmental exposures [3], leading to a phenotypical progression of symptoms, from food hypersensitivity and allergic eczema in the first year of life to respiratory disease (allergic asthma and rhinitis) in later years – a sequence of events aptly named “the allergic march” [4]. Each of these allergic manifestations may have its own clinical presentation and course as well as temporal progression, with some – for example cow’s milk hypersensitivity [5] and atopic dermatitis [6] – most likely to resolve in the preschool years, while others are more likely to persist. The hallmark of allergic disease is an immune system skewed towards a Th2 predominant phenotype, with increased production of immunoglobulin E and sensitization to environmental allergens (allergen-specific IgE). Increased levels of total serum IgE at birth and in early life have been associated with an increased risk for the development of persistent asthma [7,8] and atopic dermatitis [9]. Early sensitization and levels of sIgE to perennial respiratory allergens have been associated with increased risk of childhood asthma [10,11]. In the field of food allergy, quantitative measurements of sIgE in the serum of sensitized children cor-relate well with the risk of challenge-associated reactions [12,13], and decreases in this level over time seem to correlate with the resolution of the clinical reactivity [14]. Several factors have led to the availability and use of detailed maps of component- and even epitope-specific sensitization data for both research and clinical applications [15]. These include: advances in the identification, isolation and characterization of the specific component proteins eliciting hypersensitivity responses from various allergen sources [16-18]; molecular tools for rapid expression and mass production of recombinant replica of these protein components [16]; and the development of tools enabling the simultaneous measurement of quantitative sIgE to a large number of antigens in a relatively small serum sample using micro-arrays and recombinant technologies [19]. The aim of this review is to familiarize the reader with the state of the art in component- and epitope-specific diagnosis in allergic disease in childhood, as well as future prospects for novel therapeutic approaches incorporating these data.Peptide-specific diagnosis of food hypersensitivity