Allergen-specific immunotherapy for inhalants allergens in children

Allergen-specific immunotherapy (AIT) for aeroallergens consists of the administration of standardized allergen extracts to patients with respiratory IgE-mediated diseases to the same allergen in order to achieve immune tolerance to the allergen and prevent onset of symptoms. AIT is usually delivered by sublingual, subcutaneous route. Both sublingual immunotherapy (SLIT) and subcutaneous immunotherapy (SCIT) are given at increasing doses in the build-up phase and then at maintenance dose. The allergen dose is regularly administered throughout the year or pre/co-seasonally, depending on the causal allergen and the type of allergen extract. AIT with one or multiple allergens currently represents the only causal treatment able to change the natural history of allergic airways diseases (1). Significant progresses have been made in terms of AIT efficacy and safety since the first report of the treatment of hay-fever by SCIT using pollen extracts, described by Noon and Freeman in 1911 (2; 3). The first randomized study on SLIT dates back to 1986 (4). Several placebo-controlled studies on AIT in the subsequent years have allowed systematic reviews suggesting evidence for improvement of symptoms and reduction of medication use for both allergic rhinitis (AR) and asthma (5). However, AIT remains underused since interpretation of evidence remains challenging for heterogeneity among studied populations, selection of potential responders, outcomes, regimens and products for AIT. Moreover, the use of AIT is hampered by fluctuating availability of AIT products, different educational level of physicians and lack of consciousness of AIT in the general population (6).