One century of allergen-specific immunotherapy for respiratory allergy

Among the treatments available for respiratory allergy, which include allergen avoidance and pharmacotherapy, specific immunotherapy (SIT) is the only treatment able to not only act on the symptoms of allergy but also act on the causes. SIT is the practice of administering gradually increasing doses of the specific causative allergen to reduce the clinical reactivity of allergic subjects and was introduced one century ago. SIT remained an empirical treatment for more than 40 years, but the first controlled trial in 1954 paved the way for the scientific era. At present, SIT may be administered in two forms: subcutaneous (SCIT) and sublingual immunotherapy (SLIT). A large number of trials, globally analyzed in several meta-analyses, evaluated the efficacy and safety of SCIT and SLIT in allergic rhinitis and asthma. Current available data give solid evidence to the clinical efficacy of both SCIT and SLIT in allergic rhinitis and asthma. Providing the recommended doses and administration schedules are adhered to, the safety and tolerability are very good; however, adverse systemic reactions remain a drawback for SCIT. After one century of use, accumulating evidence surrounds SIT and the central role in the management of respiratory allergy.