Allergen-Specific Immunotherapy

Allergic rhinitis is common and not always well controlled by standard drug therapies. Allergen-specific immunotherapy (SIT) is an effective treatment for allergic rhinitis and allergic asthma, but to achieve maximum sustained efficacy, a minimum of 3 years’ treatment is needed. SIT was first developed at the beginning of the 20th century, before elucidation of the underlying mechanisms of allergic disease. Nonetheless, the principles of SIT remain valid today. SIT induces changes in allergen-specific T cells, leading to a decreased responsiveness on allergen exposure. Symptoms following natural exposure to allergens are decreased but not always abolished. After a 3-year regimen, the clinical benefits of SIT persist after discontinuation. There is some evidence that SIT alters the development of allergic disease, which may lead to increased use of SIT in children in future years. Several approaches have been tried to improve the safety and convenience of SIT. Sublingual SIT (SLIT) is increasingly popular and carries benefits in terms of greater safety and convenience compared with injection SIT.