Allergen immunotherapy today - sublingual or subcutaneous?

IT is potentially dangerous, especially when administred by nonspecialists, inexperienced in treating anaphylaxis. In search of new forms of IT which are more effective, easy to administer and safer, there has been a resurgence of interest in the local administration of high dose of allergen. In the 90s, many new double-blind placebo-controlled (DBPC) studies demonstrated a clinical benefit of some routes of local allergen vaccine. New techniques in immunology allowed to show some improvement of objective study parameters beside subjective benefit after sublingual allergen administration. It has been advocated that high-dose sublingual-swallow IT for respiratory allergy as well as nasal IT for allergic rhinitis may be viable alternatives to parenteral IT. However, the magnitude of improvements in symptoms and medication requirements after sublingual compared to standard injection IT has not been assessed. Injection IT has been shown to modify the natural course of the allergic disease. It prevents development of new sensitization and. reduces incidence of subsequent asthma. This has not been demonstrated for sublingual IT. There are no long-term follow-up studies after discontinuation of sublingual IT and not enough evidence to compare its clinical benefit with the effect of standard injection IT. Furthermore, analysis of studies assessing only children does not suggest that sublingual IT is of benefit for allergic respiratory disease in children. Many questions regarding the optimal dose of allergen administration, immunological changes as well as patient selection for sublingual IT, remain to be answered before this form of IT can be recommended for use in clinical practice.