Long-term clinical and immunological effects of allergen immunotherapy

Purpose of review The present review updates current findings on long-term clinical and immunological outcomes after cessation of allergen immunotherapy for allergic respiratory disease. Recent findings Recent studies have shown that allergen immunotherapy has sustained disease-modifying effects that persist for years after discontinuation. This is in contrast to the effects of antiallergic drugs that do not induce tolerance to offending allergens. Longterm effects of immunotherapy include a reduction in nasal symptoms, a decrease in the use of rescue medication and improvement in quality of life. These benefits are accompanied by immunological changes such as the induction of allergen-specific IgG antibodies with inhibitory activity for IgE-facilitated binding of allergen-IgE complexes to B cells. One study reported a reduction in the development of asthma in children with seasonal pollen-induced rhinitis. Summary Allergen immunotherapy induces clinical and immunological tolerance as defined by persistence of clinical benefit and associated long-term immunological parameters after discontinuation of treatment. These findings are largely confined to studies of subcutaneous and sublingual immunotherapy for seasonal pollinosis. Further studies are needed to address potential long-term clinical effects for other seasonal and perennial inhaled allergens in both children and adults, and to identify potential biomarkers of tolerance.