Allergen-Specific Immunotherapy in Asthma

Current asthma therapies can effectively control symptoms and the on-going inflammatory process; however, they do not affect the underlying, dysregulated immune response. Thus, they are limited to blunting the progression of the disease, which relapses on ceasing the treatment. Allergen-specific immunotherapy (AIT) is the only etiology-based treatment capable of disease modification. Recent evidence provided a plausible explanation for its multiple mechanisms inducing both rapid desensitization and long-term allergen-specific immune tolerance, as well as the suppression of allergic inflammation in the affected tissues. Although the current guideline documents give both subcutaneous (SCIT) and sublingual (SLIT) immunotherapy a conditional recommendation in allergic asthma due to the moderate and low quality of evidence, respectively, a growing body of evidence from double-blind, placebo-controlled studies shows that both SLIT and SCIT are effective in reducing symptom scores and medication use, improving quality of life, and inducing favorable changes in specific immunologic markers. Due to the very limited evidence from head-to-head comparative studies and variability of the end-point used in different studies, it is currently not possible to assess superiority of either route of vaccine administration.