Conclusion & Future Perspective
The clinical efficacy of SCIT is well established for both rhinitis and asthma. Meta-analyses relating to its efficacy on asthma[28] and rhinitis[20] are available. SLIT has also been validated in this respect.[12] Two recent meta-analyses in children showed that sublingual delivery of allergen vaccination constitutes a safe and effective alternative to the injectable route to reduce allergic respiratory symptoms and drug intake.[30,111] Assessment of possible long-term benefits, including long-term disease remissions, suppression of new allergic sensitizations, and reduction of progression from rhinitis to asthma in children, as has been shown for the subcutaneous route, are future requirements.
The immunological effects of SLIT and how these relate to clinical efficacy are yet incompletely understood. Large-scale trials have confirmed the induction of allergen-specific IgG antibodies to be dose dependent. There is no early suppression of allergen-specific IgE antibodies and a transient early increase in specific IgE antibodies as in SCIT.
Current models of SCIT propose the induction of antigen-specific Tregs, which then orchestrate the observed antibody and mucosal changes observed during treatment. As of yet there is only scarce evidence that such mechanisms operate during SLIT. Comparative clinical studies of sublingual and subcutaneous treatment yielded heterogeneous results demonstrating efficacy of both modes, but SLIT to be a safer approach.[105,107,108]
In conclusion, understanding of the interaction of allergen and antigen-presenting cells within the oral mucosa may allow improved targeting of SLIT vaccines. In the near future the combination of allergen products with adjuvants may improve efficacy of immunotherapy via the sublingual route.
Financial & competing interests disclosure
The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.
No writing assistance was utilized in the production of this manuscript.
Immunotherapy. 2011;3(6):747-756. © 2011 Future Medicine Ltd.
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