New Insights into Immunotherapy for Allergic Disorders
Sublingual Immunotherapy for the Prevention and Management of Pediatric Asthma
Allergy and Respiratory Diseases
Department of Internal Medicine
University of Genoa
Giovanni Passalacqua, G. Walter Canonica
Allergy and Respiratory Diseases, Dept of Internal Medicine, University of Genoa, ITALY
The clinical efficacy of sublingual immunotherapy (SLIT) has recently been confirmed in several meta-analyses and large randomized controlled trials. The safety profile has also been confirmed to be satisfactory in both clinical trials and post-marketing surveys. Moreover, there is convincing evidence that the mechanisms of action of SLIT are partially similar to those of injection immunotherapy. In particular, SLIT is capable of inducing the production of IL-10 from regulatory T cells, thus modifying the balance between Th1 and Th2 lymphocytes (1).
Concerning the clinical efficacy in pediatric patients, there are very few studies specifically designed to evaluate asthma symptoms. Nevertheless, the results of rhinoconjunctivitis studies in children, which also assessed asthma, were pooled together in a meta analysis. Despite the large heterogeneity of the trials considered, the analysis showed that SLIT was significantly more effective than placebo in reducing symptoms and asthma medications (2). Well designed and adequately powered trials in children are urgently needed to assess the magnitude of the effect of SLIT in pediatric asthma.
In respect to the prevention of asthma in children with rhinitis, a randomized open prospective study in children receiving SLIT or drugs only was published in 2004 (3). This trial demonstrated that SLIT can reduce significantly the onset of asthma over a 3-year period of observation. Another large prospective randomized open trial (4), involving more than 200 children treated with SLIT or drugs alone for 3 years, demonstrated that SLIT reduced significantly the onset of persistent asthma and the onset of new skin sensitizations. Finally, a long-term follow-up of children with mite allergy (5), showed that SLIT reduced the onset of asthma, and that this effect was maintained for 5 years after discontinuation.
It is clear that more information is needed concerning the preventive effect of SLIT, although the available data are consistent with a preventive capacity of the treatment. It is anticipated that more detailed data on this aspect of SLIT will come from the follow-up phases of the ongoing large clinical trials.
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- Penagos M, Passalacqua G, Compalati E, Baena-Cagnani CE, Orozco S, Pedroza A, Canonica GW. Metaanalysis of the efficacy of sublingual immunotherapy in the treatment of allergic asthma in pediatric patients, 3 to 18 years of age. Chest. 2008 Mar;133: 599-609.
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- Marogna M, Tomassetti D, Bernasconi A, Colombo F, Massolo A, Businco AD, Canonica GW, Passalacqua G, Tripodi S. Preventive effects of sublingual immunotherapy in childhood: an open randomized controlled study. Ann Allergy Asthma Immunol. 2008 Aug;101(2):206-11.
- Di Rienzo V, Marcucci F, Puccinelli P et al. Long-lasting effect of sublingual immunotherapy in children with asthma due to house dust mite: a ten year prospective study. Clin Exp Allergy 2003; 33: 206-211.