Sublingual immunotherapy for allergic rhinoconjunctivitis - The seeming and the real

Background: Subcutaneous specific immunotherapy ( SIT) has been shown to be a causal treatment with long-term efficacy for allergic rhinoconjunctivitis and asthma, and a preventive measure against the development of asthma and new sensitizations. As it is associated with several inconveniences and serious side effects, sublingual immunotherapy ( SLIT) has been developed to evade these problems. Methods: The present review of previously published studies on allergic rhinoconjunctivitis aimed to determine the efficacy of SLIT in comparison with subcutaneous treatment and to summarize long-term results of immunotherapy and its effects on the prevention and treatment of asthma and the prevention of new sensitizations. Results: The effect of SLIT on allergic rhinoconjunctivitis is low to moderate, depends on the allergen used and is more pronounced in adults than in children, in whom a consistent effect has not been demonstrated. Direct comparison with SIT shows conflicting and inconsistent results. Detailed studies on the prevention of asthma and new sensitizations are not available. Consistent effects of asthma treatment on both symptom and medication scores and lung function have not been reported. A quantitative evaluation is not possible due to indistinct inclusion criteria and different outcome criteria. In summary, currently SLIT plays no significant role in the treatment of asthma, apart from children mono-sensitized to house dust mites in whom it may have low-moderate effects. Only one study deals with the long-term efficacy of SLIT, which demonstrated a persistent positive effect on asthma, whereas data on rhinoconjunctivitis are completely lacking. Conclusions: Primary and secondary targets of specific immunotherapy have not been answered satisfactorily for the sublingual route. To date, SLIT cannot be recommended as an adequate alternative to the subcutaneous form. Questions regarding the cumulative dose, duration of therapy and immunological mechanisms have also not been answered. The indication should thus be limited to adult patients with pollen-induced rhinoconjunctivitis being unable to perform SIT, e. g. due to significant side effects. Copyright (C) 2005 S. Karger AG, Basel.