The future of sublingual immunotherapy

Abstract

Sublingual immunotherapy (SLIT) is currently the most prescribed form of allergen immunotherapy in many European countries. Its use has been accepted in the international consensus publications, and recently also the scepticism of USA scientists is attenuated. Still, this treatment may be improved, and the possible developments consist of modification of the materials, use of adjuvants and use of recombinant allergens. Moreover, new applications of SLIT, such as food allergy, seem promising. Concerning materials, the future form of SLIT is likely to be represented by tablets, which were already tested for efficacy and safety with grass pollen extracts, and are likely to increase the convenience for the patient by the use of no-updosing schedule. Adjuvants fitting with the characteristics of SLIT seem to be CpG oligodeoxynucleotides (CpG), able to interact with the Toll-like receptor 9 (TLR9) whose activation induces a Th1-like pattern of cytokine release, combination of 1,25-dihydroxyvitamin D3 plus dexamethasone (VitD3-Dex), and Lactobacillus plantarum. The approach with recombinant allergens, named component-resolved diagnosis, offers the possibility to tailor immunotherapy, which was found to be effective in two randomized trials of subcutaneous SIT (16-17), while studies with SLIT are not yet available. Regarding food allergy, an important controlled study demonstrated that SLIT with hazelnut is able to increase patients tolerance over possible reactions from inadvertent assumption of the culprit food, and warrants for further trials with other foods.