Sublingual immunotherapy for allergic rhinitis: subjective versus objective tools to evaluate its success

Background: Biomarkers that enable objective evaluation of the clinical effects of immunotherapy for allergic rhinitis have yet to be identified. Methods: This study included 40 patients who were enrolled in a large randomized, double-blind, placebo-controlled, multi-center study examining the efficacy of sublingual immunotherapy (SLIT) using Japanese cedar (JC) pollen extract during two consecutive pollen seasons from 2010 to 2012. Based on changes in total nasal symptom medication score, patients in the SLIT and placebo groups were subdivided into two subgroups: good responders and poor responders.The levels of JC pollen-specific IL-10(+)Foxp3(+) cells and specific Th2 cytokine-producing cells were measured and the association with the efficacy of SLIT was analysed. Results: The total nasal symptom medication score was significantly lower in the SLIT group compared with the placebo group. The number of JC pollen-specific Th2 cytokine-producing cells increased during the pollen season in the placebo group and in poor responders in the SLIT group; however, the increases were inhibited in the good responders in the SLIT group. The number of JC pollen-specific IL-10(+)Foxp3(+) cells increased only in these good responders. Conclusions: Changes in levels of allergen-specific Th2 cytokine-producing cells and IL-10(+)Foxp3(+) cells could be objective biomarkers for SLIT.