Immunological parameters in prophylactic sublingual immunotherapy in asymptomatic subjects sensitized to Japanese cedar pollen

Background: This study aims to examine the immunological parameters, focusing IL-10 productivity, in prophylactic sublingual immunotherapy (SLIT) in asymptomatic subjects sensitized to Japanese cedar pollen (JCP). Methods: This study was conducted as part of a randomized, double-blind, placebo-controlled, multiple center trial, and was performed for two consecutive pollen seasons in 2012 and 2013. The present results were based only on our institution. We recruited 29 participants with specific IgE against JCP of at class 2 and higher levels without history of the pollinosis symptoms at the time of JCP scattering. The SLIT group received standardized JCP extract for five months over the pollen season. We observed and judged development of the symptoms in the pollen season. The percentage of IL-10 producing CD4(+) T (Tr1) cells, B cells and monocytes were analyzed by flow cytometry. JCP specific IgE and total IgE were also measured. Results: The ratio of development of cedar pollinosis was significantly lower in the SLIT group compared to the placebo group in 2013. In 2012, the percentage of circulating Tr1 cells and IL-10 producing monocytes significantly increased in the SLIT group. In 2013, the percentage of circulating Tr1 cells and IL-10 producing B cells increased significantly in the SLIT group. The percentage of circulating IL-10 producing monocytes significantly decreased in the placebo group. Conclusions: Prophylactic SLIT is effective for prevention of the development of pollinosis. Induction of IL-10 producing T cells, B cells and monocytes is an important mechanism of SLIT for prevention of pollinosis in asymptomatic but sensitized subjects. Copyright (C) 2014, Japanese Society of Allergology. Production and hosting by Elsevier B.V. All rights reserved.