Study for the prevention of Japanese cedar pollinosis by sublingual immunotherapy with Japanese cedar pollen extract. - A randomized controlled trial for the subjects with positive sensibilization having not symptoms -

INTERVENTION: From December 2014 to Apirl 2015, patients of control 1 receive active treatment everyday. The induction/build‐up phase is 2 weeks,with an increasing daliy number of the extract drops at two consentrations. Same treatmet is conducted from December 2015 to April 2016 and from December 2016 to April 2017. From December 2014 to April 2015, patients of control 2 receive placebo everyday. The induction/build‐up phase is 2 weeks,with an increasing daliy number of the placebo drops as control 1. Same treatmet is conducted from December 2015 to April 2016 and from December 2016 to April 2017. CONDITION: Japanese cedar pollinosis PRIMARY OUTCOME: Ratio of onset of Japanese cedar pollinosis(1 and 2); 1.Increasing of nasal symptom score in the peak pollen season; 2.affirmation of symotoms by cedar pollen antigen provocation test after cedar pollen scattering SECONDARY OUTCOME: 1.Increasing of nasal symptom score in the peak pollen season.; 2.Affirmation of symotoms by cedar pollen antigen provocation test after cedar pollen scattering ; 3.Adherence of sublingual immunotherapy; 4.Safty INCLUSION CRITERIA: 1)There is not medical history of cedar pollinosis 2)Positive specific IgE to cry j1/2 antigen(ImmunoCAP>=class2) 3)No affirmation of symotoms by cedar pollen antigen provocation test before entering the examination.