A randomized controlled trial for the prevention of Japanese cedar pollinosis by sublingual immune therapy for the subjects with positive sensibilization having not symptoms

INTERVENTION: From December 2011 to Apirl 2012, 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 2012 to April 2013. From December 2011 to April 2012, 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 2012 to April 2013. CONDITION: Japanese cedar pollinosis PRIMARY OUTCOME: Affirmation of symotoms by cedar pollen antigen provocation test after cedar pollen scattering SECONDARY OUTCOME: 1.Change of parameters in blood.; 2.Safty. INCLUSION CRITERIA: 1)There is not medical history of cedar pollinosis 2)Positive specific IgE to cry j1/2 antigen(CAP‐RAST>=class2)