Comparison of concentrations of Cry j 1 and Cry j 2 in diploid and triploid Japanese cedar (Cryptomeria japonica) pollen extracts

Japanese cedar ( Cryptomeria japonica ) pollinosis has been a serious allergic disease in Japan. There are two kinds of Japanese cedar trees; the popular one is diploid, the less popular is triploid. These trees are not very different morphologically. However, the relative allergenicity of their pollens is unknown, although both major allergens, Cry j 1 and Cry j 2, have been purified and cloned from the diploid line. Triploid trees are sterile and the allergenicity of their pollen may differ. Using Japanese‐cedar‐allergic patient sera, we compared the concentration of these two major allergens in both kinds of pollen. Pollen collected from different years and regions was also studied. The results indicate that triploid tree pollen extract has lower concentrations of both major allergens; therefore, the pollen may be less allergenic.