広島県におけるスギ・ヒノキ花粉の飛散状況と患者の抗原感作の経年的変化

抄録

Objectives: In Hiroshima Prefecture, the forest area of Japanese cypress outnumbers that of Japanese cedar by about twofold. In contrast to the case of cedar pollen, the amount of cypress pollen dispersion has been shown to increase over the years. We, therefore, investigated whether the changes in pollen dispersion amount and period had any effects on the degree of antigen sensitization against cedar and cypress pollens in allergic rhinitis patients.

Methods: We retrospectively surveyed the data of 8,558 patients who had allergy blood tests at Hiroshima University Hospital from 2001 to 2018. Antigen-specific IgE levels for cedar and cypress were determined by ImmunoCAP^TM Specific IgE systems. The pollen dispersion was annually monitored by a gravitational pollen sampler from 1996 to 2018. The cypress and cedar pollen counts were determined by staining with Calberla solution.

Results: An increase in both the amounts and dispersion periods of Japanese cypress pollen, as compared to that of cedar pollen, tended to be observed in Hiroshima Prefecture. The proportion of patients with positive ImmunoCAP scores increased for both cedar and cypress. However, the rate of increase was up to 25% for cypress as compared to 5% for cedar. Analysis by age group indicated that the rate of increase in cypress sensitization was the most significant in the younger population of patients aged less than 40 years old.

Conclusions: In Hiroshima Prefecture, the degree of antigen sensitization to Japanese cypress has risen due to an increase in both the number and period of pollen dispersion. Furthermore, the CAP score for cedar still remained positive in these sensitized patients. We consider that they are likely to suffer from continuous exposure to antigens in amounts in sufficient to maintain cedar sensitization.