Dynamics of airborne pollen particles from inhalation to allergic reaction in the nose

BACKGROUND: Pollinosis is common worldwide, and has been frequently studied. However, the intranasal dynamics of pollen grains have not yet been documented. The purpose of this study is to elucidate for the first time the dynamics of Japanese cedar pollen (JCP) in the human nose at consecutive steps from inhalation to allergic reaction together with release of Cry j 1 (a major allergenic component of JCP) in the nose. METHODS: A personal sampler collected airborne pollens at head height outdoor on the street, while intranasal pollens after natural or experimental inhalation were collected by irrigation with 200ml saline. Cry j 1 in the supernatant after in vitro incubation with phosphate buffered saline or lavage was determined by enzyme-linked immunoassay. RESULTS: Head-height pollen was 183.0 +/- 43.1/300L/h, with 99% of the inhaled pollens deposited on the nasal surface. Eighty eight% of the inhaled pollen was transported to the out-side of the nose by ciliary function within 3 hours. During this process, considerable amounts of Cry j 1 were released in the nose reaching its plateau within 30 min. When the number of pollen deposited exceeded more than approximately 65 particles, symptoms may occur, leading presumably up to a 74% reduction of the intra-nasal pollen. CONCLUSION: The majority of inhaled airborne pollens was deposited on the nasal mucosal surface and moved out from the nose by mucociliary transportation. During this process, when allergenic substances are released up to a critical concentration, allergic reactions occur leading to expelling of pollen from the nose followed by subsiding of the symptoms.