Preliminary study on Japanese cedar pollinosis in an artificial exposure chamber (OHIO Chamber)

A pollen exposure chamber (OHIO Chamber) was built in central Tokyo, Japan, in order to study seasonal allergic rhinitis (SAR). Since satisfactory outcomes were obtained from the controlled pollen exposure at the chamber, we conducted preliminary studies in volunteers with SAR.

Ten volunteers with SAR sensitive to Japanese cedar (JC) pollen were enrolled in this study. In order to investigate the intranasal and intraocular pollen number, volunteers were initially exposed to a low concentration of JC (2500 grains/m3) for at most 1 hour in this chamber. Before and after the exposure, nasal cavities and eyes were washed with 100ml and 25 ml of saline, respectively. Nasal and eye washing solutions were collected and the number of JC pollen was counted. After 3 hours the volunteers were subsequently exposed to a moderate concentration of JC (4500 grains/m3) for 2 hours. Subjective nasal and ocular symptoms were recorded and the amount of nasal secretion was measured during the allergen exposure periods.

During the initial exposure, all volunteers except one stayed in the chamber for 1 hour without any nasal or ocular symptoms. The number of pollen in the nose and eyes was 249.2 +/- 120.9 and 13.6 +/- 13.6 grains, respectively. During the subsequent 2-hour exposure to JC pollen, nasal and ocular symptoms developed gradually in a time dependent manner in all the volunteers except one.

This is the first clinical study using Japanese cedar pollen under well-controlled conditions in the OHIO chamber in which the induction of allergic symptoms was observed. The OHIO chamber will be useful for studying allergic rhinitis in Japan.