Preliminary study of a challenge test to the patients with Japanese cedar pollinosis using an environmental exposure...

Although clinical studies on pollinosis have been performed employing placebo-controlled double-blind comparative and field techniques, accurate evaluation is difficult because the scattering pollen count and climatic conditions vary between years and regions, leading to a bias in the results. Thus, we prepared a pollen challenge test unit (allergen challenge chamber: ACC) which facilitates quantitative pollen challenge at any time, and, so, the acquisition of objective data.

The control of constant conditions and maintenance of specified pollen concentrations in ACC were investigated. In addition, the pollen distribution in ACC was measured while maintaining the level at 10,000 counts/m(3). The pollen levels were measured employing the aspiration and Durham methods, and the measured values were compared. Furthermore, whether symptoms are adequately induced in the chamber during the non-cedar pollen-scattering season was investigated in 14 volunteers with cedar pollinosis.

When the pollen level in ACC was set at 6000 counts/m(3) or higher, the rate of variation was +/-15%, within the adjustable range, and that of the pollen distribution in the chamber was within +/-20%. When the volunteers with cedar pollinosis were exposed to cedar pollen in ACC, pollinosis symptoms were induced, and challenge for 2 consecutive days significantly induced symptoms.

The temporal and spatial variations of the pollen level in ACC were small, facilitating stable pollen challenge, and pollinosis symptoms were induced in the volunteers with cedar pollinosis. The challenge chamber may be useful to judge the effects of therapy against pollinosis.