Persistent nasal symptoms and mediator release after continuous pollen exposure in an environmental challenge chamber

Immediate- and late-phase reactions are associated with nasal symptoms of patients with allergic rhinitis.

To examine the symptoms and mediators released after continuous allergen exposure in an environmental challenge chamber (ECC).

Fifteen patients with Japanese cedar pollinosis were enrolled in this study and continuously exposed to cedar pollen at a concentration of 8,000 grains/m(3) for 3 hours in an ECC. Nasal function tests were performed, and nasal secretions were collected before pollen exposure (0 hour), immediately after exiting the ECC (3 hours), and 6 hours after exiting the ECC (9 hours). Symptom scores were recorded every 30 minutes in the ECC and every 3 hours after exiting the ECC. The frequency of sneezing and nose blowing also was monitored.

The severity of symptoms in the ECC peaked approximately 2 hours after the beginning of pollen exposure and continued more than 6 hours after leaving the ECC. Concentrations of histamine, tryptase, interleukins 5, 3, 33, and 31, and substance P increased over time, whereas that of nasal fractional exhaled nitric oxide decreased.

Various mediators are released during continuous allergen exposure, which subsequently induce persistent nasal symptoms. Effective treatment is required to control the intense inflammation observed after allergen exposure.