Allergic sensitization to perennial allergens in adults and children sensitized to Japanese cedar or Japanese cypress pollen in Japan.

In Japan, seasonal allergic rhinitis in the spring due to exposure to Japanese cedar or Japanese cypress pollen is common. However, the allergic profile for perennial allergens in spring pollinosis remains unclear. Therefore, in this study, we investigated the allergic profiles of 652 patients with rhinitis. Total serum IgE, serum-specific IgE, and blood eosinophil counts were measured. Allergic sensitization, determined by the serum allergen-specific IgE level, did not always correspond with the patient's symptoms. Only 27% of patients with allergic symptoms in response to spring pollens were sensitized to these allergens alone; 31% of patients were also sensitized to perennial allergens, even without symptoms due to perennial allergens. Total serum IgE and eosinophil cell counts were significantly elevated in patients sensitized to perennial allergens and spring pollens, as compared to patients sensitized only to spring pollens. Most children sensitized to spring pollen (84%) were sensitized to perennial allergens, at a higher rate than adults (49%). Patients sensitized to spring pollens are likely to be latently sensitized to perennial allergens. This is especially true for children and should be monitored closely. Improvement in seasonal allergic conditions, including latent perennial allergy, is important to prevent symptoms that could advance to asthma.