CONCENTRATIONS OF THE MAJOR BIRCH TREE ALLERGEN BET-V-1 IN POLLEN ANDRESPIRABLE FINE PARTICLES IN THE ATMOSPHERE

Background: Birch tree pollen allergens are an important cause of earl y spring hay fever and allergic asthma. Pollen counts provide a guide for individuals with birch pollen allergy. However, birch pollen, beca use of its size, has a low probability of entering the lower airways t o trigger asthma, Yet birch pollen allergens are known to be associate d with respirable particles present in the atmosphere. Objective: We s ought to determine the concentration of major allergen Bet v 1 in birc h pollen and respirable particles in the atmosphere during the birch p ollen season. Methods: We used a two-site monoclonal antibody-based as say (ELISA) to quantitate Bet v 1 in pollen extracts and high-volume a ir sampler filters collecting particles larger and smaller than 7.2 mu m. Results: Bet v 1 (0.006 ng) is detectable per birch pollen grain, of which 0.004 ng is present in aqueous extracts (13.9% of soluble pro teins), Atmospheric Bet v 1 concentrations are correlated with birch p ollen counts, Heavy rainfall tended to wash out pollen and particles, indicated by a mean daily Bet v 1 concentration of 0.12 ng/m(3) (20 po llen equivalents), but light rainfall produced a dramatic increase in allergen-loaded respirable particles with Bet vl concentrations of 1.2 ng/m(3) (200 pollen equivalents). Conclusion: These results highlight the different environmental risk factors for hay fever and allergic a sthma in patients sensitized to Bet v 1. Light rainfall causes an incr ease in respirable particles; hence, this is an important risk factor for asthma.