Semiquantitative and qualitative analysis of pre-seasonal airborne birch pollen allergens in different particle sizes - Background information for allergen reports

Bet v 1, the major allergen of birch pollen, has been reported to be synthe tized in pollen grains shortly before anthesis. In order to obtain a better understanding of the causative agents of allergic symptoms which appear be fore the actual pollen season, the activity birch pollen antigen in outdoor air have been studied, using polyclonal antibodies against birch pollen, a nd monoclonal antibodies against Bet v 1. Using a size-selective bioaerosol sampler (SSBAS), birch pollen antigen concentrations were analysed separat ely in different particle size classes, down to the molecular size range. About a week before the anthesis of alder, antigens were already detected i n outdoor air samples. They were found mainly in the smallest particle size classes and might have had their origin in the developing leaves and flowe r structures of Betulaceae trees. Al the beginning of birch anthesis Bet v 1 activity in the air increased markedly. The smallest particles may have b een orbicules (2-4 mu m) and starch granules (0.5-2 mu m) from inside the p ollen and present among the other particles. Birch pollen antigens were fou nd throughout the whole study season. Peaks in activity preceding the start of alder pollination were most probably due to cross-reactivity between th e main allergens Aln g 1 of alder and Bet v 1. The results support the idea that all airborne allergens of Betulaceae pollen could for practical purpo ses be monitored by using monoclonal antibodies against Bet v 1.