Abstract
In the water-soluble protein fraction of birch pollen 10–15 antigens can be demonstrated by immunodiffusion techniques employing immune serum from experimental animals. Only one or two of these antigens are also highly allergenic in humans, i.e., responsible for the spontaneous sensitization which eventually leads to respiratory allergic symptoms. The highly allergenic antigens are physiochemically more stable, have a lower molecular weight (around 20 000) and are more rapidly released from the pollen grains than the other antigens. By immunofluorescence and micro-immunodiffusion methods, release of the allergens has been found mainly to occur through the pollen apertures. These and other findings suggest that the allergens are easily mobilized to the pollen surface from underlying primary locations. Transmucosally immunized rabbits produced skin sensitizing “reaginic” antibodies preferentially against the allergenic antigens, while the antigens with low or no allergenic activity were more immunogenic than the highly allergenic ones when administered parenterally.