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The major allergen Bet ver 1 of Betula pendula (= B. verrucosa) pollen grains has been localized by gold labelling with monoclonal antibodies. The allergen is located predominantly in the starch grains and to a slight extent in the exine and intine. The possibility that environmental factors might influence the liberation of allergenic compounds present in birch pollen grains is discussed.

Confocal laser scanning microscopy (CLSM) was used to localize the major allergen, Bet v I in birch pollen. Pollen grains of Belula pendula were collected from catkins that had begun to release their pollen, freeze dried, and stored at 4°C. The pollen material was cryosectioned and stained with indirect immunofluorescence using the monoclonal antibody Bv 10. The observed localization of Bet v I was dependent on the treatment of the grains. When they had been prefixed with gaseous formaldehyde followed by acetone Bet v I was found in the cytoplasm. When the prefixation was omitted, a minor portion of Bet v I also appeared in the exine in the aperture regions. The allergen was not observed in the intine or the Zwischenkorper. Our suggestion is that the normal route for excretion of Bet v I is via the apertures on contact between pollen and the stigmatic surface of the pistil.

The existence of small particles emitted from the dehiscing anther at the time of pollen shedding is shown. We examined pollen samples of five plants causing pollinosis in Japan: Cryptomeria japonica, Alnus japonica, Quercus serrata, Dactylis glomerata and Ambrosia elatior. The pollen samples of C. japonica collected by hydroponic culture had two kinds of particles. The size of these particles was 0.46 to 1.4 μm and 29 to 40 μm (pollen grains) in diameter. The number of the small particles was about 8-fold greater than that of intact pollen grains. Alnus japonica, Quercus serrata and Dactylis glomerata also discharge small particles other than pollen grains although the number is not so large as Cryptomeria japonica. We could not recognize any small particles in a pollen sample of Ambrosia elatior.

Airborne grass pollen in a grassland was measured using a Burkard air sampler and immunoblotting. The pollen antigens collected on the tape of the air sampler were transferred onto a nitrocellulose membrane, and visualized as purple spots by immunoenzymatic staining with anti-Lol p I antibody. These spots were quantified automatically using an image processing system. The airborne grass pollen antigens in the grassland where four species of grass were growing were prevalent mainly from evening to early morning during the first half of the pollen season, but in the daytime during the latter half of the season. The antigen dispersion time was confined to a few hours of the day. The flowering time of several grass species which were hydroponically cultured in the laboratory were also studied. Each species had a different flowering time. We believe that the time when an antigen is present during the day is related to the different flowering times of the various grass species growing in the grassland.