Retention of pollen grains in human lung

Quantification of airway deposition of intact and fragmented pollens

Although pollen is one of the most widespread agents that can cause allergy, its airway transport and deposition is far from being fully explored. The objective of this study was to characterize the airway deposition of pollens and to contribute to the debate related to the increasing number of asthma attacks registered after thunderstorms. For the quantification of the deposition of inhaled pollens in the airways computer simulations were performed. Our results demonstrated that smaller and fragmented pollens may penetrate into the thoracic airways and deposit there, supporting the theory that fragmented pollen particles are responsible for the increasing incidence of asthma attacks following thunderstorms. Pollen deposition results also suggest that children are the most exposed to the allergic effects of pollens. Finally, pollens between 0.5 and 20 μm deposit more efficiently in the lung of asthmatics than in the healthy lung, especially in the bronchial region.

Detection of Parietaria judaica airborne allergenic activity: comparison between immunochemical and morphological methods including clinical evaluation

Airborne pollen grains and small plant particles of respirable size are the main causes of rhinitis and asthma in pollinosis patients. Consequently, it could be useful to quantify atmospheric variations in these biological aerosols and their allergenic activity as a basis for establishing correlations with the clinical symptoms in these allergic subjects. Our study was conducted in Naples from May to August 1992 and from May to August 1993 and concentrated on Parietaria judaica (Par j) the most important hay fever-provoking plant in southern Italy. The aim of this study was to evaluate the day-to-day variation in counts of Par j. pollen, the day-to-day variation in allergenic activity specific for this plant, and to relate these two variables to symptom scores in patients with respiratory allergy to Par j. The airborne pollen grains were collected by a Hirst-like volumetric trap and examined through an optical microscope, while the allergenic activity of particles trapped on glass fibre filters in a high volume air-sampler was determined by immunochemical assay. The two devices were placed on the flat roof of the 'A. Cardarelli' Hospital. The results of this preliminary study suggest that both methods could have useful clinical relevance, since these two biological parameters were significantly correlated with the symptom scores of allergic patients. However, pollen count with morphological quantification of grains/m3 of air is a more simple technique.

Airborne birch pollen antigens in different particle sizes

Two particle samplers for ambient air, situated together: a static size-selective bio-aerosol sampler (SSBAS) and a Burkard pollen and spore trap were compared in sampling intact birch pollen grains through one flowering period of Betula (a total of 44 days). The SSBAS trapped pollen grains three times more efficiently than the Burkard trap, but the variations in pollen counts were significantly correlated. In contrast, birch pollen antigenic activity and the pollen count in the Burkard samples were not closely correlated. The antigenic concentration was occasionally high both before and after the pollination period. There was a high birch pollen antigenic activity in particle size classes where intact pollen grains were absent, even on days when the pollen count was very low. Correspondingly, on days with high birch pollen counts in the air, pollen antigenic activity was on several occasions low, indicating that pollen grains were empty of antigenic material. The small particle size classes are especially important to allergic patients because they are able to penetrate immediately into the alveoli and provoke asthmatic reactions. Therefore, aerobiological information systems based on pollen and spore counts should be supplemented with information concerning antigenic activities in the air.

Evidence of grass-pollen allergenic activity in the smaller micronic atmospheric aerosol fraction

In June 1988, during the grass-pollen season in Leiden, The Netherlands, outdoor airborne particulate matter was collected and separated into fractions according to aerodynamic sizes (greater than or equal to 10 microns, 4.9-10 microns, 2.7-4.9 microns, 1.3-2.7 microns, 0.6-1.3 microns, less than or equal to 0.6 microns), with a cascade impactor mounted on top of a high volume sampler. The different fractions were tested for the presence of grass-pollen allergenic activity using a RAST-inhibition assay: specific IgE-antibody-containing patient serum was applied on the particle-loaded impaction strips, and the serum was recovered by descending elution for further analysis in the RAST. Simultaneously, continuous measurements were made of the airborne grass-pollen concentration using a volumetric pollen trap. Sampling observations lasting 7-9 hr during a period with relatively high airborne grass-pollen concentrations showed reliably detectable amounts of grass-pollen allergen, not only in the first impaction stage where intact pollen were collected, but also in the lower stages collecting the smaller, paucimicronic and submicron atmospheric aerosol fraction. It is evident that this result has serious implications for the understanding of the bronchial symptoms frequently seen in hay fever patients on days with high pollen concentrations in the air.