Rhinitis, sinusitis, and upper airway disease
Variation of the group 5 grass pollen allergen content of airborne pollen in relation to geographic location and time in season

https://doi.org/10.1016/j.jaci.2015.01.049Get rights and content

Background

Allergies to grass pollen are the number one cause of outdoor hay fever. The human immune system reacts with symptoms to allergen from pollen.

Objective

We investigated the natural variability in release of the major group 5 allergen from grass pollen across Europe.

Methods

Airborne pollen and allergens were simultaneously collected daily with a volumetric spore trap and a high-volume cascade impactor at 10 sites across Europe for 3 consecutive years. Group 5 allergen levels were determined with a Phl p 5–specific ELISA in 2 fractions of ambient air: particulate matter of greater than 10 μm in diameter and particulate matter greater than 2.5 μm and less than 10 μm in diameter. Mediator release by ambient air was determined in FcεRI-humanized basophils. The origin of pollen was modeled and condensed to pollen potency maps.

Results

On average, grass pollen released 2.3 pg of Phl p 5 per pollen. Allergen release per pollen (potency) varied substantially, ranging from less than 1 to 9 pg of Phl p 5 per pollen (5% to 95% percentile). The main variation was locally day to day. Average potency maps across Europe varied between years. Mediator release from basophilic granulocytes correlated better with allergen levels per cubic meter (r2 = 0.80, P < .001) than with pollen grains per cubic meter (r2 = 0.61, P < .001). In addition, pollen released different amounts of allergen in the non–pollen-bearing fraction of ambient air, depending on humidity.

Conclusion

Across Europe, the same amount of pollen released substantially different amounts of group 5 grass pollen allergen. This variation in allergen release is in addition to variations in pollen counts. Molecular aerobiology (ie, determining allergen in ambient air) might be a valuable addition to pollen counting.

Section snippets

Pollen in ambient air

Airborne pollen concentrations were collected at 10 sites in Europe (Table I and see Table E1 and Fig E1 in this article's Online Repository at www.jacionline.org) by using Hirst-type volumetric spore traps, according to the requirements of the European Aeroallergen Network.28 Quality of counts was controlled, as described previously.19

Allergen in ambient air

Air was simultaneously sampled at each site with ChemVol (Butraco, Son, The Netherlands) high-volume (800 L/min) cascade impactors equipped with dry polyurethane

Pollen in ambient air

Airborne grass pollen is ubiquitous in Europe, but large variations in pollen counts exist between countries. A map of the stations is presented in Fig E1. The Finnish station in Turku (seaside) showed the lowest pollen counts, whereas the Portuguese station in Evora (rural site) recorded the highest counts (Table I). It should be noted that the years studied for each station were within the normal range of the preceding years for all stations (season timing and total pollen counts were within

Discussion

Pollen is the major outdoor cause for allergic rhinitis, and more than 350 pollen traps over Europe monitor pollen flight daily.39 The immune system reacts with symptoms to allergens,40 which are carried and released by pollen. The natural variability across Europe of how much allergen is carried by grass pollen was unknown.

This study shows that, on average, grass pollen in Europe released about 2.0 to 2.5 pg of group 5 allergens, the major grass pollen allergen, per pollen grain. This average

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  • Cited by (0)

    This publication arises from HIALINE, a project that has received funding from the European Union in the framework of the Health Programme.

    Disclosure of potential conflict of interest: J. Buters has received or has grants pending from Foundation CK-CARE. S. Celenk's institution has received funding from the Scientific and Technological Research Council of Turkey (TUBITAK 109S032). B. Weber is employed by Allergopharma GmbH & Co. KG. The rest of the authors declare that they have no relevant conflicts of interest.

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