Elsevier

Toxicology Letters

Volume 165, Issue 1, 1 August 2006, Pages 71-78
Toxicology Letters

Detection of allergens adsorbed to ambient air particles collected in four European cities

https://doi.org/10.1016/j.toxlet.2006.01.016Get rights and content

Abstract

Air pollution has been implicated as one of the factors responsible for the increased incidence of allergic diseases observed in recent years. High concentrations of air pollutants may promote airway sensitization by acting as adjuvants. Ambient particles as carriers of adsorbed allergens are, therefore, of special interest since they may act as mediators of inflammatory as well as allergic responses. Ambient air particles from four cities in Europe were collected, in three different seasons, to examine the variation of allergens and their possible binding to the pollution particles. The particle fraction, PM10, was collected on polycarbonate filters using a low-volume sampling regime. The presence of pollen allergens, latex and β-glucans was investigated using an immunogold labelling method directly on the collection filters. Scanning electron microscopy revealed mainly the classical carbon particles and aggregates determined to originate from vehicle exhaust. The immunogold labelling visualised in the backscatter electron imaging mode, showed that allergens from pollens, latex and also β-glucans were bound to and, hence, transported by the combustion particles in ambient air. Thus, combustion particles in ambient air are carriers of allergens and act as depots of allergens inhaled into the airways.

Introduction

Environmental factors such as allergens and air pollution have been proposed to promote the induction and elicitation of respiratory allergies. It has been demonstrated that pollen allergens from trees, grasses and weeds are released in the form of submicronic particles that may be loaded onto other particles (Grote et al., 2003, Taylor et al., 2004). Correspondingly, combustion particles from vehicles and industry and their aggregates in ambient air, have been shown to adsorb allergens (Knox et al., 1997, Namork et al., 2004, Ormstad et al., 1995). Furthermore, combustion particles have an adjuvant effect increasing the IgE production of susceptible individuals upon exposure to allergens (Diaz-Sanchez et al., 1999, Nygaard et al., 2005, Takafuji et al., 1989a). Thus, the interaction between air pollution particles and allergens may enhance allergic airway responses (D’Amato, 2002, Polosa, 2001).

The relation between particle exposure and adverse health effects shows geographical differences (Janson et al., 2001). Ambient particles may differ qualitatively at different locations, accounting for differences in relation to the induction of inflammatory responses and the elicitation of allergy (Polosa et al., 2002). A research project “Respiratory Allergy and Inflammation due to Ambient Particles—a European-wide Assessment” (RAIAP, 2004), was initiated to investigate if qualitative differences in particulate air pollution partly could explain differences in prevalence and severity of respiratory allergies throughout Europe (Nygaard et al., 2005). Ambient air particle fractions were collected in the cities of Amsterdam in The Netherlands, Lodz in Poland, Rome in Italy and Oslo in Norway, during the spring, winter and summer seasons in 2001–2002.

The specific object of the present study was to examine ambient air samples from cities in the western, central, northern and southern Europe, for representative pollen allergens carried by ambient particles. Since vehicle traffic is a predominant particle source in urban areas, and latex is a substance in car tires, the presence of latex allergens was also investigated. Beta-(1-3)-glucans, from the cell wall of plants and microbes, are also believed to play a role in bioaerosol-induced respiratory symptoms (Wan et al., 1999, Rylander and Lin, 2000). An immunogold labelling method was used to detect the allergens and β-glucans, and the labelling was visualised in the backscatter electron imaging mode of a scanning electron microscope (Namork, 1991).

Section snippets

Sampling of particulate matter

A high volume cascade impactor was used to collect particulate matter (PM) fractions, in spring, summer and winter in the cities of Amsterdam, Rome, Lodz and Oslo for physio-chemical characterization (Cassee et al., 2003). The duration of sampling and transportation of the impactor between the countries in the different seasons allowed only one sampling at each site per season. Low volume sampling employing a commercially available impactor unit for collection of PM10 (URG Corp. USA) was built

Results

The mass concentrations of ambient air particles were higher in winter for all four cities, compared to the other two seasons. Using the low volume collection method, the highest mass concentrations were measured in winter in Lodz (66 μg/m3) and Rome (61 μg/m3) compared to 34 μg/m3 and 13 μg/m3 in Oslo and Amsterdam, respectively. The mass concentrations were lowest in spring in Oslo (15 μg/m3) and Amsterdam (16.3 μg/m3) compared to Lodz (22.9 μg/m3) and Rome (33.8 μg/m3).

Scanning electron microscopy

Discussion

Car traffic dominates the four collection sites, and previous examination of the morphological and elemental composition by transmission electron microscopy and energy-dispersive X-ray microanalysis, showed that the majority (>90%) of the ambient particles consisted of combustion particles aggregated into typical grape-like clusters (Cassee et al., 2003). Similarly, the carbon aggregates observed on all present air filters, appeared to be combustion particles originating from vehicle exhaust,

Acknowledgements

We aknowledge John Boere who was responsible for the schedule and central organization of the RAIAP sampling campaign. We thank the scientists who donated the antibodies (see Section 2). We also thank Jan Zahlin and Astri Grestad for invaluable technical assistance. This work was supported by the RAIAP project (Respiratory Allergy and Inflammation due to Ambient Particles)—A European Commission Shared-Cost Research Project QLK-CT-2000-00792.

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