Atmospheric exposure to the major Artemisia pollen allergen (Art v 1): Seasonality, impact of weather, and clinical implications

Abstract

Artemisia pollen grains are important aeroallergens worldwide. The amount of allergenic proteins produced by pollen, or pollen allergenicity, is regulated by both genes and the environment. As a result, even closely related plant taxa may release pollen with distinctly different allergen contents. Here, we determined the variability in atmospheric exposure to the major Artemisia pollen allergen, Art v 1, during the pollination seasons of two common species, i.e., A. vulgaris (early flowering species) and A. campestris (late flowering species), in Poznań, Poland (2013-2015). Artemisia pollen grains were collected using Hirst-type volumetric trap, while Art v 1 was collected by a two-stage cascade impactor (PM₁₀ and PM_>10 air fractions) and quantified by immunoenzymatic analysis. The results showed that daily Art v 1 levels correlated significantly with mean daily concentrations of Artemisia pollen (from r = 0.426 to r = 0.949, depending on air fraction and peak of the season). Significant differences were observed between 1) the median pollen allergenicity in different seasons (from 2.5 to 4.7 pg Art v 1/pollen) and 2) the median pollen allergenicity in different peak periods of the season (from 1.8 to 6.7 pg Art v 1/pollen). During the late peak (flowering of A. campestris), the median pollen allergenicity was significantly higher (on average by 63%, p < 0.05) than that during A. vulgaris flowering. The highest mean seasonal pollen allergenicity was observed during the wettest season, while the lowest was observed during the driest season (from July-August). In summary, our study showed distinct differences in Artemisia pollen allergenicity, that were not only related to daily and seasonal variability, which may exceed 800% and 80%, respectively but also noticeable when two common Artemisia species were compared. Therefore, we argue that variability in pollen allergenicity (both seasonal and species-specific) should be considered in future studies assessing pollen exposure.

Keywords: Air fractions; Allergenicity; Mugwort; Pollen allergy; Subpollen particles.