Background: In aerobiological studies, the Parietaria pollen type usually includes all Parietaria and Urtica species found in the area. Given that Urtica is a nonallergenic plant, the pollen counts report incomplete information on the presence of allergens in the atmosphere. Discordance between the pollen concentrations of Urticaceae and allergic symptoms has been observed in patients with pollinosis.
Objective: To compare the Urticaceae pollen counts with the Par j 1 and Par j 2 aeroallergen concentrations from 2 different Spanish geographic areas to determine the allergenic load in the atmosphere.
Methods: Hirst-type volumetric traps and Burkard Cyclone samplers were used for pollen counts and aeroallergen capture, respectively. The quantification of Par j 1 and Par j 2 allergens was performed using specific 2-site antibody enzyme-linked immunosorbent assay. Transmission electron microscopy and immunocytochemical techniques were applied to localize these allergens in the orbicules.
Results: Differences between areas and years were obtained in both pollen and aeroallergen concentrations. Despite the lower pollen counts recorded in Cartagena, higher aeroallergen concentrations were registered compared with Ourense. A lower correlation was achieved between Urticaceae pollen concentrations and aeroallergen levels, with a maximum positive significant correlation (adjusted R2 = 0.466, P < .001). Intense labeling of Par j 1 and Par j 2 proteins was observed in the orbicules, the tapetal membrane, and the tapetal tissue remnants.
Conclusion: This method may be valuable for epidemiologic research to establish correlations between concentrations of Parietaria aeroallergens and clinical symptoms. Therefore, the measurement of aeroallergens should be incorporated into the aerobiological studies with clinical applications.