Differential Ole e 1 Release from Olea Airborne Pollen in the Southwest Iberian Peninsula. Results from the HIALINE Study

Background: Ole e 1 is the major allergen of olive pollen (Olea europaea L.), the second largest cause of pollinosis in some areas from the Mediterranean Region. Although it has been assumed that airborne pollen is a representative parameter for allergen exposure, variability of allergen content and/or release from pollen has been demonstrated for other taxa. The aim of this study was to: i) estimate the correlation between daily airborne olive pollen and Ole e 1 in ambient air; ii) evaluate the annual and geographical variation of pollen and allergenic loads in southwest Iberian Peninsula; iii) evaluate the contribution of meteorological parameters to ambient Ole e 1 loads variations. Methods: Airborne Ole e 1 and olive pollen were assessed simultaneously in Cordoba, Spain and Evora, Portugal. Aeroallergens were collected in 2009-2011 using prewashed polyurethane foam as impacting substrate (Rupprecht & Patashnick ChemVol®2400 high-volume cascade impactor, Albany, NY, USA). Flow was adjusted to 800 L/min with a rotameter controlled high-volume pump (Digitel DHM-60, Ludesch, Austria). After extraction, Ole e 1 was quantified by ELISA. Airborne Olea pollen was monitored with a Burkard Hirst type Seven-Day Recording Volumetric SporeTrap®. Both samplers were placed side-by-side with the air input at the same level. Results: The aeroallergen and airborne pollen profiles overlapped during pollen seasons, however, deviations between pollen counts and allergen load were found. Annual pollen index of Olea was 3-4 folds higher in Spain (29,956, 26,274 and 42,223 in Spain versus 12,524, 7,144 and 10,499 in Portugal). A 4-9 fold difference in aeroallergen load was observed (14,375, 18,913 and 20,989 in Portugal and 108,720, 80,972 and 171,248 in Spain). Annual Ole e 1/pollen was 3.1-4.0 in Spain, 0.8-2.6 in Portugal and was positively correlated with precipitation prior to pollen season. Conclusions: These results have shown that Ole e 1 is mostly associated with olive pollen grains but aeroallergen load was not always directly proportional to airborne pollen counts. This suggests that Ole e 1 quantification is a better marker for olive allergen exposure. In conclusion, aeroallergen monitoring may contribute to a better understanding of the Ole e 1 exposure from airborne pollen. Acknowledgments: This study is integrated in the European project HIALINE (Executive Agency for Health and Consumers, grant agreement No 2008 11 07). 1st&2nd author equally contributed to the work