Why are nasal and bronchial symptoms mostly perennial in patients with monosensitization to Olea europaea pollen allergens?

In the last few years interest in the clinical aspects of Olea europaea (O.e.) pollen allergy has increased. For many years we have observed in our geographical area a perennial pattern of clinical symptoms in subjects with monosensitization to O.e. allergens without any worsening during the olive pollen season. We tried to demonstrate the clinical relevance of O.e. sensitization in our patients and, moreover, to determine why this pattern is elicited. We selected a group of 26 patients with rhinitis and/or bronchial asthma and an immediate positive skin reaction only to O.e. pollen extract. Using commercially available extracts and reagents, the following diagnostic procedures were performed: Skin prick tests (SPT), specific O.e. IgE assays, nonspecific bronchial provocation tests (NsBPT) and specific nasal provocation tests (sNPT), respectively, in patients with bronchial asthma and rhinitis. Pollen counts and a statistical analysis using Spearman's correlation test were also carried out. 21 of 26 O.e. monosensitive patients showed perennial type of clinical symptoms without any particular worsening during olive pollination season. We found a high degree of statistical significance between the results of SPT/sNPT and serum specific IgE determination. Many patients exhibited a late response after sNPT. No definitive data were derived from our findings, even though the occurrence of many late reactions after sNPT could in part explain the perennial type of nasal symptoms. We would like to emphasize the necessity of better purification and standardization of diagnostic materials and, moreover, suggest further studies with a greater number of O.e. monosensitive patients living in different geographical areas.