Pru p 9, a new allergen eliciting respiratory symptoms in subjects sensitized to peach tree pollen.

Peach tree (PT) pollen sensitization is highly prevalent in subjects living in areas where this tree is widely cultivated. None of the allergens responsible for these sensitizations have been identified so far. Our aim was to identify the most relevant PT pollen allergens and analyze their capacity for inducing respiratory symptoms. We studied sixty-two individuals sensitized to PT pollen who developed symptoms after its exposure. The IgE binding profile on peach pollen extract by means of immunoblotting using sera from these subjects was analyzed. Protein extract was fractionated by anion-exchange chromatography and HPLC, fractions run in SDS-PAGE and proteins were identified from IgE-binding bands by mass spectrometry. Several allergenic proteins in the PT pollen extract were recognized by patients' IgE: a glucan endo-1,3-beta-glucosidase-like, a polygalacturonase, an UTP-glucose-1-phosphate uridylyltransferase and a PR-1a protein. This PR-1a protein is a novel allergen frequently recognized with a molecular mass of 18 kDa, named as Pru p 9 following the WHO-IUIS nomenclature. Skin Prick Test (SPT) performed with this allergen was positive in 41% of the PT pollen-sensitized clinical cases. Most of them had rhinitis or rhinoconjunctivitis, but a significant percentage experienced asthma with seasonal symptoms during the period of PT flowering. Nasal Provocation test (NPT) with Pru p 9 was positive in all cases with positive SPT to this new allergen eliciting nasal symptoms similar to those challenged with PT pollen. We demonstrate that PT pollen can induce sensitization and allergy in an exposed population, being Pru p 9 a relevant allergen responsible of respiratory symptoms. Considering the extensive peach worldwide production with a large number of people involved, our results add a great value for the diagnosis and management of subjects allergic to this pollen.

Peach Tree Pollen and Prunus persica 9 Sensitisation and Allergy in Children and Adolescents.

BACKGROUND: Although plant and fruit pollens are entomophilous and relevant in exposed workers, we have shown a high frequency of sensitisation and symptoms induction of peach tree pollen (PTP) and Prunus persica 9 (Pru p 9) in adults from areas of peach cultivars. METHODS: We studied the sensitisation and clinical relevance of PTP and Pru p 9 in a large group of children and adolescents aged 3-19 years. A detailed questionnaire plus skin prick testing to prevalent allergens, PTP, and Pru p 9 were carried out. The clinical relevance was established by nasal provocation test (NPT) and symptom score index. RESULTS: We evaluated 685 children (mean age 8.75 ± 3.3 years, median 9 years), 52% of them female. Sensitisation to PTP occurred in 20% of the cases following olive tree (33%) and Phleum pratense (26%). In a randomly selected subgroup of subjects sensitised to PTP, 30% were skin prick test-positive to Pru p 9. Most cases had rhinitis or rhinoconjunctivitis. NPT showed the relevance of PTP and Pru p 9 in the induction of symptoms. CONCLUSION: PTP and Pru p 9 are relevant in the induction of sensitisation and respiratory symptoms in children and adolescents. This allergen should be evaluated in children living in regions of peach tree cultivars.

Identification of the ligand of Pru p 3, a peach LTP.

KEY MESSAGE: Pru p 3, a peach LTP, is located in pollinated flower styles and secreting downy hairs, transporting a derivative of camptothecin bound to phytosphingosine. Pru p 3 may inhibit a second pollination and may keep away herbivores until seed maturation. The allergen Pru p 3, a peach lipid transfer protein, has been well studied. However, its physiological function remains to be elucidated. Our results showed that Pru p 3 usually carries a lipid ligand that play an essential role in its function in plants. Using ESI-qToF, we observed that the ligand was a derivative of camptothecin binding to phytosphingosine, wich that is inserted into the hydrophobic tunnel of the protein. In addition, the described ligand displayed topoisomerase I activity inhibition and self-fluorescence, both recognized as camptothecin properties. During flower development, the highest expression of Pru p 3 was detected in the styles of pollinated flowers, in contrast to its non-expression in unpollinated pistils, where expression decreased after anthesis. During ripening, the expression of Pru p 3 were observed mainly in peel but not in pulp. In this sense, Pru p 3 protein was also localized in trichomes covering the fruit epidermis.