Identification, isolation, and characterization of Ole e 7, a new allergen of olive tree pollen

Abstract

Background: Olive tree ( Olea europaea ) pollen is an important cause of pollinosis in countries of the Mediterranean area and California. Objective: The aim of this study was to identify and purify a new allergen of olive tree pollen. Methods: Detection of a pollen allergen was done with individual allergic sera by immunoblotting and ELISA tests. Two allergenic fractions were isolated from olive pollen extract by using gel filtration and reverse-phase HPLC. Molecular characterization was achieved by acid hydrolysis and amino acid analysis, as well as by mass spectrometry. Sequencing of the N-terminal end of the allergen was carried out by Edman degradation of the polypeptide chain. Allergenic characterization was performed with sera from subjects with olive allergy by means of ELISA and immunoblotting after SDS-PAGE. Results: The new allergen Ole e 7 exhibits a high degree of polymorphism. Its molecular mass is in the range of 9875 d to 10,297 d. Twenty-one amino acid residues from the N-terminal end of 2 isoforms of the allergen have been sequenced revealing no homology with proteins contained in database banks. Ole e 7 has an average frequency of about 47% in patients with olive allergy. The strategy of purification of Ole e 7 can be useful on the isolation of new allergens. Conclusions: A new olive pollen allergen of clinical significance has been purified and characterized, contributing to the study of the complete allergogram of the olive tree pollen. (J Allergy Clin Immunol 1999;104:797-802.)