Isolation and characterization of an olive allergen‐like protein from lilac pollen

An olive allergen‐like protein has been isolated from lilac ( Syringa vulgaris ) pollen extract. The protein can be considered as an allergen since is recognized by IgE from olive hypersensitive human sera, and has been called Syr v I (IUIS nomenclature). This protein consists of a glycosylated polypeptide of 20 kDa, which has an amino acid composition, spectroscopic properties, and an N‐terminal sequence similar to the major allergen from olive pollen, Ole e I. The lilac allergen is recognized by rabbit polyclonal antisera raised against olive allergen as well as by an Ole e I‐specific monoclonal antibody. Using a polymerase chain reaction strategy, based on the similarities observed between these olive and lilac proteins, three cDNA clones encoding Syr v I have been isolated and sequenced. These clones code for a polymorphic protein of 145 residues with a derived molecular mass of about 16400Da, which contains a potential N ‐glycosylation site. Comparison of the deduced amino acid sequences of these Syr v I isoforms to each other revealed identities of 90–97%. Moreover, these sequences showed a high degree of similarity (85.5–89.6% identity) with Ole e I. The structural and immunological characterization of Syr v I justify the cross‐reactions observed between olive and lilac pollen extracts. The molecular cloning of Syr v I is relevant for the epitope mapping in Oleacease allergens, and may contribute to an improvement in the design of reagents for diagnosis and therapy of IgE‐dependent allergic reactions.