Purification and characterization of Pla a 1, a major allergen from Platanus acerifolia pollen

Background: Plane trees, as Platanus acerifolia, are an important source of airborne allergens in cities of the United States and Western Europe. Little is known about the relevant allergens of this pollen. The aim of this study was to identify relevant allergens from P. acerifolia pollen and purify and characterize a major allergen of 18 kDa. Methods: P. acerifolia pollen extract was fractionated using ion exchange, gel filtration, and reverse-phase chromatography. Analyzes were carried out by EAST, SDS-PAGE, isoelectric focusing, immunoblotting and amino-acid sequencing, Results: An 18-kDa protein from the P. acerifolia pollen extract, which we named Pla a 1, was purified. This nonglycosylated protein had an isoelectric point value higher than 9.3 and was recognized by up to 92% of monosensitized Platanus allergic patients and 83% of polyzensitized patients. Sequencing of its N-terminal yielded an amino acid sequence which showed no homology to the known proteins in the databases. Other relevant allergens detected in monosensitized patients were proteins of 43 and 52 kDa, with immunoglobulin (Ig)E-binding prevalences of 83 and 42%, respectively. Profilin was an important allergen in polyzensitized patients. Conclusions: The most relevant allergens from the P. acerifolia pollen have been determined. A major allergen, specific of this pollen, and named Pla a 1, has been purified and characterized.