Oriental plane trees are an important source of airborne allergens in cities of southwest Asia. In spite of extensive studies on Platanus acerifolia allergy, there are no reports on the molecular characterization of pollen allergens from Platanus orientalis trees. In this study, a newly recognized member of cyclophilin family with a molecular weight of 18 kDa was identified as being partly responsible for IgE reactivity of P. orientalis pollen extract. (C) 2008, The Society for Biotechnology, Japan. All rights reserved.