Background: The tree of heaven has spread from a prized ornamental plant to a highly invasive species in some regions worldwide. This tree was introduced in arid and semiarid regions of Iran as an ornamental species over the last two decades. Despite the increasing reports of Ailanthus spp. pollinosis, there have been very few molecular studies on this topic. The aim of this study was to identify potential allergenic proteins in A. altissimapollen using an animal model.
Methods: A. altissima pollens were collected from urban green spaces of Tehran, Iran, during the pollination period from Mid-April to Mid-May 2014.The pollen proteins were extracted in phosphate-buffered saline (PBS). The protein content of A. altissima pollen (AP) extract was studied using the Bradford protein assay followed by a 10% SDS-PAGE. Thirty male BALB/c mice were randomly divided into two groups of AP extract sensitized and sham that received PBS. The AP extract was injected intraperitoneally at regular intervals. One week after the last injection, intradermal skin tests (ID) were performed on the abdomen skin of each animal. Specific IgE-binding proteins of AP extract were identified by immunoblotting using pooled sera of sensitized mice.
Results: The total protein concentration of AP extract was 4.47 µg per µl. The AP extract SDS-PAGE pattern revealed 17 protein bands ranging from 10 kD to 100 kD. The mean wheal diameter induced by ID was significantly higher in the AP extract sensitized group compared to the sham group (P=0.00). Immunoblotting using pooled sera of AP extract sensitized mice revealed a major IgE-binding component of approximately 42 KD and several minor IgE-binding proteins ranging from 12 to 37 kD.
Conclusions: In the present study, several AP extract IgE-binding proteins have been identified as a potential cause of immediate hypersensitivity reactions in sensitized subjects. These findings open up avenues for identification of AP extract allergenic proteins and its allergen-based diagnosis in patients suffering from allergic symptoms during the pollination period of this species.