Mapping of IgE-binding regions on recombinant Cyn d 1, a major allergen from Bermuda Grass Pollen (BGP)

A cDNA library was constructed from Bermuda grass pollen (BGP) using a Lambda gt11 expression vector. The gene encoding the Cyn d 1 allergen was isolated by screening the library with a mouse monoclonal antibody raised against grass group 1 allergen. In order to characterize the IgE epitopes on Cyn d 1, seven overlapping fragments and three deletion mutants were cloned and over-expressed in E. coli. The recombinant fragments and deletion mutants were evaluated for their comparative IgE reactivity with sera of non atopic individuals and grass pollen allergic patients by ELISA and a dot-blot assay.Analysis of IgE binding regions by overlapping fragments and deletion mutants identified two major allergenic regions corresponding to amino acids 120–170 and 224–244. Deletion of either or both regions led to a significant reduction in IgE binding, emphasizing the importance of the C-terminal region on Cyn d 1 in epitope-IgE interaction.Anti-Cyn d 1 IgE antibodies from allergic human sera recognize two epitopes located at the C-terminal end of the molecule. These data will enable the design of improved diagnostic and therapeutic approaches for BGP hypersensitivity.It is estimated that up to 20% of the population in developed countries suffers from atopic diseases caused by airborne allergens derived from grass and tree pollen, house dust mites and animal dander, which has a significant impact on quality of life and economic consequences [1,2]. The role of grass pollen allergens in triggering immunoglobulin E (IgE)-mediated type I allergic diseases, such as allergic rhinitis, conjunctivitis, and bronchial asthma is very well established [3,4]. Epidemiologic studies have revealed that allergies to Bermuda grass (Cynodon dactylon; subfamily Chloridoideae) mainly affect people in warm tropical and sub-tropical areas of the world, such as southwestern United States, South Africa and northern and central Australia. Furthermore, approximately 27% of asthmatic patients in Taiwan ar