Isolation and characterization of the mountain cedar (Juniperus ashei) pollen major allergen, Jun a 1

Background: Cedar pollens are important causes of seasonal allergic disease in diverse geographic areas. Objective: A major allergen from mountain cedar (Juniperus ashei) pollen, t ermed Jun a 1, was isolated and characterized. Methods: Water-soluble pollen glycoproteins were extracted, salt precipitat ed, and purified with use of concanavalin A affinity chromatography or HPLC . The purified fractions were characterized by SDS-PAGE, immunoblotting, an d N-terminal amino acid sequence analysis. Binding of allergen-specific IgE from the sera of cedar-hypersensitive patients was detected by ELISA and a ntigen-specific responses of peripheral blood T cells by tritiated thymidin e incorporation. Results: The major extractable cedar pollen glycoprotein had a molecular we ight and N-terminal amino acid sequence that was similar to that of the maj or allergen Cha o 1, from Japanese cypress (Chamaecyparis obtusa), and Cry j 1, from Japanese cedar (Cryptomeria japonica). IgE from cedar-hypersensit ive patients' sera bound to the isolated glycoprotein, Conclusion: The predominance of Jun a 1 in the soluble proteins of mountain cedar pollen and its high degree of homology with Cha o 1 and Cry j 1 make it likely to be the major allergen of this pollen. Amino acid sequence con servation also makes Jun a 1 a potential target for cross-reactivity betwee n these pollen allergens. The observed reactivity of IgE from the sera of J apanese cedar-sensitive patients with Jun a 1 is consistent with this propo sition.