Characterization of group 1 major allergen of Quercus mongolica, Que m 1

Abstract

Background Oak, which belongs to Fagales family and the pollen is the main cause for spring pollinosis in Korea. white oak pollen has been being used for diagnosis and treatment of spring pollinosis, even though it is not native species in Korea. Group 1 major allergen, which belong to pathogenesis-related protein-10 (PR-10) comprises of 80% of total allergenicity of Fagales pollens and it is considered as the most important major allergen for Fagales pollinosis. Therefore, we produced and investigated the allergenicity of group 1 major allergen of mongolian oak, which is the prevalent oak species in Korea.

Methods A putative Que m 1 was cloned by RT-PCR, and expressed in Escherichia coli. IgE binding reactivity to the recombinant proteins, along with commercial Bet v 1, were assessed using enzyme-linked immunosorbent assay (ELISA) with the 50 sera of Korean Fagales pollinosis patients.

Results Que m 1 consist of 160 amino acids, with calculated molecular weight (MW) of 17,292 Da and the isoelectric point is 5.37. Que m 1 shares 96.2% amino acid sequence identity with Que a 1. However, Que m 1 showed higher specific IgE reactivity than Que a 1 in Korean Fagales pollinosis patients (90.0% vs. 78.0%). For diagnosis of Korean Fagales pollinosis, area under the curve of Que m 1 sIgE was higher than that Que a 1 in ROC analysis. Bet v 1 sIgE was higher than these oak pollen group 1 major allergens and its positive rate (94.0%). In IgE inhibition blotting analysis, recombinant Que m 1 completely inhibited IgE response to about 17 kDa allergen of mongolian oak extract, while it was partially inhibited by recombinant Que a 1. Que m 1 seems to be a major cause for oak allergy in Korea.

Conclusion We cloned and produced recombinant group 1 major allergen of Quercus mongolica (Que m 1), which may be potentially useful for the diagnosis and treatment of Fagales pollinosis in Korea. It showed strong cross-reactivity with other allergenic PR-10 molecules from oak and birch, and had better clinical values than Que a 1 for diagnosis of Korean Fagales pollinosis.