Expression, purification and characterization of Der f 27, a new allergen from dermatophagoides farinae

The house dust mite (HDM), Dermatophagoidesfarinae (D. farina), is one of the most important indoor allergen sources and a major elicitor of allergic asthma; itscharacterization is important in the diagnosis and immunotherapy of mite allergen-relevant diseases. This study aims to characterize a novel allergen, the D. farinae-derived serpin (Der f 27). In this study, the total RNA of D. farinae was extracted, and the Der f 27 gene was cloned and expressed. The allergenicity of recombinant Der f 27 protein was determined by enzyme-linked immunosorbent assay, and Western-blotting with the sera of asthma patients, and skin prick test (SPT) in allergic human subjects. A r-Der f 27 allergic asthma mouse model was established. The cloned Der f 27 gene has been presented at the Gene Bank with an accession number of KM009995. The IgE levels of r-Der f 27 in the serum from r-Der f 27 SPT positive allergic patients were 3 folds more than healthy subjects. The Der f 27 SPT positive ratewas 42.1% in 19 DM-SPT positive patients. Airway hyperresponsiveness, serum specific IgE, and levels of interleukin-4 in the spleen cell culture supernatant were significantly increased in allergic asthma mice sensitized to r-Der f 27. In conclusion, Der f 27 is a new subtype of house mite allergen.