Immunoglobulin E reactivity of recombinant allergen Tyr p 13 from Tyrophagus putrescentiae homologous to fatty acid binding protein

The storage mite, Tyrophagus putrescentiae, is one of the important causes of allergic disorders. Fifteen allergenic components were demonstrated in storage mite by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting, but only the group 2 allergen Tyr p 2 has been cloned and characterized. In this study, we attempted to identify and characterize new allergens from T. putrescentiae, which is a dominant species of storage mite in Korea. Expressed sequence tags were analyzed to identify possible storage mite allergens, and the cDNA sequence encoding a protein homologous to fatty acid binding protein, a mite group 13 allergen, was identified and named Tyr p 13. Its deduced amino acid sequence showed 61.1 to 85.3% identity with other mite group 13 allergens. The recombinant protein was expressed in Escherichia coli using a pET 28b vector system, and its allergenicity was investigated by enzyme-linked immunosorbent assay (ELISA). The recombinant allergen was detected in 5 of 78 (6.4%) T. putrescentiae-positive sera tested, and it inhibited 61.9% of immunoglobulin E binding to crude extract at an inhibitor concentration of 10 μg/ml by inhibition ELISA using serum from the patient who showed the strongest reaction by ELISA. In this study, a novel allergen was identified in T. putrescentiae. This allergen could be helpful for more-detailed characterizations of storage mite allergy.