Der f 35: An MD-2-like house dust mite allergen that cross-reacts with Der f 2 and Pso o 2

BackgroundDermatophagoides farinae is a source of airborne house dust mite (HDM) allergens. We elucidated IgE-reactive allergens from D.farinae by two-dimensional immunoblotting-based allergenome analysis, and identified one new allergen, named Der f 35, that possesses IgE-binding capacity comparable to that of Der f 2. The aim of this study was to clarify the allergenic capacity of new HDM allergen Der f 35. MethodsWe cloned der f 35 from D.farinae mRNA and produced recombinant Der f 35 in Escherichia coli. The IgE-binding capacity of Der f 35 and its cross-reactivity with group 2 allergens from D.farinae and Psoroptes ovis were determined by enzyme-linked immunosorbent assay (ELISA) and ELISA inhibition assays, respectively. ResultsThe deduced amino acid sequence for der f 35, which possesses the MD-2-related lipid-recognition domain, showed higher identity with group 2 allergens from P.ovis (61.5%) and Blomia tropicalis (50.7%) than with Der f 2 (40.8%). Der f 35 showed IgE-binding frequencies of 77.5% (31/40) for the native form upon allergenome analysis and 51.4% (18/35) for recombinant structure by ELISA. Der f 35 showed cross-reactivity with Der f 2 and Pso o 2 in reaction with HDM-allergic patients' IgE by ELISA inhibition assay. ConclusionDer f 35 is a candidate major allergen from D.farinae, which is more similar to group 2 allergens from sheep scab mite and storage mites. Der f 35 could be responsible for the cross-reactivity among group 2 mite allergens.