Standardization of house dust mite extracts in Korea

Purpose: House dust mites are the most important cause of respiratory allergy in Korea. Standardization of allergen extracts is essential for improving diagnostics and immunotherapeutics. This study was undertaken to evaluate the allergenicity of standardized house dust mite allergen extracts from Korean house dust mite isolates. Methods: Allergen extracts were prepared from cultured Korean house dust mites (Dermatophagoides farinae and D. pteronyssinus). Allergenic activities of Korean house dust mite extracts were compared to standardized extracts from a company in the United States whose allergen concentrations were expressed as Allergy Units (AUs). Specifically, we compared group 1 and 2 major allergens using two-site enzyme-linked immunosorbent assay (ELISA) kits and an in vivo intradermal test. Results: Major allergen concentrations were 17.0 μg/mg (5.0 μg/mg of Der f 1 and 12.0 μg/mg of Der f 2) for a D. farinae extract and 24.0 μg/mg (11.6 μg/mg of Der p 1 and 12.4 μg/mg of Der p 2) for a D. pteronyssinus extract. Using chloramphenicol (CAP) inhibition assays, AUs were 12.5 AU/μg for a D. farinae extract and 12.8 AU/μg for a D. pteronyssinus extract. Allergenic activities were 3- to 4-fold stronger when assessed by intradermal skin tests for in vivo standardization. Conclusions: Allergen extracts were prepared from Korean house dust mites and the allergenicities of the extracts were estimated using AU measurements. House dust mite extracts prepared in this study could be utilized as a reference material, which will be useful for the development of diagnostic and immunotherapeutic reagents in Korea.