Methods:
SDS-PAGE, immunoblots and high-resolution mass spectrometric analysis was performed with 16 house dust mite (HDM) SPT solutions and AVs from 3 Indian manufacturers. Authority-approved European SPT solutions and in-house extracts were used as references.

Results:
From the 5 Indian Dermatophagoides pteronyssinus products, none contained proteins from this source. Instead, 1 sample contained Dermatophagoides farinae and human serum proteins, 4 products contained allergens from the storage mite Suidasia medanensis, allergens from the legume Cicer arietinum (chickpea), and proteins from baker’s yeast. From 4 Indian D. farinae-labeled products, 2 contained human serum proteins and a limited number of D. farinae allergens. Two contained only Suidasia, Cicer, and yeast proteins. In contrast, the European authority-approved D. pteronyssinus and D. farinae SPT solutions that were used as reference in this study, contained exclusively proteins of the respective species and covered the expected allergen spectra. The Blomia tropicalis sample contained no Blomia allergens at all, but consisted exclusively of Suidasia, Cicer, and yeast proteins. All 6 HDM samples consisted of human serum proteins and limited amounts of D. farinae allergens.

Conclusions:
All commercial Indian SPT solutions and AVs analyzed in this study are not suitable for dust mite allergy diagnosis and therapy, as they contain either no, or only a limited number of,  HDM allergens. In addition, their use could lead to misdiagnosis since some of them contain allergens from other sources, including the storage mite Suidasia, chickpea, as well as baker’s yeast. Further, their application might be harmful to patients, as some products contain large amounts of proteins of human origin. Analysis of European SPT solutions, on the other hand, confirmed their suitability for dust mite allergy diagnosis.