Application of the First International Standard of Dermatophagoides pteronyssinus (House Dust Mite) in the Evaluation of Allergen Extracts Produced from Two Different Source Materials

The first international standard (IS) of the house dust mite Dermatophagoides pteronyssinus was used to compare side-by-side two allergen extracts prepared from two different house dust mite sources, namely whole mite cultures (WMC) and purified mite bodies (PMB), by employing several biochemical and immunochemical methods. In most methods employed, IS and WMC resembled more to each other than to PMB. These similarities comprehend protein contents, protein patterns, antigen and allergen patterns as well as total in vitro activity obtained in RAST inhibition (RI). The differences between WMC and PMB could be reproduced in different batches. Standardization in relation to IS of D. pteronyssinus yields activity ratios ranging from 2.4 to 70.1 between WMC and PMB depending on the variation of RI employed, indicating quantitative differences between the two preparations. When coupled to BrCN activated paper disks and employed in direct RAST, both preparations yielded almost identical binding values of specific IgE. Also in skin prick test, WMC and PMB produced very similar results in 12 mite-allergic patients. It was not possible to differentiate between the two preparations when used in concentrations which are usually employed for diagnostic purposes. These findings demonstrate the diversity of allergens in mite extracts derived from different sources and reveal the problems which are involved with the use of the WHO D. pteronyssinus IS.