COMPARISON OF THE LEVELS OF THE MAJOR ALLERGENS DER-P-I AND DER-P-II IN STANDARDIZED EXTRACTS OF THE HOUSE-DUST MITE, DERMATOPHAGOIDES-PTERONYSSINUS

Allergy to the house dust mite Dermatophagoides pteronyssinus is media ted by IgE to the major allergens Der p I and Der p II in the majority of mite-allergic patients. In recent years, standardized preparations of D. pteronyssinus, commercially available from several sources, hav e become widely used for the diagnosis and immunotherapy of mite aller gy. As standardization implies uniformity of allergen composition and potency, we directly compared the absolute and relative quantities of Der p I and Der p II in six different commercial standardized extracts of D. pteronyssinus. Our findings reveal variability in levels of bot h Der p I and Der p II, producing ratios of Der p I/Der p II ranging f rom 1.1/1 to 6/1. Although the content of minor allergens in the extra cts was not evaluated here, their contribution to the overall reactivi ty of mite-allergic patients to the commercial extracts was judged to be minimal. This was demonstrated by showing that plasma depleted of r eactivity to both Der p I and Der p II had virtually no residual IgE d irected against extract components. The variation in the proportion of Der p I and Der p II among different D. pteronyssinus extracts is lik ely to influence their biological effectiveness. Patients with reactiv ity against only Der p I or Der p II, who were found to comprise appro ximately one-third of the mite-allergic population, may not respond op timally to extracts containing relatively low levels of the allergen t o which they are sensitive.