Immunotherapy with a standardized Dermatophagoides pteronyssinus extract. I. In vivo and in vitro parameters after a...

Dermatophagoides pteronyssinus (Dp) is the major allergen in allergic asthma in France. Standardized and lyophilized Dp extracts are available, and their effectiveness after a short course of rush immunotherapy was examined in a placebo-controlled, double-blind study. Twenty patients received the Dp standardized extract, and 10 other patients received a placebo extract. Before and 7 weeks after rush immunotherapy, in vivo and in vitro parameters were examined. Bronchial provocation tests performed in a standardized manner demonstrated that a provocative dose causing a 20% fall in FEV1, a 25% fall in maximum mild expiratory flow rate, a 25% fall in maximum flow when 50% of the forced vital capacity has been expired, and a 35% fall in specific airway conductance were significantly (p less than 0.005 to p less than 0.01, Wilcoxon W test) improved in the treated group and remained unchanged in the placebo group. Skin test titration demonstrated that patients placed in the treated group had a significant (p less than 0.001, Wilcoxon W test) decrease of both end point titer and size of the largest wheal. No significant difference was observed in the placebo group. Serum Dp-IgE did not vary significantly in either group. Serum Dp antigen P1-IgG was significantly (p less than 0.001, Wilcoxon W test) increased in the treated group and slightly increased in the placebo-treated group. This study demonstrated that a Dp standardized extract administered by a rush protocol elicits a rapid and significant immune response and leads to a significant protection of the patients.