Double-blind and placebo-controlled study to assess efficacy and safety of a modified allergen extract of Dermatophagoides pteronyssinus in allergic asthma.

BACKGROUND: A randomized double-blind, placebo-controlled study was conducted in patients allergic asthma sensitized to Dermatophagoides pteronyssinus. OBJECTIVE: To evaluate the efficacy and safety after 1-year of immunotherapy with a modified D. pteronyssinus extract compared with placebo. MATERIAL AND METHODS: Fifty-five patients were randomly allocated to receive the active treatment (n = 29), or placebo (n = 26). The main outcome was the specific bronchial provocation test (BPT). Other parameters analysed were dose-response skin prick test (SPT), symptom and medication scores and asthma quality of life (AQLQ). RESULTS: At the end of the study, the active group showed a significant increase in the PD(20)FEV(1) compared with placebo (P = 0.0029). Nineteen patients of the active vs 10 of the placebo group needed more than twice the initial amount of allergen extract to have a positive BPT (P = 0.0293); seven patients in the placebo vs one in the active group needed less than half (P = 0.0137). In SPT, a significant improvement (P = 0.0049) was found in the active group. This group also had a median reduction of 91.5% in symptom scores, whereas the placebo group increased by 86%. Medication scores decreased in both groups (56% in the active and 11.4% in the placebo). In AQLQ, the differences between both groups were significant (P = 0.0234) at the end of the study. CONCLUSION: After 1 year of treatment, the modified extract of D. pteronyssinus demonstrated to be safe and efficacious to treat patients with asthma and allergic rhinoconjunctivitis sensitized to this mite.

Comparison of Vespula germanica venoms obtained from different sources.

This study was carried out to compare the allergenic potency of Vespula germanica (VG) venoms extracted by different methods and commercially available venoms from Vespula species currently used for in vivo and in vitro studies including immunotherapy. Pure VG venom was used as the reference material. Protein content and enzymatic and allergenic properties of all venoms studied were determined by dye stain reagent, hyaluronidase and phospholipase A1B enzyme activities, and radioallergosorbent test inhibition studies, respectively. Radioallergosorbent test discs sensitized with commercial and pure VG venom were compared using specific IgE antibodies from subjects allergic to VG venom. The data obtained indicate that there were important differences in the allergenic potency between the Vespula species venoms employed for in vivo and/or in vitro assays, VG venom obtained by sac dissection, and pure VG venom. These results indicate that venoms from Vespula species used for in vitro and in vivo tests have a lower concentration of allergens and contain nonvenom proteins. These data should be taken into account when these vespid venoms are used for diagnostic purposes and also when evaluating immunotherapy studies.