Significant improvement of specific bronchial hyperreactivity in asthmatic children after 4 months of treatment with a modified extract of dermatophagoides pteronyssinus.

BACKGROUND The clinical efficacy of allergen immunotherapy using therapeutic vaccines containing modified allergen extracts has been previously shown. OBJECTIVE To evaluate the clinical efficacy of a vaccine containing depigmented, polymerized extract of Dermatophagoides pteronyssinus in asthmatic children, monosensitized to mites, after 4 months of treatment. MATERIAL AND METHODS A total of 30 mite-allergic, asthmatic children (age range, 8-16 years) were entered in the study; 15 were treated with the modified allergen extract (active group) and 15 received only pharmacologic treatment (control group). The study was open, controlled and parallel with random allocation of the patients to each of the groups. Efficacy was evaluated using allergen-specific bronchial challenge tests, dose-response skin-prick tests, and symptom and medication scores. The results of the bronchial challenges and dose-response skin-prick tests were compared at baseline and after 4 months of treatment. The build up phase consisted of 4 injections in 2 days, followed by 4 injections of the maintenance dose. RESULTS All patients of the active group concluded the study, whereas 2 of the control group did not. In the active group, there was a significant difference in the PC20FEV1 (P <.01) after 4 months. The mean allergen quantity needed was 26 microg at baseline vs. 309 microg after 4 months (a 12.8-fold increase). There was no difference in the control group (5 tg at baseline vs 8 microg at the end). A significant reduction in the number of cases with dual bronchial response was observed in the treated group (P < .05). Two treated patients of this group experienced a negative bronchial challenge after 4 months of treatment. The group of active patients also experienced significant improvement in skin reactivity and symptom and medication scores. CONCLUSIONS Vaccines containing depigmented polymerized extracts of D pteronyssinus are safe and effective in the treatment of mite allergic asthmatic children, and provide clinical benefit after 4 months of treatment.