Clinical and immunologic evaluation of tyrosine-adsorbed Dermatophagoides pteronyssinus extract: A double-blind placebo-controlled trial

Abstract

We evaluated the clinical efficacy and immunologic changes associated with the administration of tyrosine-adsorbed Dermatophagoides pteronyssinus (Dpt) extract. The study was carried out in a double-blind, placebo-controlled fashion in 18 patients with Dpt-induced asthma during a trial period of at least 12 mo. Patients initially received six increasing doses once a week; the top dose of 400 Noon units was repeated at monthly intervals. Clinical response was on the basis of diary cards on which symptoms and medication scores were recorded; daily lung function measurements were made by use of a mini Wright's peak flow meter. The entire spectrum of physiologic measurements, medications, and symptoms were taken into account by computing daily scores over a 2-week period. Total IgE, Dpt-specific IgE antibodies, and leukocyte histamine release were measured before treatment and during hyposensitization. Changes in Dpt-specific IgG were evaluated with a double antibody antigen-binding assay by use of the purified fraction of mite extract F 4 P 1 . All patients had measurable levels of IgG antibodies to F 4 P 1 before treatment. Treatment with tyrosine-adsorbed Dpt extract resulted in a significant increase of specific-IgG antibodies in the treated group at 2 and 6 mo only (nonparametric rank sum test). Variations relative to the pretreatment values of total and specific IgE were not significantly different in the treated and in the control patients after 2.6 and 12 mo. No significant decrease in leukocyte sensitivity was observed after treatment. It was only possible to demonstrate a significant diminution in the mean medication score (nonparametric sign test) in the first 6 mo for the treated group; independently of the beginning of the treatment, the treated group demonstrated a reduction of the mean medication score and an improvement in peak expiratory flow rate lung function before the midsummer months when seasonal increase in mite density can occur. Particular attention was paid to the methodological problems raised during this study and inherent in a trial in house dust-mite asthma.