Immunotherapy with mosquito ( Culex quinquefasciatus) extract: a double-blind, placebo-controlled study

Abstract

Mosquito allergy is well established, but mosquito immunotherapy requires validation using clinical and immunologic variables. To evaluate the tolerability and efficacy of specific immunotherapy with Culex quinquefasciatus (mosquito) extract. We performed a randomized, double-blind, placebo-controlled trial of immunotherapy for 1 year in 40 patients with asthma, rhinitis, or both. Patients were evaluated by means of intradermal testing, symptom and drug scores, and histamine provocation testing before and after 1 year of immunotherapy. Mosquito specific IgE and IgG subclass antibody responses were evaluated at the basal level and after 1 year. Patients receiving allergen immunotherapy for 1 year showed a significant improvement compared with baseline and patients receiving placebo regarding skin reactions, symptom scores (rhinitis and asthma), and forced expiratory volume in 1 second. Provocation concentration of histamine that caused a decrease in forced expiratory volume in 1 second of 20% by inhalation was elevated in the group receiving immunotherapy. In the active group serologic analysis showed a slight reduction in IgE levels (P = .02) but a significant elevation in IgG4 levels (P = .001), with a significant decrease in the IgE/IgG4 ratio (P = .001). All these changes in the placebo group were nonsignificant. Allergen immunotherapy with mosquito extract was well tolerated, with improvement in symptoms and airway reactivity. Good clinical outcome was associated with increased IgG4 antibody levels.