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Keywords:

  • Asthma;
  • ELISA;
  • immunoblot;
  • immunotherapy;
  • Periplaneta americana;
  • rhinitis

Eur J Clin Invest 2011; 41 (8): 879–888

Abstract

Background  Cockroach proteins induce allergies including asthma in predisposed individuals. Well-designed controlled studies are required to show the effect of cockroach immunotherapy (IT). This study is aimed to assess changes in clinical and immunological parameters post-IT with Periplaneta americana extract.

Materials and methods  A double-blind, placebo-controlled trial of cockroach IT was performed for 1 year in 50 patients of asthma, rhinitis or both. The efficacy of IT was assessed by change in skin reactivity and clinical parameters such as symptom/drug score, airway reactivity and immunological parameters namely IgE, IgG1 and IgG4, IL-4 and IFN-γ by enzyme-linked immunosorbent assay and western blotting using patients’ sera at baseline and after 1 year of treatment.

Results  Immunotherapy with cockroach extract demonstrated significant improvement in clinical parameters of active group patients compared with baseline values and placebo group. Specific IgE levels showed a modest reduction, while IgG4 levels increased significantly in active IT group after 1 year. IgE immunoblotting demonstrated reduction in intensity and number of specific bands, whereas IgG4 binding showed more number and distinct bands following IT. Active group patients showed correlation between increase in IgG4/IgG1 ratio and reduction in symptom score post-IT.

Conclusions  Immunotherapy with cockroach extract improved clinical and immunological status of asthma and rhinitis patients. Clinical improvement in patients after IT is associated with immunological changes.