Double‐blind, placebo‐controlled Alternaria alternata immunotherapy: in vivo and in vitro parameters

Abstract

Few studies have been published on the efficacy and safety of immunotherapy with fungal extracts, possibly because of difficulties arising from antigenic variability among different strains of fungus. The aim of the study was to analyze changes in the in vivo and in vitro parameters in response to immunotherapy with an Alternaria alternata extract. We studied 28 patients with rhinitis, bronchial asthma, or both caused by Alternaria. The patients were randomized to the active immunotherapy or placebo group, and a conventional schedule of immunotherapy was used. We recorded changes for a year in skin reactivity (skin prick test), conjunctival reactivity (conjunctival provocation test), and in vitro parameters (serum-specific IgE, IgG, IgG1 and IgG4 for A. alternata complete extract and for natural and recombinant Alt a 1). Twenty-three patients completed the study and all attained the maintenance dose. There were no changes in skin reactivity in the active treatment group, and reactivity increased at the end of the study period in the placebo group. Conjunctival sensitivity decreased only in the active treatment group when the maintenance dose was reached. Allergen-specific IgE decreased, and IgG, IgG1 and IgG4 increased in all periods of study in the active treatment group, with no changes in the placebo group. Allergen-specific immunotherapy with the A. alternata extract tested here led to a decrease in conjunctival reactivity and induced a significant immunologic response.