Immune responses to Aspergillus in cystic fibrosis

Aspergillus fumigatus (Af) is well recognized in its ability to colonize the respiratory tract in cystic fibrosis (CF). Furthermore, a number of the immune responses of the patient with CF to this organism have been characterized, and the immune inflammatory response to Af may result in allergic bronchopulmonary aspergillosis (ABPA). This study evaluated a series of immunologic parameters in 75 patients with CF in order to characterize more fully the spectrum of immune responses of those patients to Af and to clarify the relationship of those responses to the clinical features of ABPA. The patients could be classified into four groups, depending on the clinical and immunologic findings. Eight (10.7%) of the 75 patients had clinical and laboratory evidence of ABPA, including immediate cutaneous reactivity to Af, eosinophilia, elevated total serum IgE, elevated serum IgE-Af or IgG-Af, and precipitating antibody to Af. Ten (13.3%) patients had these features, except that the total serum IgE level was within the normal range. Forty (53.5%) of the patients had no significant criteria for ABPA but had varying immunologic responses to Af, such as immediate cutaneous reactivity to Af in 25 patients and elevated serum IgE-Af and/or IgG-Af in 19 patients. Seventeen (22.7%) patients had no evidence of an immunologic response, as determined by skin testing and serologic assays. The study demonstrated that the response of patients with CF to Af ranges from clinically apparent ABPA to a possible variant of ABPA, to a nondiagnostic group of features consistent with sensitization to Af or to no characteristic immune response.