Differential IgE recognition of recombinant Aspergillus fumigatus allergens by cystic fibrosis patients with allergic bronchopulmonary aspergillosis or Aspergillus allergy

Allergic bronchopulmonary aspergillosis (ABPA), an intense inflammatory reaction to Aspergillus in the lung, is recognized as a severe complication in patients with cystic fibrosis (CF). The diagnosis of ABPA in CF patients sensitized to Aspergillus fumigatus is complicated by interfering laboratory and clinical findings shared by the diseases. We have used cDNA encoding A. fumigatus allergens which were cloned from a cDNA library displayed on phage surface to produce recombinant proteins in Escherichia coli. Differential IgE responses to the allergens in A. fumigatus-sensitized CF patients with or without ABPA and CF controls without sensitization to A. fumigatus were demonstrated. A secreted ribotoxin (rAsp f 1) and a peroxisomal protein (rAsp f 3) were recognized by sera from A. fumigatus-sensitized CF-patients with or without ABPA. An intracellular manganese superoxide dismutase (rAsp f 6) and rAsp f 4, a protein with unknown function, were recognized exclusively by IgE from sera of CF patients with ABPA. Therefore, Asp f 4 and Asp f 6 represent specific markers for ABPA and allow a sensitive, fully specific diagnosis of the disease. The data suggest distinct IgE responses to colonization of the bronchial tree in CF patients with ABPA or A. fumigatus allergy and therefore a differential recognition of the pathogen in the two IgE-related inflammatory diseases.