Aspergillus fumigatus components distinguish IgE but not IgG4 profiles between fungal sensitization and allergic broncho‐pulmonary aspergillosis

Aspergillus fumigatus is the causative agent of allergic broncho‐pulmonary aspergillosis. Prompt and accurate diagnosis may be difficult to achieve with current clinical and laboratory scores, which do not include immune responses to recombinant A. fumigatus allergens. We measured specific immunoglobulin E and G4 directed to recombinant A. fumigatus allergens in 55 cystic fibrosis patients without allergic broncho‐pulmonary aspergillosis but sensitized to A. fumigatus and in nine patients with allergic broncho‐pulmonary aspergillosis (two with cystic fibrosis and seven with asthma). IgG4 responses to recombinant A. fumigatus allergens were detected in all patients, but neither prevalence nor levels were different between the two patient groups. On the other hand, both prevalence and levels of IgE responses to Asp f 3, Asp f 4, and Asp f 6 helped distinguish allergic broncho‐pulmonary aspergillosis from A. fumigatus sensitization with good negative and positive predictive values.