Recombinant allergens combined with biological markers in the diagnosis of allergic bronchopulmonary aspergillosis in cystic fibrosis patients.

Allergic bronchopulmonary aspergillosis (ABPA) is a frequent complication in cystic fibrosis patients. The diagnosis remains difficult and requires a combination of clinical, radiological, biological, and mycological criteria. The aim of this study was to analyze the added value of two recombinant antigens, rAspf4 and rAspf6, associated with the detection of specific IgG; precipitins; total IgE; and Aspergillus fumigatus in sputum for the diagnosis of ABPA. In a retrospective study, we determined the specific IgE responses to these recombinants in 133 sera of 65 cystic fibrosis patients. We selected an average of five serum samples from each of the 17 patients with ABPA (13 proven and 4 probable ABPA) and from 3 patients with Aspergillus bronchitis and rhinosinusitis. One serum sample for the 45 patients without ABPA was tested. The sensitivity of specific IgE detection against rAspf4 calculated per patient (92.3%) was significantly higher (P < 0.05) than that of rAspf6 (53.8%). When rAspf4 IgE detection was associated with anti-Aspergillus IgG enzyme-linked immunosorbent assay (ELISA) and precipitin detection, the sensitivity rose to 100%. The specificities of rAspf4 and rAspf6 IgE detection were 93.7% and 91.6%, respectively. Other diagnostic criteria had slightly lower specificities (87.5% for anti-Aspergillus IgG ELISA, 89.6% for precipitins, 84.4% for total IgE, and 85.0% for positive A. fumigatus culture in sputum). In conclusion, this retrospective study showed the relevance of rAspf4 IgE detection, in combination with other biological markers (Aspergillus IgG ELISA, precipitins, and total IgE), for improving the biological diagnosis of ABPA.