Eosinophil extracellular traps in allergic bronchopulmonary aspergillosis airways

<bold>Background:</bold> Eosinophil extracellular traps (EETs) are observed in allergic bronchopulmonary aspergillosis (ABPA) airways. However, EETs quantification and its relevance with clinical features of ABPA patients have not been elucidated. <bold>Methods:</bold> Twenty-eight inpatients with acute stage ABPA complicating asthma and 32 with non-cystic fibrosis bronchiectasis complained of productive cough were enrolled. We measured the concentration of cell-free DNA (cfDNA) by PicoGreen assay, eosinophil cationic protein (ECP)-DNA complexes by sandwich ELISA in bronchoalveolar lavage fluid (BALF) from both groups. <bold>Results:</bold> Patients with ABPA presented higher levels of ECP-DNA concentrations in the airway than pure bronchiectasis (p=0.011). In ABPA group, airway cfDNA level was closely linked to serum Aspergillus fumigatus-specific IgG (r=0.883, p=0.002), ECP (r=0.607, p=0.003) and ECP-DNA (r=0.672, p<0.001) in BALF, whereas it was negatively related to spirometry especially to peak expiratory flow (PEF)%pred (r=-0.574, p=0.003). Alveolar EET presence was associated with ECP (r=0.568, p=0.007) and Charcot Leyden Crystal protein (r=0.656, p=0.002) in BALF. When stratified ABPA patients by HRCT findings, the concentration of airway cfDNA and ECP-DNA significantly increased in the ABPA-HAM group (presence of high-attenuation mucus) than that of ABPA-S (seropositive without demonstrable abnormalities on HRCT) group（p<0.001 and p=0.003 respectively）. <bold>Conclusions:</bold> ABPA patients, ABPA-HAM in particular, bear higher airway EETs burden, which is closely correlated with Th2 inflammation markers while negatively related to lung function.