Bronchoscopic microsampling to analyze the epithelial lining fluid of patients with pulmonary Mycobacterium avium complex disease

Background: A new bronchoscopic microsampling (BMS) probe has recently been developed, which allows the minimally invasivecollection of epithelial lining fluid (ELF) simultaneously from multiple sites. While the number of immunocompetent patients with pulmonary Mycobacterium avium complex(MAC) disease is growing, the precise pathogenesis of the disease remains to be clarified. Objectives: This study aimed to measure biochemical markers in the ELF of patients with pulmonary MAC disease using BMS. Methods: We studied 8 healthy volunteers (controls) and 8 patients with pulmonary MAC disease. In the patients, ELF was collected from visibly abnormal (involved) and normal (uninvolved) sites using high-resolution computed tomography (HRCT). Results: The concentration of IFN-γ (means ± SEM) was significantly higher in patient ELF sampled from involved (26.62 ± 9.66 pg/ml) than from uninvolved sites (5.33 ± 1.44 pg/ml; p < 0.05) or from normal controls (<1.56 pg/ml; p < 0.05). In most patients, there was no difference in IFN-γ concentrations between the involved and uninvolved sites. The concentration of KL-6 in ELF was significantly higher in the involved (793 ± 108 U/ml) than in the uninvolved sites (192 ± 43 U/ml;p < 0.05) or in normal controls (186 ± 38 U/ml;p < 0.05). Conclusions: The specific inflammatory reaction caused by MAC infection might not be limited to sites that were visibly abnormal on HRCT. Although further improvement has to be considered, BMS may help to increase the understanding of the pathogenesis of various respiratory disorders.