Pulmonary Function Tests of Mycobacterium avium-intracellulare Infection: Correlation with Bronchoalveolar Lavage Fluid Findings

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Background: The pulmonary Mycobacterium avium-intracellulare (MAI) infection in patients with neither predisposing lung disease nor immunodeficiency is recognized to occur predominantly in older or middle-aged and thin females, and has characteristic chest computed tomography (CT) findings with multiple nodules and bronchiectasis. Objective: To investigate the pathophysiology with and individual of MAI infection with neither predisposing lung disease nor immunodeficiency. The bronchoalveolar lavage (BAL) fluid (BALF) was recovered directly from the affected segments identified by the chest CT. Methods: We performed a pulmonary function test (PFT) and BAL in 15 patients (all females) with MAI infection and 5 normal female volunteers. Results: The residual volume and the slope of phase III (ΔN₂) were significantly increased and v̇₂₅ was significantly decreased in the 15 patients compared with the normal control subjects. The patients’ BALF showed significant increases in neutrophils and activated CD4 lymphocytes, proinflammatory cytokines, and neutrophil elastase (NE) compared to those in the controls. We analyzed the PFT and BALF findings, and observed a significant correlation between the ΔN₂ and interleukin (IL)-8 concentration (r = 0.65, p < 0.01), IL-8/albumin ratio (r = 0.51, p < 0.05) and NE/albumin ratio (r = 0.57, p < 0.05) in the BALF and ΔN₂, respectively. Conclusions: These findings suggest that small airway dysfunction in MAI infection without predisposing lung disease is related to the inflammation probably related to the neutrophil.