Analysis of BAL fluid in M. avium-intracellulare infection in individuals without predisposing lung disease.

The purpose of this study was to investigate the characteristics of pulmonary inflammation caused by Mycobacterium avium-intracellulare (MAI) in individuals with neither predisposing lung disease nor immunodeficiency. We reviewed the records of 20 patients with pulmonary MAI infection (including 19 female patients) whose past history and previous chest radiographs revealed no predisposing lung disease. We analysed the bronchoalveolar lavage fluid (BALF) from these 20 patients and from six normal female controls. The BALF was recovered directly from the relevant segment that was identified with chest-computed tomography. The BALF cell profiles showed significantly elevated counts for total cells, lymphocytes and neutrophils, but the macrophage cell count was not elevated. The CD4+ lymphocyte count and CD4+/CD8+ ratio were significantly increased compared with those in the controls. The lymphocytes demonstrated phenotypical evidence of activation, with increased expression of human leukocyte antigen-D-related antigen (HLA-DR). The tumour necrosis factor-alpha, interleukin (IL)-1beta, IL-6 and IL-8 concentrations were significantly increased. The neutrophil elastase concentration was also increased, and it was significantly correlated with the neutrophil cell count in the BALF. These findings suggest that the increased counts of activated CD4+ lymphocytes and neutrophils and the elevated concentrations of proinflammatory cytokines and neutrophil elastase appear to be common characteristics in Mycobacterium avium-intracellulare infection.