Clinical strains of Mycobacterium avium isolated from patients with acquired immunodeficiency syndrome, but not a non-clinical laboratory strain (ATCC 25291), were found to stimulate the human alveolar epithelial cell line A549, to produce monocyte chemoattractant protein (MCP)-1. A549 cells were also found to produce elevated levels of MCP-1 in response to sonicates of the clinical strains of M. avium, and surprisingly, the non-clinical strain as well. However, sonic extracts of the clinical strains were found to induce significantly higher levels of MCP-1 production compared to extracts of the non-clinical strain (P < 0.001). These data suggest the existence of strain- related differences in antigen expression by M. avium. The clinical and non- clinical strains of M. avium were found to attach and invade, but not replicate in A549 cells indicating that MCP-1 production by A549 cells does require the presence of viable, replicating organisms. Activation of alveolar epithelial cells by exposure to M. avium resulting in the production of chemokines which recruit inflammatory cells to the site of infection may be an important regulatory pathway for the activation of pulmonary host defense. (C) 2000 Federation of European Microbiological Societies.
Bibliographical noteFunding Information:
This research was aided by grants from the UCSD Center for AIDS Research (NIAID 5 P30 AI36214), the American Lung Association (RG-082-N) and American Lung Association of California–Research Program to S.P.R. We thank Drs. Richard S. Kornbluth and Pascal R. Meylan for providing us with M. avium strain (I13).
- Alveolar epithelial cell
- Monocyte chemoattractant protein-1
- Mycobacterium avium