Identification of a chemotactic, MCP-1-like protein from Mycobacterium avium.
In the immunocompetent host, Mycobacterium avium is responsible for chronic localized pulmonary disease, which is characterized by the presence of increased numbers of activated T cells and macrophages in the lungs. M. avium organisms as well as sonic extracts of M. avium were found to act as chemoattractants for THP-1 cells as well as monocytes, monocyte-derived macrophages and alveolar macrophages obtained from normal human donors in an in vitro chemotaxis assay, where a significantly higher number of cells were found in wells containing M. avium compared to control wells. Proteolytic treatment of M. avium sonicate resulted in significant loss (50%) of chemotactic activity. Monoclonal antibodies against recombinant human monocyte chemoattractant protein-1 (MCP-1) were found to cross-react with a 34-kDa protein of M. avium sonicate on Western blot and inhibit M. avium sonicate-mediated chemotaxis of THP-1 cells (47%). These data suggest the presence of an 'MCP-1 like' molecule on M. avium. Recruitment of host immune regulatory cells to the site of infection by pathogens may be involved in generating a local immune response or may be a bacterial strategy for survival within the host by recruiting the cells that they infect, i.e. macrophages.
Rao
Savita P
SP
Department of Medicine, Division of Pulmonary and Critical Care Medicine, University of California San Diego, 200, W. Arbor Drive, San Diego, CA 92103-8374, USA. srao@ucsd.edu
Hayashi
Tomoko
T
Catanzaro
Antonino
A
D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000378:metabolism*; D002634:Chemotaxis, Leukocyte; D006801:Humans; D016676:Macrophages, Alveolar / Q000276:immunology* / Q000382:microbiology; D009000:Monocytes / Q000276:immunology* / Q000382:microbiology; D015269:Mycobacterium avium Complex / Q000276:immunology / Q000378:metabolism*; D015270:Mycobacterium avium-intracellulare Infection / Q000382:microbiology
D018932:Chemokine CCL2