The CD14 receptor does not mediate entry of Mycobacterium tuberculosis into human mononuclear phagocytes

Prior reports have suggested that CD14 mediates uptake of Mycobacterium tuberculosis into porcine alveolar macrophages and human fetal microglia, but the contribution of CD14 to cell entry in human macrophages has not been studied. To address this question, we used flow cytometry to quantify uptake...

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Bibliographic Details
Published in:FEMS immunology and medical microbiology 2003-05, Vol.36 (1), p.63-69
Main Authors: Shams, Homayoun, Wizel, Benjamin, Lakey, David L, Samten, Buka, Vankayalapati, Ramakrishna, Valdivia, Raphael H, Kitchens, Richard L, Griffith, David E, Barnes, Peter F
Format: Article
Language:English
Subjects:
Bacteria
Bacteriology
Biological and medical sciences
Cell marker
Cells, Cultured
Flow Cytometry
Fundamental and applied biological sciences. Psychology
Green Fluorescent Proteins
Humans
Immunomagnetic Separation
Invasion
Lipopolysaccharide Receptors - immunology
Luminescent Proteins - metabolism
Macrophage
Macrophages, Alveolar - immunology
Microbiology
Microscopy, Fluorescence
Monocytes - immunology
Mycobacterium tuberculosis - immunology
Pathogenicity, virulence, toxins, bacteriocins, pyrogens, host-bacteria relations, miscellaneous strains
Tuberculosis, Pulmonary - immunology
Tuberculosis, Pulmonary - microbiology
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Summary:Prior reports have suggested that CD14 mediates uptake of Mycobacterium tuberculosis into porcine alveolar macrophages and human fetal microglia, but the contribution of CD14 to cell entry in human macrophages has not been studied. To address this question, we used flow cytometry to quantify uptake by human monocytes and alveolar macrophages of M. tuberculosis expressing green fluorescent protein. Neutralizing anti-CD14 antibodies did not affect bacillary uptake and the efficiency of bacillary entry was similar in THP-1 cells expressing low and high levels of CD14. However, most internalized bacteria were found in CD14+ but not in CD14− monocytes because M. tuberculosis infection upregulated CD14 expression. We conclude that: (1) CD14 does not mediate cellular entry by M. tuberculosis; (2) M. tuberculosis infection upregulates CD14 expression on mononuclear phagocytes, and this may facilitate the pathogen’s capacity to modulate the immune response.
ISSN:0928-8244
1574-695X
DOI:10.1016/S0928-8244(03)00039-7