Decreased Sialidase Activity in Alveolar Macrophages of Guinea Pigs Exposed to Coal Mine Dust

• Published in: Environmental health perspectives Vol. 97; pp. 103 - 107
• Main Authors: Terzidis-Trabelsi, Hélène, Lefèvre, Jean Pierre, Bignon, Jean, Lambré, Claude R.
• Format: Journal Article
• Language: English
• Published: United States National Institute of Environmental Health Sciences. National Institutes of Health. Department of Health, Education and Welfare 01.07.1992; National Institute of Environmental Health Sciences
• Subjects: Alveolar macrophages; Animals; Bronchoalveolar lavage; Bronchoalveolar Lavage Fluid - enzymology; Cell membranes; Coal - adverse effects; Coal mining; Environmental Sciences; Enzymes; Guinea Pigs; Immune Response to Inhaled Particles; Life Sciences; Lungs; Lymphocytes; Macrophages; Macrophages, Alveolar - drug effects; Macrophages, Alveolar - enzymology; Macrophages, Alveolar - pathology; Male; Neuraminidase - metabolism; Neutrophils; Pneumoconiosis - enzymology; Pneumoconiosis - etiology; Pneumoconiosis - pathology; Prokaryotic cells; Toxicology
• ISSN: 0091-6765; 1552-9924
• DOI: 10.1289/ehp.9297103

The origin of immune dysfunctions that are observed in pneumoconiotic miners still remains unknown. There is evidence that the carbohydrate moiety of membrane glycoconjugates is of primary importance in many functions of immunocompetent cells. The glycosylation, and especially the sialylation level of membrane components of various lymphocyte and macrophage subsets, vary depending on the state of cellular differentiation and activation. Sialidases, which may regulate the amount of sialic acids exposed on the cell membrane, can thus be considered as immunoregulatory enzymes. In this report, the sialidase activity has been measured in alveolar macrophages (AM) and in cell-free bronchoalveolar lavage fluid (BALF) from guinea pigs exposed for 4 months to coal mine dust at a concentration of 300 mg/ m3. The samples were collected by bronchoalveolar lavage 2 months after cessation of exposure. The sialidase activity in the cell-free fluid and in the purified alveolar macrophages showed a 10-fold decrease (p < 0.001). Kinetic parameters of the enzyme such as Kmand optimum pH did not change. This changed activity was specific for sialidase, as two other lysosomal glycosidases, β-galactosidase and N-acetylglucosaminidase, showed unchanged activities. These results suggest the possibility that, by inducing a decreased sialidase activity, exposure to coal mine dust may lead to a modified expression of AM membrane-associated sialic acids giving rise to altered immune functions (i.e., phagocytosis, antigen processing, response to cytokines, etc.).