Chowdhury, Badrul Alam (1988) Prevention of cadmium induced immunopathology by zinc in mice. Doctoral (PhD) thesis, Memorial University of Newfoundland.
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Cadmium is an ubiquitous toxic metal to which everyone is exposed at low levels. It is toxic to almost every organ system of the body including the immune system. In this study, the effects of a relatively low dose of cadmium on the immune system of mice and the effects of a moderately large dose of zinc on cadmium-induced immunopathology were studied. Six-week old C57BL/6 male mice were exposed to 50 ppm cadmium in drinking water for 3 weeks, and killed 0, 3 and 6 weeks after cessation of treatment. In some groups, 500 ppm zinc was added to the drinking water with or after cadmium treatment. The number of IgM and IgG antibody-forming cells in the spleen was higher in cadmium-treated mice as compared to non-treated controls at 0 week. Concurrent zinc administration prevented the enhancement of antibody-forming cell response. Proliferative response of spleen cells to the T cell mitogens phytohaemagglutinin and concanavalin A tended to be high in cadmium-treated mice and zinc administration after exposure to cadmium tended to lower it. The number of CD8⁺ cells in the spleen was lower and the ratio of CD4⁺ to CD8⁺ cells, reflecting the balance of immunoregulatory T lymphocytes, was higher in cadmium treated mice. Concurrent zinc administration prevented the alteration of T cell subsets. Suppressor cell activity tended to be low in cadmium treated mice. Natural-killer cell activity in the spleen was low in cadmium treated mice and concurrent zinc treatment prevented the suppression. B cell count in the spleen and antibody production by splenic lymphocytes on pokeweed mitogen stimulation was not altered by cadmium or zinc treatment. Cadmium and zinc treatment had no effect on liver, kidneys, spleen and thymus weights and lymphocyte content of spleen, thymus and peripheral blood. Use of immunofluorescence with anti-mouse IgG and complement C3 showed no evidence of autoimmune reaction in kidney sections. On electron microscopic examination, ultrastructural alterations were seen in proximal tubular epithelial cells of the cadmium treated mice. Mitochondria were increased in number and the cisternae were distorted, and inside several cells electron dense materials were seen. Liver and kidney cadmium concentrations were high in cadmium-treated mice as compared to non-treated controls. Tissue cadmium levels were lower in mice treated with both zinc and cadmium than in those treated with cadmium alone. The results suggest that a relatively low dose of cadmium exposure produces immune alterations in mice that can be prevented by a moderately large dose of zinc. -- INDEXING KEY WORDS: cadmium; zinc; cellular immunity
|Item Type:||Thesis (Doctoral (PhD))|
|Additional Information:||Bibliography: leaves 149-172.|
|Department(s):||Medicine, Faculty of|
|Library of Congress Subject Heading:||Cadmium--Physiological effect; Zinc--Physiological effect; Cellular immunity|
|Medical Subject Heading:||Cadmium; Immunity, Cellular; Zinc|
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