Modulation of peripheral lymphocyte and alveolar macrophage activity by magnesite emissions

Modulation of alveolar macrophage and peripheral lymphocyte activities in rats exposed to magnesite emissions was tested under field and laboratory conditions. The field exposure test were conducted in a locality near a magnesite ore processing plant, the time observation was 18 weeks. The laboratory exposure tests were performed in an inhalation chamber at a constant magnesite dust aerosol concentration of 50 mg . m-3; the animals were exposed 4 hours a day, 5 days a week for a period of 70 days. Eighteen weeks of exposure to magnesium-polluted ambient air was found to increase the number of alveolar macrophages, to stimulate acid phosphatase activity in these cells, and to enhance activity of peripheral B lymphocytes to form EAC rosettes. The inhalation chamber experiments, evaluated after 46 and 70 days of exposure, resulted in an enhanced acid phosphatase activity of alveolar macrophages, enhanced lactate dehydrogenase activity of peripheral lymphocytes and in an increased percentage of B lymphocytes in blood, depending on exposure time. The activation of peripheral lymphocytes and alveolar macrophages observed in rats exposed under field and laboratory (here in dependence on exposure time) conditions clearly suggest that the cells participating in the induction and expression of the immune response are distinctly modulated in their activity by in vivo exposure to magnesite dust.