Cytotoxicity of fly-ash in alveolar macrophages from hypothyroid rats

Fly-ash particles of a diameter smaller than 2 mu were collected from the electrostatic precipitator of a coal-fired power plant, and their cytotoxicity was studied in culture using alveolar macrophages from healthy and hypothyroid rats. The mortality rate and the secretion rates of cytoplasmic (lactate dehydrogenase) and lysosomal (acid phosphatase and beta-glucuronidase) enzymes into the culture medium were greater in the alveolar macrophages from hypothyroid rats than in the control macrophages. Electron microscopy showed a retraction of filapodia, loss of ruffled membrane and distortion of cell shape in the alveolar macrophages from hypothyroid rats. These results demonstrate that the cytotoxicity of fly-ash particles was enhanced in the macrophages from hypothyroid rats, and indicate that the normal functions of alveolar macrophages are impaired by changes in thyroid status.