Effect of methimazole-induced hypothyroidism on alveolar macrophages.

Chemically induced hypothyroidism changes the functions of rat alveolar macrophages. Treatment of female rats with an anti-thyroid drug, methimazole (1% aqueous solution in drinking water for 6 weeks) significantly (p less than 0.05) reduced the ability of alveolar macrophages (MAM) to phagocytose and kill the yeast, Saccharomyces cerevisiae. Undigested yeasts were observed in phagolysosomes within MAM using transmission electron microscopy. The activities of the lysosomal enzymes, acid phosphatase and beta-glucuronidase, and the Fc receptor binding ability for immunoglobulin G, were lowered in MAM when compared with control macrophages (CAM). MAM also produced less tumor necrosis factor under the stimulation of lipopolysaccharide.