Effect of mica dust and choline on the lymph nodes of rats.

Male albino rats given choline alone by intraperitoneal injection (40 doses of 25 mg/5 days a week over a period of 10 weeks), developed atypical lymphadenopathy at the end of the experiment (330 days). In a second group, the intratracheal instillation of single dose of 25 mg of respirable mica provoked proliferation of reticular cells and macrophages in the tracheobronchial lymph nodes. However, in a third group, the combined action of choline and mica caused marked lymphadenopathy with abnormal cells. The role of choline, an essential component of cell membrane, in enhancing the reaction to mica in the lymph nodes, is discussed.