EFFECT OF SILICA ON A CULTURE OF RAT PERITONEAL-MACROPHAGES

Non-elicited rat peritoneal macrophages were cultured for 1-6 days with and without silica. The decrease in DNA, RNA and protein of the cells was accelerated by silica. However, the silica-treated cells contained nucleic acids of high molecular weight which were liberated to the culture medium as distinct molecules. Initially the silica-treated cells released lactate dehydrogenase, ATPase and alkaline RNase to the culture medium more rapidly than control cells. Thioglycollate-elicited macrophages contained higher amounts of polysomal RNA than native cells and did not liberate alkaline RNase into the culture medium. Media from 0-4 day macrophage cultures inhibited, in part, protein and DNA synthesis of cultured granulation-tissue fibroblasts. Culture media from silica-treated macrophages had a lower inhibitory effect and the 4-6 day medium even slightly stimulated the protein synthesis. The sil ica treatment thus alters the proportions of the stimulatory and inhibitory factors liberated from the macrophages. © 1979 British Occupational Hygiene Society.