AN IN-VITRO METHOD FOR STUDYING NUCLEIC ACID METABOLISM IN MURINE PERITONEAL MACROPHAGES

Squares of highly polished, high grade stainless-steel, of uniform area, have been shown to provide acceptable surfaces for the maintenance of murine peritoneal macrophages in vitro. When a mixture of 3H-uridine and 3H-thymidine is added to media in which the cells are maintained, 3H-uridine is incorporated into cellular RNA but little or no 3H-DNA synthesis is found. The incorporation of 3H-uridine into RNA is linear for at least 80 min in macrophages maintained in medium without calf serum for various times up to 15 days. Deviations from linearity occur after 18 h of culture in medium containing 10% calf serum. The results suggest that calf serum either stimulates a very rapid turnover of 3H-RNA in macrophages or that export of 3H-RNA to the medium is taking place. Comparison of the results of 3H-RNA synthesis in macrophages in the presence of isologous mouse serum with the highly significant increase in 3H-RNA synthesis in macrophages maintained in homologous mouse serum as well as in calf serum, foetal calf serum and rat serum suggest that the results are not simply due to the feeding of the cells, but due to their not being isologous. The observations are discussed in the context of current concepts of the role of macrophages in antibody production. © 1969.