588 COLONY-FORMATING-CELL IN BONE MARROW AND PERITONEAL EXUDATE OF ISOGENIC CHIMERAS

Abstract

Mouse peritoneal or pleural exudate induced by injection of various stimulants contain cells that are capable of clonal growth of macrophage colonies in vitro. However, cells obtained from unstimulated peritoneal or pleural cavities had none or very few such colony-forming cells (CFC). These peritoneal exudate CFC differ from that of bone marrow CFC by having a longer period before proliferation and producing only macrophage colonies. AKR mice were given a lethal dose of total body radiation (900 rads) and then received intravenously 5×106 nucleated marrow cells from unirradiated mice. Peritoneal exudate was induced by injection of 1.5 ml thioglycollate medium 3 days before collection of exudate. Repopulation of CFC from both bone marrow and peritoneal exudate was then assayed. Exponential growth of CFC in bone marrow was noted between 3-10 days and ther reached gradually to unirradiated levels in 5 weeks. The growth curve of these marrow CFC measured by this in vitro culture method is similar to that of CFC assayed by the in vivo spleen colony method. However, no measurable CFC in peritoneal exudate was noted in the first 7 days. The growth curve of peritoneal CFC is similar to that of marrow CFC after 2 weeks. A close relationship of CFC between bone marrow and peritoneal exudate seems to exist. However, the origin of these peritoneal exudate CFC either as “activated” peritoneal cells or migrated cells from bone marrow is still unclear.