A number of studies have investigated the properties of murine macrophages grown from bone marrow or peritoneal precursors in short-term culture, i.e. less than two weeks (Table 1). A source of myeloid or macrophage colony-stimulating factor (CSF) is essential for this growth (Stanley et al. 1976). Thus, using a source of predominately macrophage CSF, Watson et al. (1974) showed that liquid cultures would yield approximately 106 marrow cells) in seven days, over 95% with macrophage properties of morphology, adherence, carbonyl iron phagocytosis, neutral red pinocytosis, binding of glutaraldehyde-treated and antibody-sensitized RBC, and lysis of the latter. Marrow-derived macrophages have been an ideal subject for studies on in vitro activation of tumor cytotoxicity, since it is very difficult to maintain animals in the constant or germ-free evironment required for harvesting unstimulated control macrophages (Meerpohl et al. 1976).
