Culture of macrophage cell lines from normal mouse bone marrow.

The use of semisolid medium for the culture and cloning of haematopoietic cells has helped our understanding of their proliferation and differentiation. It has been shown that mixed colonies of granulocytes and macrophages developed, in the presence of colony-stimulating factor (CSF), from their common precursor, granulocyte-macrophage colony-forming cells (GM-CFC). Attempts at recloning these colonies in semisolid medium suggested that granulocytes and macrophages were differentiated cells incapable of further proliferation. However, our studies on cultures of larger numbers of cells demonstrate that while this may be the case for granulocytes, macrophages seem to be capable of long-term proliferation.