Murine bone marrow cell line producing colony-stimulating factor.

A cell line (H-1) derived from the adherent layer of a 14-wk-old Dexter bone marrow culture has been maintained as cloned and uncloned lines through 21 passages at the time of these studies. These cell lines develop many fat droplets as they age and become confluent. The uncloned line produces increasing amounts of colony-stimulating activity as the cells become confluent. Feeder layers or supernatants from the nonconfluent or confluent fat-laden cells stimulate the formation of greater numbers of colonies derived from cultures of colony-forming units (CFU) than does medium from L cell culture containing colony-stimulating factor (CSF). Antibody to the CSF-containing medium from L cell culture neutralizes the colony-stimulating activity, thus showing immunologic similarity to a known molecular species that stimulates colony production in a CFU culture that produces granulocyte or macrophage populations, or both.