Growth of ovine granulocyte-macrophage precursors in vitro without exogenous colony-stimulating activity

Ovine granulocyte-macrophage colony-forming units (CFU-GM) from peripheral blood and bone marrow were cultured in vitro. The colony-stimulating activity (CSA) was provided by various conditioned-media previously reported to contain CSA and by homologous sheep serum (SS). The maximum number of CFU-GM was observed in the cultures containing SS without the addition of exogenous CSA. The CFU-GM appeared earlier in the cultures containing bone marrow cells when compared to the peripheral blood CFU-GM. Replacement of SS by bovine fetal serum resulted in suboptimal growth of ovine CFU-GM.