Four distinct colony-stimulating factors (CSFs) promoting survival, proliferation and differentiation of bone marrow precursor cells have been well characterized: granulocyte-macrophage-CSF (GM-CSF), granulocyte-CSF (G-CSF), macrophage-CSF (M-CSF), and interleukin-3 (IL-3, Multi-CSF). GM-CSF is a multipotential growth factor, stimulating proliferation of progenitor cells from more than one hematopoietic lineage (granulocyte, macrophage, and eosinophil). GM-CSF stimulates colony formation from pluripotent progenitor cells at extremely low concentrations and is an essential survival and proliferative factor for hematopoietic progenitor cells in all divisions up to maturity. GM-CSF induces myeloid progenitor cells from bone marrow to form colonies containing macrophages and granulocytes in a semisolid media. It is produced by various cell types (activated T cells, B cells, macrophages, mast cells, endothelial cells, and fibroblasts) in response to cytokine and inflammatory stimuli. In addition to granulocyte-macrophage progenitors, GMCSF is a growth factor for erythroid, megakaryocyte, and eosinophil progenitors. GM-CSF can induce nonhematopoietic cells such as endothelial cells to migrate and proliferate. It also stimulates the proliferation of tumor cell lines, including osteogenic sarcoma, carcinoma, and adenocarcinoma cell lines. GM-CSF exerts its biological effects through binding to specific cell surface receptors. The high affinity GM-CSF receptors contain a GM-CSF-specific α?chain and a common α ?chain.
Recombinant Rat Granulocyte-Macrophage Colony Stimulating Factor (GM-CSF) is produced from a DNA sequence encoding mature rat GM-CSF. This recombinant protein is a mixture of two rat GM-CSFs, the 127 amino acid form and the 128 amino acid methionyl form. Mature rat GM-CSF has a calculated mass of 14.7 kDa. GM-CSF, an acidic glycoprotein, is species-specific.