GM CSF is a cytokine that controls the production, differentiation, and function of granulocytes and macrophages. The active form of the protein is found extracellularly as a homodimer. This gene has been localized to a cluster of related genes at chromosome region 5q31, which is known to be associated with interstitial deletions in the 5q- syndrome and acute myelogenous leukemia. Other genes in the cluster include those encoding interleukins 4, 5, and 13. GM CSF stimulates the growth and differentiation of hematopoietic precursor cells from various lineages, including granulocytes, macrophages, eosinophils and erythrocytes.
Granulocyte Macrophage Colony Stimulating Factor (GM CSF) Human Recombinant produced in E. coli is a single, non-glycosylated, polypeptide chain containing 127 amino acids and having a molecular mass of 14477 Dalton. GM CSF is purified by proprietary chromatographic techniques. GM CSF was lyophilized after extensive dialysis against 2 mM sodium phosphate buffer pH= 7.4±0.1. Purity is greater than 98.0% as determined by RP-HPLC and by SDS-PAGE. The sequence of the first five N-terminal amino acids was determined and was found to be Ala-Pro-Ala-Arg-Ser. N-terminal methionine has been completely removed enzymatically. The ED50 as determined by the dose-dependent stimulation of the proliferation of human TF-1 cells (human erythroleukemic indicator cell line) is < 0.1 ng/ml, corresponding to a Specific Activity of 11.1×106 IU/mg. GM-CSF quantitation was carried out by two independent methods: 1) UV spectroscopy at 280 nm using the absorbency value of 0.963 as the extinction coefficient for a 0.1% (1mg/ml) solution. This value is calculated by the PC GEN computer analysis program of protein sequences (IntelliGenetics). 2) Analysis by RP-HPLC, using a standard solution of GM-CSF as a Reference Standard.