Granulocyte Macrophage

 Granulocyte-macrophage settlement animating component (GM-CSF) was first distinguished in mouse lung tissue-molded medium after lipopolysaccharide infusion into mice by its capacity to invigorate expansion of mouse bone marrow cells in vitro and create provinces of the two granulocytes and macrophages .Much has been learned about the hematopoietic promoting effect of this heavily glycosylated cytokine. GM-CSF stimulates multipotent progenitor cells depending on its concentration, the proliferation of macrophage progenitors at the lowest doses, followed by granulocyte, erythroid, eosinophil, megakaryocyte and multipotent progenitors . It also stimulates the differentiation of myeloid leukemic cells and controls eosinophil function in some instances. GM-CSF is encoded by a 2.5 kb mRNA comprising 4 exons. It is secreted as a monomeric 23 kDa glycosylated small protein. Mature murine GM-CSF has 124 residues and human has 127 residues; both are derived from a precursor containing a signal peptide . Murine and human GM-CSF share modest structural homology at the level of the nucleotide (70%) and amino acid (56%) sequences. There is no cross-species receptor binding or biological activity, however. GM-CSF is produced by various cell types including macrophages, mast cells, T cells, fibroblasts and endothelial cells , mostly in response to immune activation and cytokines that mediate inflammation. It is present in serum and most tissues, and is additionally found related to the extracellular matrix and as an integral membrane protein.