GMCSF

GM-CSF, or granulocyte-macrophage colony-stimulating factor, is a cytokine that acts as a hematopoietic growth factor for myeloid cells. It is produced by various cells, including T cells, macrophages, endothelial cells, and fibroblasts, in response to immune stimuli. The GM-CSF receptor is a heterodimer consisting of an alpha subunit that binds GM-CSF and a beta common subunit that transduces signals. Binding activates intracellular pathways such as JAK-STAT, MAPK, and PI3K, promoting survival, proliferation, and differentiation of bone marrow progenitors into granulocytes (neutrophils, eosinophils, basophils) and macrophages, and enhancing functions of mature cells. GM-CSF also promotes antigen presentation and macrophage/dendritic cell activation, supporting innate and adaptive immune responses.

Clinical use and administration: recombinant human GM-CSF is available as GM-CSF for therapeutic purposes and is marketed under names such as sargramostim (brand Leukine in some markets). It is approved to reduce chemotherapy-induced neutropenia, to mobilize hematopoietic progenitor cells for transplantation, and to accelerate engraftment after stem cell transplantation. It may be used to support immune responses in certain infections or vaccines and in some hematologic disorders, though its use varies by indication and region. GM-CSF differs from G-CSF in that it stimulates multiple myeloid lineages, not just neutrophils, and thus has a broader activity profile and side-effect spectrum.

Safety and considerations: common adverse effects include bone pain, fever, injection-site reactions, edema, and leukocytosis. Less frequently, capillary leak syndrome, pulmonary edema, or eosinophilia can occur. GM-CSF is generally avoided in active myeloid malignancies and requires careful monitoring for excessive myeloid activation in susceptible patients.