CSF

About Colony-stimulating factors:

Colony-stimulating factors are glycoproteins and part of the cytokine family, secreted throughout the human body. There are a variety of colony-stimulating factors, each of them playing a role in the production of bloods cells. Unlike erythropoietin, they specialize primarily in the production of white blood cells, including granulocytes like neutrophils. This is primarily done in response to infection within the body. Beyond their natural occurrence within the body, they are often synthesized and administered exogenously. When they are used in this way, they stimulate the stem cells in the bone marrow. This produces more of the particular white blood cells targeted by the specific colony stimulating factor. The new white blood cells then move into the blood and fight the infection. There are three different colony-stimulating factors, known as CSF1, CSF2, and CSF3 or MCSF, GM-CSF, and G-CSF respectively. Though they produce and interact with different white blood cells in different ways, they are closely tied to the process of the immune system.

Function
As mentioned, colony-stimulating factors are cytokines. They work by activated intracellular (cell-to-cell) signaling pathways. This causes the targeted cells to proliferate and differentiate into specific kinds of cells. As mentioned, the specific kinds of cells resulting from this tend to be white blood cells. They circulate through the blood, acting as hormones, but are also secreted locally in different parts of the body. Where it is secreted depends on which kind of colony-stimulating factor it is. There are three colony-stimulating factors known at present, CSF1, CSF 2 and CSF 3.

Mechanism and interactions
The mechanisms of the different colony-stimulating factors depend on which of them is secreted.

CSF1, also known as MCSF, influences hematopoietic stem cells, which give rise to all other kinds of blood cells through hematopoiesis. It causes them to differentiate into macrophages or related cell types. Furthermore, MCSF plays a key role in the survival, proliferation, and differentiation of mononuclear phagocytes and regulates cells of the female reproductive tract.

CSF2, also known as GM-CSF, controls the production, differentiation, and function of granulocytes (white blood cells with secretory granules) and macrophages (white blood cells that engulf and destroy anything lacking healthy proteins). GM-CSF is found in joints with rheumatoid arthritis. Blocking GM-CSF may reduce the inflammation or damage but it’s also used as a medication to improve white cell production after chemotherapy and as a vaccine adjuvant in cases of HIV infection.

CSF3, also known as G-CSF, stimulates the bone marrow to generate granulocytes and stem cells, then releasing them into the blood stream. It also plays a key role in the survival, proliferation, differentiation, and function of neutrophil precursors and mature neutrophils, which are immune cells with granules containing enzymes that are released during infections, allergic reactions, and bouts of asthma.

Structure
The three different colony-stimulating factors also share different structures, though they have similarities. All active forms of the cytokines of this type are found extracellularly as a disulfide-linked homodimer. They are produced by different methods as far as we known, with CSF1 thought to be produced by proteolytic cleavage of membrane-bound precursors