Colony-stimulating factors (CSFs) are secreted

glycoprotein Glycoproteins are proteins which contain oligosaccharide (sugar) chains covalently attached to amino acid side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known a ...

s that bind to receptor proteins on the surfaces of committed progenitors in the bone marrow, thereby activating

intracellular signaling In biology, cell signaling (cell signalling in British English) is the Biological process, process by which a Cell (biology), cell interacts with itself, other cells, and the environment. Cell signaling is a fundamental property of all Cell (biol ...

pathways that can cause the cells to proliferate and differentiate into a specific kind of

blood cell A blood cell (also called a hematopoietic cell, hemocyte, or hematocyte) is a cell produced through hematopoiesis and found mainly in the blood. Major types of blood cells include red blood cells (erythrocytes), white blood cells (leukocytes), ...

(usually

white blood cells White blood cells (scientific name leukocytes), also called immune cells or immunocytes, are cells of the immune system that are involved in protecting the body against both infectious disease and foreign entities. White blood cells are genera ...

. For red blood cell formation, see

erythropoietin Erythropoietin (; EPO), also known as erythropoetin, haematopoietin, or haemopoietin, is a glycoprotein cytokine secreted mainly by the kidneys in response to cellular hypoxia; it stimulates red blood cell production ( erythropoiesis) in th ...

). They may be synthesized and administered exogenously. However, such molecules can at a latter stage be detected, since they differ slightly from the endogenous ones in, e.g., features of

post-translational modification In molecular biology, post-translational modification (PTM) is the covalent process of changing proteins following protein biosynthesis. PTMs may involve enzymes or occur spontaneously. Proteins are created by ribosomes, which translation (biolog ...

Etymology

The name "colony-stimulating factors" comes from the method by which they were discovered. Hematopoietic stem cells were cultured (see

cell culture Cell culture or tissue culture is the process by which cell (biology), cells are grown under controlled conditions, generally outside of their natural environment. After cells of interest have been Cell isolation, isolated from living tissue, ...

) on a so-called semisolid matrix, which prevents cells from moving around, so that, if a single cell starts proliferating, all of the cells derived from it will remain clustered around the spot in the matrix where the first cell was originally located. These are referred to as "colonies". Therefore, it was possible to add various substances to cultures of hemopoietic stem cells and then examine which kinds of colonies (if any) were "stimulated" by them. The substance that was found to stimulate formation of colonies of

macrophages Macrophages (; abbreviated MPhi, φ, MΦ or MP) are a type of white blood cell of the innate immune system that engulf and digest pathogens, such as cancer cells, microbes, cellular debris and foreign substances, which do not have proteins that ...

, for instance, was called

macrophage colony-stimulating factor The colony stimulating factor 1 (CSF1), also known as macrophage colony-stimulating factor (M-CSF), is a secreted cytokine which causes hematopoietic stem cells to differentiate into macrophages or other related cell types. Eukaryotic cells also ...

, for granulocytes, granulocyte colony-stimulating factor, and so on.

Mechanism

The colony-stimulating factors are soluble (permeable), in contrast to other, membrane-bound substances of the hematopoietic microenvironment. This is sometimes used as the definition of CSFs. They transduce by

paracrine In cellular biology, paracrine signaling is a form of cell signaling, a type of cellular communication (biology), cellular communication in which a Cell (biology), cell produces a signal to induce changes in nearby cells, altering the behaviour of ...

endocrine The endocrine system is a messenger system in an organism comprising feedback loops of hormones that are released by internal glands directly into the circulatory system and that target and regulate distant organs. In vertebrates, the hypotha ...

, or

autocrine Autocrine signaling is a form of cell signaling in which a cell secretes a hormone or chemical messenger (called the autocrine agent) that binds to autocrine receptors on that same cell, leading to changes in the cell. This can be contrasted with ...

signaling.

Examples

Colony-stimulating factors include: * –

* –

Granulocyte macrophage colony-stimulating factor Granulocytes are cells in the innate immune system characterized by the presence of specific granules in their cytoplasm. Such granules distinguish them from the various agranulocytes. All myeloblastic granulocytes are polymorphonuclear, that is ...

s (also called GM-CSF and sargramostim) * –

Granulocyte colony-stimulating factor Granulocyte colony-stimulating factor (G-CSF or GCSF), also known as colony-stimulating factor 3 (CSF 3), is a glycoprotein that stimulates the bone marrow to produce granulocytes and stem cells and release them into the bloodstream. Function ...

s (also called G-CSF and

filgrastim Filgrastim, sold under the brand name Neupogen among others, is a medication used to treat low neutrophil count. Low neutrophil counts may occur with HIV/AIDS, following chemotherapy or radiation poisoning, or be of an unknown cause. It may ...

) *

Interleukin 3 Interleukin 3 (IL-3) is a protein that in humans is encoded by the ''IL3'' gene localized on chromosome 5q31.1. Sometimes also called colony-stimulating factor, multi-CSF, mast cell growth factor, MULTI-CSF, MCGF; MGC79398, MGC79399: after remo ...

* Synthetic – Promegapoietin

Clinical uses

* Bone marrow stimulation * Stem cell mobilization

References

External links

* Cytokines {{protein-stub