granulocyte colony-stimulating factor
Meaning of granulocyte colony-stimulating factor: The body's own instruction to the bone marrow to step up production of the white cells that handle bacteria.
Definition of granulocyte colony-stimulating factor
Granulocyte colony-stimulating factor is a natural signaling protein that tells the bone marrow to make neutrophils, the white blood cells that deal with bacterial infection. It also pushes mature neutrophils out of the marrow into the bloodstream and keeps them alive longer once there. Manufactured copies of the protein, such as filgrastim, are given as medicines under their own names.
What does it do in the body?
Neutrophils are the most numerous white cell in the blood and the first to arrive at a bacterial infection. They live only a day or so, so the marrow must replace them constantly. This colony-stimulating factor is the signal that sets the pace. Levels rise sharply during infection, and the marrow responds by shortening the time each precursor cell takes to mature and by releasing its reserve pool early. The name comes from the laboratory work that found it: added to marrow cells in a dish, it made colonies of one cell type grow.
How does it differ from GM-CSF?
| G-CSF | GM-CSF | |
|---|---|---|
| Cells stimulated | Neutrophils mainly | Neutrophils, monocytes and eosinophils |
| Range of effect | Narrow | Broader |
| Typical tolerance | Bone aches, usually mild | More fever and aching |
The wider reach of granulocyte-macrophage colony-stimulating factor is not automatically an advantage, and the narrower agent is the one used most.
How are the manufactured versions used?
Two uses are established. The first is after chemotherapy, which suppresses the marrow and leaves a window when neutrophils are too few to hold off infection. Giving the growth factor shortens that window. The second is stem cell collection: several days of treatment coaxes blood-forming stem cells out of the marrow and into the circulating blood, where they can be filtered off for transplantation. It is also used in some inherited conditions in which the marrow makes too few neutrophils from the outset.
Filgrastim is one manufactured form; longer-acting versions carry a chemical tail that slows their clearance, so fewer injections are needed. Aching in the pelvis and lower back is the common complaint, reflecting a marrow working hard, and enlargement or rupture of the spleen is a recognized but uncommon problem.
Also known as
Used in a sentence
The regimen included granulocyte colony-stimulating factor support following each chemotherapy cycle.
Good to know
Filgrastim is a manufactured version of the protein rather than another name for it, and the natural factor and the medicines made from it are not interchangeable terms.
Word origin
Where “granulocyte colony-stimulating factor” comes from
Granulocyte joins the Latin granulum, a small grain, to the Greek kytos, meaning cell, describing the grains visible inside these white cells.