page_title: Phagocyte
section_title: Role in apoptosis
hierarchical_section_title: Phagocyte / Role in apoptosis
caption_attribution_description: Labelled diagram of a cell undergoing apoptosis. File adapted from a German Wikipedia entry: http://de.wikipedia.org/wiki/Bild:Apoptose-german.png
context_page_description: Phagocytes are cells that protect the body by ingesting harmful foreign particles, bacteria, and dead or dying cells. Their name comes from the Greek phagein, "to eat" or "devour", and "-cyte", the suffix in biology denoting "cell", from the Greek kutos, "hollow vessel". They are essential for fighting infections and for subsequent immunity. Phagocytes are important throughout the animal kingdom and are highly developed within vertebrates. One litre of human blood contains about six billion phagocytes. They were discovered in 1882 by Ilya Ilyich Mechnikov while he was studying starfish larvae. Mechnikov was awarded the 1908 Nobel Prize in Physiology or Medicine for his discovery. Phagocytes occur in many species; some amoebae behave like macrophage phagocytes, which suggests that phagocytes appeared early in the evolution of life.
  Phagocytes of humans and other animals are called "professional" or "non-professional" depending on how effective they are at phagocytosis. The professional phagocytes include many types of white blood cells.
context_section_description: In an animal, cells are constantly dying. A balance between cell division and cell death keeps the number of cells relatively constant in adults. There are two different ways a cell can die: by necrosis or by apoptosis. In contrast to necrosis, which often results from disease or trauma, apoptosis—or programmed cell death—is a normal healthy function of cells. The body has to rid itself of millions of dead or dying cells every day, and phagocytes play a crucial role in this process.
  Dying cells that undergo the final stages of apoptosis display  molecules, such as phosphatidylserine, on their cell surface to attract phagocytes. Phosphatidylserine is normally found on the cytosolic surface of the plasma membrane, but is redistributed during apoptosis to the extracellular surface by a  protein known as scramblase. These molecules mark the cell for phagocytosis by cells that possess the appropriate receptors, such as macrophages. The removal of dying cells by phagocytes occurs in an orderly manner without eliciting an inflammatory response and is an important function of phagocytes.
caption: Apoptosis—phagocytes clear fragments of dead cells from the body
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