Phagocyte

phagocytesphagocytic cellsphagocyticphagocytic cellphagocytosedPhagocytosismononuclear phagocytesnonphagocytic cellsphagocytisingphagocytize
Phagocytes are cells that protect the body by ingesting harmful foreign particles, bacteria, and dead or dying cells.wikipedia
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Élie Metchnikoff

Ilya Ilyich MechnikovIlya MechnikovElie Metchnikoff
They were discovered in 1882 by Ilya Ilyich Mechnikov while he was studying starfish larvae.
In particular, he is credited with the discovery of phagocytes (macrophages) in 1882.

Apoptosis

apoptoticprogrammed cell deathcell death
Phagocytes are cells that protect the body by ingesting harmful foreign particles, bacteria, and dead or dying cells.
Unlike necrosis, apoptosis produces cell fragments called apoptotic bodies that phagocytic cells are able to engulf and remove before the contents of the cell can spill out onto surrounding cells and cause damage to them.

Phagosome

phagosomesphagocytic vacuolephagosomal
Once inside this phagocyte, the bacterium is trapped in a compartment called a phagosome.
In cell biology, a phagosome is a vesicle formed around a particle engulfed by a phagocyte via phagocytosis.

Complement system

complementcomplement cascadecomplement activation
Opsonin receptors increase the phagocytosis of bacteria that have been coated with immunoglobulin G (IgG) antibodies or with complement.
The end result of this complement activation or complement fixation cascade is stimulation of phagocytes to clear foreign and damaged material, inflammation to attract additional phagocytes, and activation of the cell-killing membrane attack complex.

Starfish

Asteroideasea starsea stars
They were discovered in 1882 by Ilya Ilyich Mechnikov while he was studying starfish larvae.
The body fluid contains phagocytic cells called coelomocytes, which are also found within the hemal and water vascular systems.

Necrosis

necroticnecrotizingnecrotic tissue
There are two different ways a cell can die: by necrosis or by apoptosis.
This initiates in the surrounding tissue an inflammatory response which attracts leukocytes and nearby phagocytes which eliminate the dead cells by phagocytosis.

Respiratory burst

oxidative burstneutrophil respiratory burst(oxidative burst)
The increase in oxygen consumption, called a respiratory burst, produces reactive oxygen-containing molecules that are anti-microbial.
It is a crucial reaction that occurs in phagocytes to degrade internalized particles and bacteria.

Macrophage

macrophagesM2 macrophagesTissue macrophages
The professional phagocytes include many types of white blood cells (such as neutrophils, monocytes, macrophages, mast cells, and dendritic cells).
These large phagocytes are found in essentially all tissues, where they patrol for potential pathogens by amoeboid movement.

Superoxide

superoxide anionsuperoxide radicalsuperoxides
The first type is the oxygen-dependent production of a superoxide, which is an oxygen-rich bacteria-killing substance.
In phagocytes, superoxide is produced in large quantities by the enzyme NADPH oxidase for use in oxygen-dependent killing mechanisms of invading pathogens.

Antibody

antibodiesimmunoglobulinimmunoglobulins
Opsonin receptors increase the phagocytosis of bacteria that have been coated with immunoglobulin G (IgG) antibodies or with complement. In 1903, Almroth Wright discovered that phagocytosis was reinforced by specific antibodies that he called opsonins, from the Greek opson, "a dressing or relish".
First, the binding of the antibody and complement molecules marks the microbe for ingestion by phagocytes in a process called opsonization; these phagocytes are attracted by certain complement molecules generated in the complement cascade.

Neutrophil

neutrophilsneutrophil granulocyteneutrophilic
The professional phagocytes include many types of white blood cells (such as neutrophils, monocytes, macrophages, mast cells, and dendritic cells).
Neutrophils are a type of phagocyte and are normally found in the bloodstream.

T helper cell

Th1Th2T helper cells
The source of interferon-gamma can be CD4 + T cells, CD8 + T cells, natural killer cells, B cells, natural killer T cells, monocytes, macrophages, or dendritic cells.
They are essential in B cell antibody class switching, in the activation and growth of cytotoxic T cells, and in maximizing bactericidal activity of phagocytes such as macrophages.

Granulocyte

granulocytesgranulocytopeniapolymorphonuclear leukocyte
They derive from monocytes, granulocyte stem cells, or the cell division of pre-existing macrophages.
Neutrophils are normally found in the bloodstream and are the most abundant type of phagocyte, constituting 60% to 65% of the total circulating white blood cells, and consisting of two subpopulations: neutrophil-killers and neutrophil-cagers.

Inflammation

inflammatoryinflammatory responseinflamed
Binding to Toll-like receptors increases phagocytosis and causes the phagocyte to release a group of hormones that cause inflammation.
Some act as phagocytes, ingesting bacteria, viruses, and cellular debris.

Carl Friedrich Wilhelm Claus

ClausCarl ClausCarl Friedrich Claus
Mechnikov traveled to Vienna and shared his ideas with Carl Friedrich Claus who suggested the name "phagocyte" (from the Greek words phagein, meaning "to eat or devour", and kutos, meaning "hollow vessel" ) for the cells that Mechnikov had observed.
During his research on cell biology he coined the word phagocyte.

Innate immune system

innate immunityinnateinnate immune response
Phagocytes form part of the innate immune system, which animals, including humans, are born with.
The innate leukocytes include: Natural killer cells, mast cells, eosinophils, basophils; and the phagocytic cells include macrophages, neutrophils, and dendritic cells, and function within the immune system by identifying and eliminating pathogens that might cause infection.

Adaptive immune system

adaptive immunityadaptive immune responseadaptive
On the other hand, the adaptive immune system of jawed vertebrates—the basis of acquired immunity—is highly specialized and can protect against almost any type of invader.
On resolution of the infection, most effector cells die and phagocytes clear them away—but a few of these cells remain as memory cells.

Chédiak–Higashi syndrome

Chédiak-Higashi syndromeChediak-Higashi syndromeChediak–Higashi syndrome
Other rare congenital abnormalities, such as Chédiak–Higashi syndrome, are also associated with defective killing of ingested microbes.
The disease is characterised by large lysosome vesicles in phagocytes (neutrophils), which thus have poor bactericidal function, leading to susceptibility to infections, abnormalities in nuclear structure of leukocytes, anemia, and hepatomegaly.

Pulmonary alveolus

alveolialveolarpulmonary alveoli
Macrophages are found throughout the body in almost all tissues and organs (e.g., microglial cells in the brain and alveolar macrophages in the lungs), where they silently lie in wait.
Two types are pneumocytes known as type I and type II cells found in the alveolar wall, and a large phagocytic cell known as an alveolar macrophage that moves about in the lumens of the alveoli, and in the connective tissue between them.

Hydrogen peroxide

H 2 O 2 H2O2HO
The superoxide is converted to hydrogen peroxide and singlet oxygen by an enzyme called superoxide dismutase.
Cells called phagocytes engulf pathogens and then use hydrogen peroxide to destroy them.

Interleukin-1 family

IL-1interleukin-1interleukin 1
Macrophages cause inflammation through the production of interleukin-1, interleukin-6, and TNF-alpha.
These cytokines increase the expression of adhesion factors on endothelial cells to enable transmigration (also called diapedesis) of immunocompetent cells, such as phagocytes, lymphocytes and others, to sites of infection.

Major histocompatibility complex

MHCmajor histocompatibility complex (MHC)HLA loci
These peptides are then bound to the cell's major histocompatibility complex (MHC) glycoproteins, which carry the peptides back to the phagocyte's surface where they can be "presented" to lymphocytes.

Wound healing

wound repairscabvulnerary
Treponema pallidum—the bacterium that causes syphilis—hides from phagocytes by coating its surface with fibronectin, which is produced naturally by the body and plays a crucial role in wound healing.
One of the macrophage's roles is to phagocytize other expended phagocytes, bacteria and damaged tissue, and they also debride damaged tissue by releasing proteases.

Liver

hepaticliver protein synthesislivers
In the liver, damage by neutrophils can contribute to dysfunction and injury in response to the release of endotoxins produced by bacteria, sepsis, trauma, alcoholic hepatitis, ischemia, and hypovolemic shock resulting from acute hemorrhage.
The liver sinusoids are lined with two types of cell, sinusoidal endothelial cells, and phagocytic Kupffer cells.

Monocyte

monocytesmonocyticmononuclear
The professional phagocytes include many types of white blood cells (such as neutrophils, monocytes, macrophages, mast cells, and dendritic cells).