Indoleamine 2,3-dioxygenase
Encyclopedia
Indoleamine-pyrrole 2,3-dioxygenase (IDO or INDO EC 1.13.11.52) is an immunomodulator
y enzyme produced by some alternatively activated macrophage
s and other immunoregulatory cells (also used as an immune subversion strategy by many tumors). In humans, IDO is encoded by the INDO gene
.
Interferon-gamma
has an antiproliferative effect on many tumor cells and inhibits intracellular pathogens such as Toxoplasma
and chlamydia
, at least partly because of the induction of indoleamine 2,3-dioxygenase. This enzyme catalyzes the degradation of the essential amino acid L-tryptophan to N-formylkynurenine.
IDO is the first and rate-limiting enzyme of tryptophan
catabolism
through kynurenine
pathway, thus causing depletion of tryptophan which can cause halted growth of microbes as well as T cell
s.
Immunomodulator
An immunomodulator, also known as an immunotherapy is a substance which has an effect on the immune system.- Immunosuppressants :Inhibits immune response in organ transplantation and autoimmune diseases.- Immunostimulants :...
y enzyme produced by some alternatively activated macrophage
Macrophage
Macrophages are cells produced by the differentiation of monocytes in tissues. Human macrophages are about in diameter. Monocytes and macrophages are phagocytes. Macrophages function in both non-specific defense as well as help initiate specific defense mechanisms of vertebrate animals...
s and other immunoregulatory cells (also used as an immune subversion strategy by many tumors). In humans, IDO is encoded by the INDO gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
.
Interferon-gamma
Interferon-gamma
Interferon-gamma is a dimerized soluble cytokine that is the only member of the type II class of interferons. This interferon was originally called macrophage-activating factor, a term now used to describe a larger family of proteins to which IFN-γ belongs...
has an antiproliferative effect on many tumor cells and inhibits intracellular pathogens such as Toxoplasma
Toxoplasma gondii
Toxoplasma gondii is a species of parasitic protozoa in the genus Toxoplasma. The definitive host of T. gondii is the cat, but the parasite can be carried by many warm-blooded animals . Toxoplasmosis, the disease of which T...
and chlamydia
Chlamydia (bacterium)
Chlamydia is a genus of bacteria that are obligate intracellular parasites. Chlamydia infections are the most common bacterial sexually transmitted infections in humans and are the leading cause of infectious blindness worldwide....
, at least partly because of the induction of indoleamine 2,3-dioxygenase. This enzyme catalyzes the degradation of the essential amino acid L-tryptophan to N-formylkynurenine.
IDO is the first and rate-limiting enzyme of tryptophan
Tryptophan
Tryptophan is one of the 20 standard amino acids, as well as an essential amino acid in the human diet. It is encoded in the standard genetic code as the codon UGG...
catabolism
Catabolism
Catabolism is the set of metabolic pathways that break down molecules into smaller units and release energy. In catabolism, large molecules such as polysaccharides, lipids, nucleic acids and proteins are broken down into smaller units such as monosaccharides, fatty acids, nucleotides, and amino...
through kynurenine
Kynurenine
L-Kynurenine is a metabolite of the amino acid L-tryptophan used in the production of niacin. It has been associated with tics.Kynureninase catabolizes the conversion of kynurenine into anthranilic acid while kynurenine-oxoglutarate transaminase catabolizes its conversion into kynurenic acid...
pathway, thus causing depletion of tryptophan which can cause halted growth of microbes as well as T cell
T cell
T cells or T lymphocytes belong to a group of white blood cells known as lymphocytes, and play a central role in cell-mediated immunity. They can be distinguished from other lymphocytes, such as B cells and natural killer cells , by the presence of a T cell receptor on the cell surface. They are...
s.