C-X-C motif chemokine 10 (CXCL10) also known as Interferon gamma-induced protein 10 (IP-10) or small-inducible cytokine B10 is an 8.7 kDa protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 that in humans is encoded by the CXCL10 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...

. C-X-C motif chemokine 10 is a small cytokine

Cytokine

Cytokines are small cell-signaling protein molecules that are secreted by the glial cells of the nervous system and by numerous cells of the immune system and are a category of signaling molecules used extensively in intercellular communication...

 belonging to the CXC chemokine

Chemokine

Chemokines are a family of small cytokines, or proteins secreted by cells. Their name is derived from their ability to induce directed chemotaxis in nearby responsive cells; they are chemotactic cytokines...

 family.

Gene

The gene for CXCL10 is located on human chromosome 4 in a cluster among several other CXC chemokines.

Function

CXCL10 is secreted by several cell types in response to IFN-γ. These cell types include monocyte

Monocyte

Monocytes are a type of white blood cell and are part of the innate immune system of vertebrates including all mammals , birds, reptiles, and fish. Monocytes play multiple roles in immune function...

s, endothelial cells and fibroblast

Fibroblast

A fibroblast is a type of cell that synthesizes the extracellular matrix and collagen, the structural framework for animal tissues, and plays a critical role in wound healing...

s. CXCL10 has been attributed to several roles, such as chemoattraction for monocyte

Monocyte

Monocytes are a type of white blood cell and are part of the innate immune system of vertebrates including all mammals , birds, reptiles, and fish. Monocytes play multiple roles in immune function...

s/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, 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, NK cells, and dendritic cells, promotion of 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...

 adhesion to endothelial cells, antitumor activity, and inhibition of bone marrow

Bone marrow

Bone marrow is the flexible tissue found in the interior of bones. In humans, bone marrow in large bones produces new blood cells. On average, bone marrow constitutes 4% of the total body mass of humans; in adults weighing 65 kg , bone marrow accounts for approximately 2.6 kg...

 colony formation and angiogenesis

Angiogenesis

Angiogenesis is the physiological process involving the growth of new blood vessels from pre-existing vessels. Though there has been some debate over terminology, vasculogenesis is the term used for spontaneous blood-vessel formation, and intussusception is the term for the formation of new blood...

.

This chemokine elicits its effects by binding to the cell surface chemokine receptor

Chemokine receptor

Chemokine receptors are cytokine receptors found on the surface of certain cells, which interact with a type of cytokine called a chemokine. There have been 19 distinct chemokine receptors described in mammals...

 CXCR3

CXCR3

Chemokine receptor CXCR3 is a Gαi protein-coupled receptor in the CXC chemokine receptor family. Other names for CXCR3 are G protein-coupled receptor 9 and CD183...

.

Structure

The three-dimensional crystal structure of this chemokine has been determined under 3 different conditions to a resolution of up to 1.92 Å. The Protein Data Bank

Protein Data Bank

The Protein Data Bank is a repository for the 3-D structural data of large biological molecules, such as proteins and nucleic acids....

accession codes for the structures of CXCL10 are , , and .

Clinical significance

Baseline pre-treatment plasma levels of CXCL10 are elevated in patients chronically infected with hepatitis C virus (HCV) of genotypes 1 or 4 who do not achieve a sustained viral response (SVR) after completion of antiviral therapy. CXCL10 in plasma is mirrored by intrahepatic CXCL10 mRNA, and both strikingly predict the first days of elimination of HCV RNA (“first phase decline”) during interferon/ribavirin therapy for all HCV genotypes. This also applies for patients co-infected with HIV, where pre-treatment IP-10 levels below 150 pg/mL are predictive of a favorable response, and may thus be useful in encouraging these otherwise difficult-to-treat patients to initiate therapy.

Further reading