Integrin alpha M (ITGAM) is one protein subunit that forms the heterodimeric
integrinIntegrins are receptors that mediate attachment between a cell and the tissues surrounding it, which may be other cells or the extracellular matrix . They also play a role in cell signaling and thereby define cellular shape, mobility, and regulate the cell cycle.Typically, receptors inform a cell...
alpha-M beta-2 (α
Mβ
2) molecule, also known as
macrophage-1 antigen (
Mac-1MAC-1 may refer to:* Macrophage-1 antigen* Integrin alpha M...
) or
complement receptorA complement receptor is a receptor of the complement system, a part of the mediated innate immune system. Complement receptors are responsible for detecting pathogens by mechanisms not mediated by antibodies. Complement activity is not antigen sensitive, but can be triggered by specific antigens...
3 (CR3). ITGAM is also known as CR3A, and
cluster of differentiationThe cluster of differentiation is a protocol used for the identification and investigation of cell surface molecules present on White blood cells. CD molecules can act in numerous ways, often acting as receptors or ligands important to the cell...
molecule 11B (CD11B). The second chain of α
Mβ
2 is the common integrin β
2 subunit known as
CD18Integrin beta-2 is a protein that in humans is encoded by the ITGB2 gene.CD18 is the beta subunit of three different structures:* LFA-1 * Macrophage-1 antigen * Integrin alphaXbeta2...
, and integrin α
Mβ
2 thus belongs to the β
2 subfamily (or leukocyte) integrins.
α
Mβ
2 is expressed on the surface of many leukocytes involved in the
innate immune systemThe innate immune system comprises the cells and mechanisms that defend the host from infection by other organisms, in a non-specific manner. This means that the cells of the innate system recognize and respond to pathogens in a generic way, but unlike the adaptive immune system, it does not confer...
, including
monocyteMonocyte is a type of white blood cell, part of the human body's immune system. Monocytes have two main functions in the immune system: replenish resident macrophages and dendritic cells under normal states, and in response to inflammation signals, monocytes can move quickly Monocyte is a type of...
s,
granulocyteGranulocytes are a category of white blood cells characterised by the presence of granules in their cytoplasm. They are also called polymorphonuclear leukocytes because of the varying shapes of the nucleus, which is usually lobed into three segments...
s,
macrophageMacrophages are white blood cells within tissues, produced by the division of monocytes. Human macrophages are about in diameter...
s, and
natural killer cellNatural killer cells are a type of cytotoxic lymphocyte that constitute a major component of the innate immune system. NK cells play a major role in the rejection of tumors and cells infected by viruses...
s.
Integrin alpha M (ITGAM) is one protein subunit that forms the heterodimeric
integrinIntegrins are receptors that mediate attachment between a cell and the tissues surrounding it, which may be other cells or the extracellular matrix . They also play a role in cell signaling and thereby define cellular shape, mobility, and regulate the cell cycle.Typically, receptors inform a cell...
alpha-M beta-2 (α
Mβ
2) molecule, also known as
macrophage-1 antigen (
Mac-1MAC-1 may refer to:* Macrophage-1 antigen* Integrin alpha M...
) or
complement receptorA complement receptor is a receptor of the complement system, a part of the mediated innate immune system. Complement receptors are responsible for detecting pathogens by mechanisms not mediated by antibodies. Complement activity is not antigen sensitive, but can be triggered by specific antigens...
3 (CR3). ITGAM is also known as CR3A, and
cluster of differentiationThe cluster of differentiation is a protocol used for the identification and investigation of cell surface molecules present on White blood cells. CD molecules can act in numerous ways, often acting as receptors or ligands important to the cell...
molecule 11B (CD11B). The second chain of α
Mβ
2 is the common integrin β
2 subunit known as
CD18Integrin beta-2 is a protein that in humans is encoded by the ITGB2 gene.CD18 is the beta subunit of three different structures:* LFA-1 * Macrophage-1 antigen * Integrin alphaXbeta2...
, and integrin α
Mβ
2 thus belongs to the β
2 subfamily (or leukocyte) integrins.
α
Mβ
2 is expressed on the surface of many leukocytes involved in the
innate immune systemThe innate immune system comprises the cells and mechanisms that defend the host from infection by other organisms, in a non-specific manner. This means that the cells of the innate system recognize and respond to pathogens in a generic way, but unlike the adaptive immune system, it does not confer...
, including
monocyteMonocyte is a type of white blood cell, part of the human body's immune system. Monocytes have two main functions in the immune system: replenish resident macrophages and dendritic cells under normal states, and in response to inflammation signals, monocytes can move quickly Monocyte is a type of...
s,
granulocyteGranulocytes are a category of white blood cells characterised by the presence of granules in their cytoplasm. They are also called polymorphonuclear leukocytes because of the varying shapes of the nucleus, which is usually lobed into three segments...
s,
macrophageMacrophages are white blood cells within tissues, produced by the division of monocytes. Human macrophages are about in diameter...
s, and
natural killer cellNatural killer cells are a type of cytotoxic lymphocyte that constitute a major component of the innate immune system. NK cells play a major role in the rejection of tumors and cells infected by viruses...
s. It mediates inflammation by regulating leukocyte
adhesionCellular adhesion is the binding of a cell to a surface, extracellular matrix or another cell using cell adhesion molecules such as selectins, integrins, and cadherins.- Process :...
and migration and has been implicated in several immune processes such as
phagocytosisPhagocytosis is the cellular process of phagocytes and protists of engulfing solid particles by the cell membrane to form an internal phagosome...
, cell-mediated cytotoxicity,
chemotaxisChemotaxis is the phenomenon in which bodily cells, bacteria, and other single-cell or multicellular organisms direct their movements according to certain chemicals in their environment. This is important for bacteria to find food by swimming towards the highest concentration of food molecules, or...
and cellular activation. It is involved in the
complement systemThe complement system is a biochemical cascade that helps clear pathogens from an organism. It is part of the larger immune system that is not adaptable and does not change over the course of an individual's lifetime; as such it belongs to the innate immune system...
due to its capacity to bind inactivated complement component 3b (iC3b). The ITGAM (alpha) subunit of integrin α
Mβ
2 is directly involved in causing the adhesion and spreading of cells but cannot mediate cellular migration without the presence of the β2 (CD18) subunit.
In genomewide association studies, single nucleotide polymorphisms in ITGAM had the strongest association with
systemic lupus erythematosusSystemic lupus erythematosus is a chronic autoimmune connective tissue disease that can affect any part of the body...
, with an odds ratio of 1.65 for the T allele of rs9888739 and lupus.
Further reading
External links