Integrin alpha M

Integrin alpha M (ITGAM) is one protein subunit that forms the is_associated_with::heterodimeric is_associated_with::integrin alpha-M beta-2 (αMβ2) molecule, also known as is_associated_with::macrophage-1 antigen (Mac-1) or is_associated_with::complement receptor 3 (CR3). ITGAM is also known as CR3A, and is_associated_with::cluster of differentiation molecule 11B (CD11B). The second chain of αMβ2 is the common integrin β2 subunit known as is_associated_with::CD18, and integrin αMβ2 thus belongs to the β2 subfamily (or leukocyte) integrins.

αMβ2 is expressed on the surface of many is_associated_with::leukocytes involved in the is_associated_with::innate immune system, including is_associated_with::monocytes, is_associated_with::granulocytes, is_associated_with::macrophages, and is_associated_with::natural killer cells. It mediates inflammation by regulating leukocyte adhesion and migration and has been implicated in several immune processes such as is_associated_with::phagocytosis, cell-mediated cytotoxicity, is_associated_with::chemotaxis and cellular activation. It is involved in the is_associated_with::complement system due to its capacity to bind inactivated is_associated_with::complement component 3b (iC3b). The ITGAM (alpha) subunit of integrin αMβ2 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 is_associated_with::systemic lupus erythematosus, with an odds ratio of 1.65 for the T allele of rs9888739 and lupus.

In is_associated_with::histopathology, immunohistochemistry with antibodies against CD11B is frequently used to identify is_associated_with::macrophages and is_associated_with::microglia.