CD18

What is the Cellular Role of the CD11 Protein?

The CD11 protein is actually a heterodimer complex that consists of CD11b and CD18. CD11 is involved in numerous adhesion-related associations between cells such as monocytes, macrophages, natural killer (NK) cells, and granulocytes. CD11 also regulates the uptake of complement-coated particles within cells. It has also gained usage as a microglial marker for tissues derived from the nervous system.

The protein CD11b has been implicated in the various adhesion-related interactions of cells such as monocytes, macrophages, natural killer (NK) cells, and granulocytes. It is part of a heterodimer that consists of CD11b and CD18. It also modulates the uptake of complement-coated particles within the cell. It is commonly used as a microglial marker in tissues derived from the nervous system.

The beta-2 integrins, a family of four cell surface transmembrane glycoproteins expressed only on leukocytes, include CD11a/CD18, CD11b/CD18, CD11c/CD18, and CD11d/CD18. They consist of a common beta subunit (CD18) and homologous alpha subunits (CD11a-d) that bind noncovalently to form an alpha/beta heterodimer.

Microglia are the resident macrophages of the central nervous system, and the first line of immune defense. Pioneering antibody research in the 1990's identified the Integrin beta 2 protein (also called ITGB2, complement receptor 3, CR3, CD18, and Mac-1) as one of the key proteins in the recruitment of microglial cells. The ITGB2 subunit A is commonly called CD11b, and antibodies to this subunit are widely used as microglial markers.

What is CD11b?

CD11b is an integrin family member which pairs with CD18 to form the CR3 heterodimer. CD11b is expressed on the surface of many leukocytes including monocytes, neutrophils, natural killer cells, granulocytes and macrophages, as well as on 8% of spleen cells and 44% of bone marrow cells. Functionally, CD11b regulates leukocyte adhesion and migration to mediate the inflammatory response.