CD11b (EP45), RMab

Summary and Explanation

Integrin alpha M (ITGAM) is one protein subunit that forms the heterodimeric integerin alpha-M beta-2 molecule, also known as macrophage-1 antigen (Mac-1) or complement receptor 3 (CR3). ITGAM is also known as CR3A and cluster of differentiation molecule 11B (CD11b). The αMβ2 molecule is expressed on the surface of many leukocytes involved in the innate immune system, including monocytes, granulocytes, macrophages, and natural killer cells. It mediates inflammation by regulating luekocyte adhesion and migration and has been implicated in several immune processes such as phagocytosis, cell-mediated cytoxicity, chemotaxis and cellular activation. The ITGAM subunit of αMβ2 is directly involved in causing the adhesion and spreading of cells but cannot mediate cellular migration without the presence of the Beta-2 (CD18) subunit.

CD11b antibody has been used as a common myeloid marker and is expressed in about 50% of acute myeloid leukemia (AML). In combination with CD117, CD11b is helpful in differentiating acute promyelocytic leukemia (CD11b negative) from recovering benign myeloid proliferation (CD11b positive, CD117 negative).