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.
