The 3.9 antibody reacts with human CD11c, also known as integrin alpha X. This 150 kDa cell surface glycoprotein is part of a family of integrin receptors that mediate adhesion between cells (cell-cell) and components of the extracellular matrix, e.g. fibrinogen (cell-matrix). In addition, integrins are active signaling receptors which recruit leukocytes to inflammatory sites and promote cell activation. Complete, functional integrin receptors consist of distinct combinations of integrin chains which are differentially expressed. Integrin alpha X (CD11c) assembles with Integrin beta-2 (CD18) into a receptor known as CR4 which can bind and induce signaling through ICAMs and VCAM-1 on endothelial cells and can also facilitate removal of iC3b bearing foreign cells.

The 3.9 antibody is widely used as a marker for CD11c expression on dendritic cells (DC), often in parallel with markers for CD11b, for identification of developmental stages and mature subsets of this cell type. CD11c is prominently expressed on tissue macrophages, and is also detected on activated neutrophils, granulocytes, some types of activated T cells and intestinal intraepithelial lymphocytes (IEL). The antibody is reported to be cross-reactive with Baboon, Chimpanzee, Cynomolgus and Rhesus CD11c.

Type: Primary
Antigen: ITGAX (integrin, alpha X (complement component 3 receptor 4 subunit))
Clonality: monoclonal
Clone: 3.9
Conjugation: FITC (Fluorescein)
Epitope:
Host: Mouse
Isotype: IgG1 Kappa
Reactivity: Human