Zeta’s mouse monoclonal antibody recognizes CD11c (ITGAX), a protein of 145kDa. CD11c (ITGAX), a member of the leuko-integrin family, shares the same beta subunit with other members of the leukocyte adhesion molecule family, which includes CD11a (LFA-1), CD11b (MAC-1) and CD11d (ITGAD), but has a unique alpha chain. CD11c has been shown to play a role in phagocytosis, cell migration, and cytokine production by monocytes/macrophages as well as induction of T-cell proliferation by Langerhans cells. CD11c is expressed prominently on the plasma membranes of monocytes, tissue macrophages, NK cells, and most dendritic cells (DCs). A lower level of expression is also observed on neutrophils as a result of its high level of expression on most DCs. Zeta’s monoclonal antibody to CD11c may aid in identification of lesions with histiocytic origin and the antibody to CD11c may also be used as a marker for hairy cell leukemia in paraffin-embedded tissues.