CD18 represents the common ß2 integrin subunit that associates non-covalently with the a/ß chains of CD11a, CD11b, and CD11c to form various integrin heterodimers. It is expressed strongly on lymphocytes and monocytes and weakly on granulocytes. CD18 mediates a variety of heterotypic and homotypic intercellular adhesion reactions and it regulates the ligand-binding activates of the various CD11/CD18 complexes. The monoclonal antibody C71/16 has not been reported to inhibit cell adhesion.