The CD11b (HI11b) antibody recognizes the 165-kDa integrin ?M-chain associated with CD18, the 95-kDa integrin(B)2, which form a heterodimer glycoprotein called CD11b/CD18 (Mac-1). Leukocytes e, Xenopus/Amphibian,press four CD11/CD18 integrins which include a common (B)2 subunit and distinctive ? chains. Besides CD11b/CD18, the other three integrins are known as CD11a/CD18, CD11c/CD18 and CD11d/CD18. E, Xenopus/Amphibian,pression of the CD11b subunit on the leukocyte cell surface requires the presence of the CD18 subunit. Patients who have mutated CD18 genes do not e, Xenopus/Amphibian,press cell membrane Mac-1 (or the other (B)2 integrins), a condition known as leukocyte adhesion deficiency 1 (LAD-1), in which patients have major problems with bacterial infections. Mac-1 is highly e, Xenopus/Amphibian,pressed on neutrophils and monocytes/macrophages, a subset of NK cells, and activated lymphocytes. Mac-1 operates as a phagocytic receptor, has a role in myeloid cell transmigration and is also a receptor for iC3Bovine, CD54 (ICAM-1), CD102 (ICAM-2) and fibrinogen.