Recognizes an N-glycosylated glycoprotein of 120kDa with intra-chain disulfide bonds, identified as CD50 or ICAM-3 (WS: IV & V). Its epitope localizes in the D2 extracellular domain and is resistant to neuraminidase and proteases. CD50 is the major ligand for LFA-1 (CD11a/CD18) and may have signalling role to increase adhesion. It is expressed on thymocytes and T lymphocytes and is resistant to treatment with phosphatidylinositol (PI) phospholipase C. This MAb inhibits primary mixed lymphocyte culture (MLC) but not secondary MLC, cytotoxicity or proliferation induced by mitogens. It blocks binding of NK1-L16 stimulated T cells to L cells expressing CD50. This MAb is excellent for staining of formalin/paraffin tissues.