Description: The WM-53 monoclonal antibody reacts with human CD33, also known as GP67 and P67, a 67 kDa type I transmembrane glycoprotein that is a member of the Siglec (sialic acid-binding Ig superfamily lectin) family. It is highly specific to the hematopoietic compartment and is expressed on monocytes, activated T cells, granulocytes, myeloid progenitors, and mast cells.