CD33 is a transmembrane protein of the sialic acid-binding immunoglobulin-like lectin (Siglec) family. It belongs to the immunoreceptor tyrosine-based inhibitory motif (ITIM)-containing molecules able of recruiting protein tyrosine phosphatases SHP-1 and SHP-2 to signal assemblies, and these ITIMs are also used for ubiquitin-mediated removal of the receptor from the cell surface. CD33 is expressed on cells of myelomonocytic lineage, binds sialic acid residues in N- and O-glycans on cell surfaces, and is a therapeutic target for acute myeloid leukemia. Further, CD33 is found on granulocyte and macrophage precursors in the bone marrow, but is not on pluripotent stem cells. CD33 is also expressed on, and is a useful marker for, peripheral monocytes. CD33 is useful for distinguishing myelogenous leukemia cells from lymphoid or erythroid leukemias. Diseases associated with CD43 dysfunction include gallbladder lymphoma and extracutaneous mastocytoma.
CD33; CD33 antigen (gp67); CD33 molecule transcript; FLJ00391; gp67; Myeloid cell surface antigen CD33; sialic acid binding Ig-like lectin 3; Sialic acid-binding Ig-like lectin 3; Siglec-3