CD53 is a member of the transmembrane 4 superfamily, also known as the tetraspanin family. The function of this family in a number of different cell types may be involved in transmembrane signal transduction and regulation of cell proliferation and differentiation, or both. CD53 is broadly expressed on leukocytes, including B cells, T cells, monocytes and granulocytes. It has been demonstrated to be a specific and reliable marker for leukocytes. This antibody strongly labels normal and neoplastic cells with hematopoietic origin.