CD15 is expressed on neutrophils, eosinophils and monocytes, but not on platelets, erythrocytes, normal B and T cells. It is also present in embryonic tissues and adenocarcinomas, myeloid leukemias and Reed-Sternberg cells [1,2]. CD15 antibodies recognize the terminal trisaccharide structure which is also referred to as the Lewis x antigen. This structure is found on a variety of glycoproteins and glycolipids at the cell surface [3,4]. CD15 antibodies have been shown to affect a number of cell activities, but it is difficult to distinguish between effects on the CD15 structure itself and effects mediated by proteins which happen to carry the CD15 epitope. CD15 antibodies can mediate complement activation and may have potential therapeutic value in the killing of CD15-expressing tumor cells [2].Synonyms: Lacto-N-Fucopentaose III, Lewis X, SSEA1, Stage-Specific Embryonic Antigen, X-Hapten