CD33 and acute myeloid leukemia: Cell surface antigens that fulfill these criteria in several AML variants (most cases) include, among others, CD33 (Siglec-3), CD44 (Hermes), CD45 (common leukocyte antigen), CD47 (integrin associated protein = IAP) and CD123 (interleukin-3 receptor alpha-chain = IL-3RA) (Table 1) [34,35,36,37,38,39,40,41].