CD33 and leukemia: To further evaluate the role of ME2 in vivo development of leukemia, ME2-silenced THP-1 and MV4-11 AML cells as well as control cells were implanted into mice with advanced severe immunodeficiency (ASID); the percentage of CD33 + and CD45 + cells in the peripheral blood (PB) and bone marrow (BM) compartments were used to assess the burden of AML (Fig. 3A).