SIRPA and acute lymphoblastic leukemia: However, it has been shown that the disruption of CD47-SIRPα interaction by a blocking antibody against human CD47 (B6H12.2) enables phagocytosis of Acute Myeloid Leukemia Stem Cells (AML LSC) and Acute Lymphoid Leukemia (ALL) cells in vitro and inhibits tumor engraftment in vivo [8, 9].