CD47 and neoplasm: One may speculate that human T cells engineered to secrete decoys of CD47 augment tumor control and persist upon ACT in one in vivo study (or at least a proportion of them do) but not in another study because of the amount of decoy secreted, the affinity of the decoy and Fc region used, the level of CD47 on the T cells and the extent of blockade (57), the proliferative capacity of the T cells, and differences in the phagocytic threshold of the endogenous macrophages.