Already in 2011, a study focusing on the PD-1/PD-L1 axis reported increased PD-L1 expression on myeloid leukemia cells after IFNγ and TNFα stimulation as well as PD-1 expression on minor histocompatibility antigen (MiHA)-specific memory CD8 T cells (35). Here, CD274 is linked to myeloid leukemia.