PDCD1 and acute myeloid leukemia: In a model of acute myeloid leukaemia (AML), it was shown that, although IL-33 administration alone can enhance CD8+ T-cell-mediated responses and prolong survival, the combination of IL-33 stimulation with PD-1 blockade induced even more potent antileukemic effects, including complete regression in a significant number of treated mice [115].