CD8A and chronic myelogenous leukemia, BCR-ABL1 positive: CD8+ T cells in CML exhibit a similar dysfunctional phenotype, with decreased expression of TCRζ (T cell receptor ζ) and limited cytotoxic function and secretion of effector interferon γ (IFN-γ) and tumor necrosis factor α (TNF-α) [35,36].