CD4 and acute myeloid leukemia: Upregulation of CD200 in AML cells is associated with an increased population of tumor-suppressive FoxP3+ Tregs, low T-cell cytokine production due to reduced MAPK and STAT3 signaling, impaired T-cell metabolism, decreased production of CD107a+CD8+ memory T cells, reduced TNFα, IL-2, and IFNγ production in CD4+ memory cells, and upregulation of the exhaustion marker TIM-3 in tumor-infiltrating CD4+ bone marrow T cells [47,48,49,50].