CD200 and acute myeloid leukemia: Expression of CD200 at AML, both in secondary and at the diagnosis decreases activity of CD8+ T cell cytotoxic potential and the frequency of TNFα-, IL-2- and IFN-γ-producing CD4+/CD8+ memory T cells, which contributes to the increased risk of relapse and worse overall survival and is independent predictor of cytogenetics [88,89,90].