CD80 and acute myeloid leukemia: Intriguingly, AML and MDS blasts can express costimulatory molecules such as B7-1 (CD80), B7-2 (CD86), and B7-H2 (ICOS-LG) which normally take part in cancer immunity; nonetheless, these malignant cells survive immune reactions through acquisition of adaptive resistance which is essentially mediated by IFN-γ5–7.