HLA-E and acute myeloid leukemia: AML and B-ALL cell lines were analyzed by flow cytometry to determine the expression of each target antigen (CD19 and CD276) as well as relevant ligands for inhibitory receptors including CTLA-4 (CD80 and CD86), NKG2A (HLA-E), PD-1 (CD273 & CD274), TIGIT (CD112 and CD155) and TIM-3 (CD66a and Gal-9) (Figure 1) [18].