The reason why especially PD1/PD-L1 blocking agents are not efficacious is not well-understood but it may be due to the contribution of different IC ligand/receptor interactions that determine the function of T cells in AML.<h4>Methods</h4>To analyze the interactions of IC ligands and receptors in AML, we performed a comprehensive transcriptomic analysis of FACS-purified leukemia stem/progenitor cells and paired bone marrow (BM)-infiltrating CD4<sup>+</sup> and CD8<sup>+</sup> T cells from 30 patients with AML. The gene discussed is CD4; the disease is acute myeloid leukemia.