ICOS and acute myeloid leukemia: This study aimed to investigate the relationship between the expression of PD-1 and ICOS on mononuclear cells (MNCs) isolated from the peripheral blood of acute myeloid leukemia (AML) patients and their response to induction chemotherapy.<h4>Materials and methods</h4>Peripheral blood samples (5 cc) were collected from 56 AML patients at first diagnosis before and after the induction therapy regimen for AML.