Hyun et al. analyzed CD11b+CD33+HLA-DR- MDSC-like blasts from patients with AML, and found that MDSC-like blasts showed higher expression of arginase I and inducible nitric oxide synthase, significantly suppressing CD8+ T cell proliferation induced by phytohemagglutinin A. They also reported that patients with a high number of MDSC-like blasts at the time of diagnosis showed shorter overall survival13. Here, NOS2 is linked to acute myeloid leukemia.