CD36 Influences Leukemia Progression in MLL-AF9-Driven AML by Modulating the Leukemia Immune Microenvironment

CD36, a fatty-acid translocase, is increasingly implicated in acute myeloid leukemia biology and treatment resistance, yet its contribution to leukemogenesis is still unclear. Using the MLL-AF9 model, we transduced hematopoietic stem/progenitor cells (HSPCs) from Cd36-knockout (KO) or wild-type (WT) mice and assessed leukemic potential with in vitro assays, transplants, and transcriptomic, metabolomic, and immune profiling. Both Cd36KO- and Cd36WT-HSPCs underwent efficient MA9-driven transformation, with comparable colony formation and Hox/Meis1 pathway activation, indicating Cd36 is dispensable for leukemic initiation. However, Cd36 deletion markedly attenuated disease progression, reducing leukemic burden and extending survival in irradiated mice (median 22 vs. 15 days, P = 0.001). Effects were strikingly amplified in immunocompetent, non-irradiated recipients (median 63 vs. 22 days, P = 0.002), revealing immune-dependent suppression. Immune profiling showed enhanced CD4⁺ and CD8⁺ T cell infiltration, reduced CD4⁺CD25⁺ regulatory-like cells, and lower Tim-3 expression in Cd36KO-MA9 spleens, consistent with a less exhausted, more effective anti-leukemic T cell response. Despite enhanced T cell infiltration, TCR repertoires remained conserved, indicating functional reprogramming rather than clonal selection. Consistent with a suppressive leukemia immune microenvironment, RNA-seq gene set enrichment analysis identified upregulation of inflammatory (TNFα/NF-κB) and hypoxic pathways in Cd36WT-MA9 cells. Untargeted metabolomics revealed metabolic shifts in Cd36KO cells, involving a reduction in three key metabolites, UDP-GlcNAc, UDP-Galactose/UDP-Glucose, and O-Phospho-L-Serine, that likely support an immune evasion mechanism. These findings demonstrate that while Cd36 is not essential for MLL-AF9-mediated transformation, its cell-intrinsic expression in leukemic cells suppresses anti-leukemic immunity and accelerates progression. This positions CD36 as a promising target to enhance immune surveillance and limit AML aggressiveness.