In this study, we show that a subset of foetal lymphoid-primed multipotent progenitors (LMPPs) expressing the Colony-Stimulating Factor 1 receptor (CSF1R) gives rise to acute myeloid leukaemia (AML) upon KMT2A::MLLT3 induction in a mouse model, with the myeloid phenotype, at least in part, being dependent on CSF1R signalling. This evidence concerns the gene MLLT3 and acute myeloid leukemia.