To investigate biomarkers that identify alloreactive T cells associated with either beneficial GvL or detrimental aGvHD, we collected graft samples and two post-transplant follow-up blood samples (day 30 and day 100) of ten AML patients undergoing hematopoietic stem cell transplantation and profiled over 777,000 CD45+ leukocytes in total by combinatorial barcoding-based mega-scale single-cell RNA sequencing. This evidence concerns the gene PTPRC and acute myeloid leukemia.