In conclusion, mega-scale single-cell monitoring of graft and hematopoietic immune cell reconstitution allowed us to demonstrate that MDGA1 and ADGRG1 may function as complementary biomarkers expressed by distinct circulating T cells that are associated with divergent outcomes in AML patients, enabling precise risk stratification of alloHSCT outcomes and presenting potential therapeutic targets. Here, ADGRG1 is linked to acute myeloid leukemia.