Finally, the anti-hP2X7 mAb reduced clinical and histological GVHD in a humanised mouse model, which corresponded to increased proportions of hTregs, hNK T cells, and hNK cells and decreased the proportions of hTh17 cells and hTh17:hTreg ratio, collectively demonstrating that donor (human) P2X7 can directly contribute to GVHD progression. Here, P2RX7 is linked to graft versus host disease.