P2RX7 and graft versus host disease: Whether this reflects differences in pharmacokinetics or affinity between the two Nbs remains unknown, although these Nbs display similar IC50 values (2.0 and 2.8 nM for 1C81 and 13A7, respectively)17, 36 Of note, the anti‐P2X7 Nb treatment, especially with the anti‐h/mP2X7 Nb, reduced histological GVHD in the liver and lungs, with a similar but non‐significant reduction in the skin.