TNFRSF9 and graft versus host disease: CD137 expression was significantly greater in both the GVHD (80.09 ± 99.42) and non-GVHD (56.08 ± 51.21) groups than in the DED (6.35 ± 6.45) group, but no significant difference was noted between the GVHD and non-GVHD groups.