CD73 deficiency leads to increased expansion of allogeneic T cells after BMT. All BMTs were performed on lethally irradiated mice as described in “BMT model and induction of GVHD.” (A) Cd73^+/+ and Cd73^−/− C57BL/6 mice (3 each) were transplanted with 5 × 10⁶ BM cells and 1 × 10⁶ CD4⁺/CD8⁺ splenic T cells from a Cd73^+/+luc⁺-transgenic FVB/N donor. In vivo expansion of luc⁺ T cells was quantified by BLI and is shown at sequential time points (mean ± SEM; representative results from one of 2 independent experiments). *P < .05. (B) Cd73^+/+ or Cd73^−/− C57BL/6 mice were transplanted with 5 × 10⁶ BM cells and 10 × 10⁶ spleen cells from Cd73^+/+ or Cd73^−/− BALB/c mice, respectively. Six to 7 days after BMT, numbers of donor CD4⁺ and CD8⁺ T cells in recipient spleens were determined by flow cytometry (mean ± SD; n = 3-5/group). *P < .05. The results are representative of 3 independent experiments. (C) Cd73^+/+ or Cd73^−/− C57BL/6 mice were transplanted with 5 × 10⁶ BM cells and 10 × 10⁶ CFSE-labeled spleen cells from Cd73^+/+ or Cd73^−/− BALB/c mice, respectively. Three days later, spleens were harvested and proliferating donor CD4⁺ and CD8⁺ T cells were identified by loss of CFSE intensity. The results are representative of 3 similar independent experiments (n = 3-5/group). Data are summarized as the percentage of proliferating donor CD4⁺ and CD8⁺ T cells (mean ± SD). *P < .05.