Serum proinflammatory cytokines are increased in CD73-deficient allogeneic BMT recipients, and CD73 is not required for T-cell migration in vitro. (A) Cd73^+/+ or Cd73^−/− C57BL/6 mice were exposed to lethal irradiation and transplanted with 5 × 10⁶ BM cells and 10 × 10⁶ spleen cells from Cd73^+/+ or Cd73^−/− BALB/c mice, respectively. Six to 7 days later, serum was collected from recipients, and the concentrations of IFN-γ and IL-6 were determined by ELISA (n = 5/group, mean ± SD). *P < .05. The data are representative of 3 similar independent experiments. (B) In vitro migration of CD4⁺ and CD8⁺ T cells purified from Cd73^+/+ or Cd73^−/− C57BL/6 mice along a CXCL12 gradient as described in “T-cell migration assay.” The data were normalized to the migration of Cd73^+/+ T cells in the presence of CXCL12 and are expressed as mean fold increase ± SEM. *P = .0014. Pooled results are shown from 4 independent experiments performed with 3 or 4 replicates each for the CXCL12 containing wells. (C) Lethally irradiated BALB/c mice (n = 4) were transplanted with 5 × 10⁶ BM cells and 3 × 10⁵ CD4⁺/CD8⁺ T cells from a C57BL/6 donor. On day 8, CD4⁺ and CD8⁺ donor splenic T cells were analyzed for the expression of CXCR4 by flow cytometry. Open histograms represent isotype control staining.