Lethally irradiated B10.BR recipients were injected with 10⁷ BM (*) and 1 × 10⁶ CD4⁺CD25⁻ T cells from WT (▼) or Stat5b-CA TG (●) mice. Mice were not challenged with A20 lymphoma cells and were monitored exclusively for GVHD lethality (A) and weights (B). Other cohorts of mice treated as in panel A also were given 10⁵ A20 lymphoma cells on day 0 of BMT and were then monitored for survival (C) and weights (D). P values are as indicated. Data are from 1 experiment with 10 mice per group. Separate cohorts of mice were analyzed for bioluminescent imaging on days 7, 14, and 21. Data shown are the bioluminescence emissions (E) and the quantification of bioluminescence based on photons/sec/cm² emission (y-axis) and days after BMT (x-axis; F). The SD of the mean is also shown.