Anti-CD137 blocks lethal GVHD induced by donor CD4+ and CD8+ T cells. On day 0, Balb/c recipient mice were sublethally irradiated and reconstituted with 5 × 106 BM cells and 6 × 106 total spleen/lymph node cells from B10.D2 donor mice. Anti-CD137 (200 μg per mouse) was administered 30 days after disease induction, and changes of mean clinical scores and survival rate were counted thereafter (n = 7 for control Ig group; n = 12 for anti-CD137 group). (A) Survival rate. (B) Changes of mean clinical scores. (C) Comparison of the percentage of mice with ulcers between day 30 and day 59 after disease induction. (D) Gross observation of the skin lesions in the posterior neck area at day 59 after disease induction. (E) Histopathology of the skin at day 59 after disease induction (H&E staining). Images were acquired using an Olympus BX51TF light microcope, 4×/0.10 oil objective, and an Olympus C-3000 zoom camera and processed using Image-Pro Plus, version 4. Original magnification, × 40.
