CCR2^-/- CD8⁺ T cells cause less gut and liver damage than WT CD8⁺ T cells while no difference is observed for skin, thymus, and bone marrow. Lethally irradiated (1300 cGy) C3FeB6F1 mice received 5 × 10⁶ TCD WT BM cells in combination with 3 to 4.5 × 10⁶ WT (▪) or CCR2^-/- (□) CD8⁺ T cells. (A-C) Small bowel, large bowel, and liver were taken on day 21 and day 55. Hematoxylin and eosin–stained slides were analyzed and scored for histopathologic damage. Shown is the mean ± SEM for 8 to 10 mice per group per time point. (D) Skin GHVD was determined on day 21 and day 55 by the number of apoptotic keratinocytes/mm epidermis. Shown is the mean ± SEM for 8 to 10 mice per group per time point. (E) Thymic cellularity (total cell counts and CD4⁺CD8⁺ thymocytes) was determined by FACS on day 21. Shown is the mean ± SEM for 7 mice per group. (F) Peripheral blood was obtained at weeks 1, 3, 5, and 9 after BMT and CBCs were determined. Shown is the mean ± SEM for WBC counts for 7 to 10 mice per group per time point.