Recipient mice from donor splenocytes overexpressing miR-155 in T cells exhibit rapidly evolving aGVHD and short survival. (A) Schematic presentation showing the construct used to generate the LCK-miR-155 mice. (B) miR-155 expression (fold change) in the thymus and spleen from age- and sex-matched B6 LCK–miR-155 transgenic mice and B6 miR-155^−/− mice. Bars represent SD. (C) Schematic presentation depicting the different recipients F1 mice groups. (D) Clinical GVHD scores after transplantation from lethally irradiated F1 recipients transplanted with BM alone (n = 8), BM + LCK–miR-155 (n = 8), or BM + miR-155^+/+ (n = 8) splenocytes. P values were obtained by using t test. (E) Survival rate of the different recipient F1 mice groups. Comparisons between BM + miR-155^−/− spleen and BM + miR-155^+/+ spleen survival curves were performed using log-rank test. (F) Histopathologic GVHD scores of recipient tissues. A second cohort of mice was used for histopathologic analysis. Fourteen days after transplantation, mice from the indicated groups were killed and sections of the large bowel and liver were stained with H&E. P values were obtained by using t test. (G) Histopathologic evaluation of representative liver samples obtained from recipients of BM alone, BM + miR-155^+/+ spleen, and BM + LCK-miR-155 donor cells. Slides were stained with H&E. The arrows indicate lymphocytic infiltration in the recipient livers characteristic of GVHD.