IL-21R KO T cells cause decreased GVHD and lead to increased regulatory T cells. (A) Lethally irradiated BALB/c mice were reconstituted with either BM-TCD only (n = 9), 1 × 106 IL-21R KO T cells + BM-TCD (n = 15), or 1 × 106 WT T cells + BM-TCD (n = 15). Curves represent combined data from 2 independent experiments. (B) Lethally irradiated BALB/c mice received either BM-TCD only (n = 9), 5 × 105 IL-21R KO CD4 T cells + BM-TCD (n = 15), or 5 × 105 WT CD4 T cells + BM-TCD (n = 15). Curves represent combined data from 2 independent experiments. (C,D) Transplant recipients were scored on a weekly basis for 5 clinical GVHD parameters: weight loss, activity, kyphosis, fur ruffling, and skin flaking. Scores range from 0 to 2 for each parameter, and animals are killed once a total score of 5 is attained. Curves represent the average score of each group at each time point. Shown are combined data from 2 independent experiments. (E) Lethally irradiated BALB/c mice were reconstituted with B6 BM-TCD and 1 × 106 B6 WT or 1 × 106 B6 IL-21R KO T cells. Spleens were harvested on days 7, 14, and 21 after BMT and stained for FACS analysis of donor CD4+CD25+Foxp3+ T-regs or CD4+Foxp3− nonregulatory T cells. Data represent 2 combined independent experiments on day 7 (n > 19), day 14 (n = 18), and day 21 (n = 15). (F) Lethally irradiated BALB/c mice were reconstituted with CD45.1 B6 BM-TCD and 5 × 105 CD45.2 B6 MACS-purified T cells. Transplanted T-cell populations were either unfractionated or depleted of T-regs by sorting for CD25− cells. Spleens were harvested on day 21 after BMT and analyzed by FACS for Foxp3 expression among donor CD4 T cells. Data represent 2 combined independent experiments with 8-11 total recipients per group. *P < .05, **P < .01, and ***P < .001 for WT versus KO T cells.
