Transfer of naive CD4⁺ T cells from CCR6-deficient mice to MHC class II–mismatched recipients results in milder GvHD. Survival (A-C) and animal weight at indicated days (D-F) are shown for bm1 and bm12 (n = 8) mouse recipients of C57BL/6 WT (○) and CCR6-deficient (□) CD4⁺ and CD8⁺ T cells, as indicated. Recipient weight is also shown prior to cell transfer (▵). Differential time course of GvHD symptom development in BALB/c recipients of C57BL/6 WT and CCR6-deficient naive CD4⁺ or CD8⁺ T cells. Irradiated recipient mice (n = 10) received 4 × 10⁶ isogeneic T-cell–depleted BM cells and 3 × 10⁵ naive CD4⁺ or CD8⁺ T cells from C57BL/6 WT (○) or CCR6-deficient (□) donors. For the cell transplants indicated, data are shown for GvHD mean clinical score (G), body weight (H), and percent survival (I-J), including control mice that received only isogeneic T-cell–depleted BM cells (▵). Results are shown from 1 of 2 independent experiments. Statistical analyses using Student t test comparing weights and GvHD symptom score from WT versus CCR6-deficient T-cell recipients yielded P < .001 (D), P > .5 (E-F), P = .01 (G), and P > .5 (H). Kaplan-Meier survival curves were established for each group (A-C, I-J) with the indicated P values for the log-rank test.