Transfer of CD4⁺ T cells from [H2-Ab1^−/− → C3H] mice transmitted chronic GVHD in the secondary recipients when reconstituted with B6 TCD-BM but not C3H TCD-BM. A total of 1 × 10⁷ [H2-Ab1^−/− → C3H] CD4⁺ T cells were transferred to lethally irradiated C3H mice together with TCD-BM from C3H (○) or B6 (•) mice. The survivals (A) and weight changes as the mean ± SE (B) after transfer are shown; n = 3 to 6 per group. (C) Appearances of C3H recipients of pathogenic CD4⁺ T cells with C3H TCD-BM (left) and those with B6 TCD-BM (right) 7 weeks after transfer are shown. (D) Skin pathologic scores at 10 weeks after transplantation are shown as the mean ± SD. (E) CBCs were measured 7 weeks after transfer. Data are expressed as the mean ± SD. *P < .05, **P < .001.