Donor Langerhans cells are not required for GVHD in the B6.C→BALB/c strain pairing. BALB/c mice were irradiated and reconstituted with Tg⁺ or Tg⁻ B6.C BM with or without Tg⁺ B6.C CD4 cells. (A) Percentage weight loss. Two independent experiments are shown as left and right panels. Data were not combined due to differences in the kinetics and magnitude of weight loss in the 2 experiments. Experiment 1: P < .028 comparing each CD4 recipient group to its respective BM-alone group at all measurements; P > .05 comparing Tg⁺ and Tg⁻ CD4 recipients at all measurements except days 13, 15, and 34). Experiment 2: P < .026 comparing each CD4-recipient group to its respective BM-alone group from day +33; P > .05 comparing percentage weight loss of Tg⁺ and Tg⁻ CD4 on all days except day +2 and days +16 to +23. (B-C) Combined data from 2 experiments shown in A. (B) Percentage unaffected by skin disease (P < .003 comparing each CD4 recipient group to its respective BM-alone groups; P > .384 comparing Tg⁺ and Tg⁻ CD4-recipient groups). (C) Clinical scores of mice affected by skin GVHD (P > .179 comparing Tg⁺ and Tg⁻ CD4 recipient groups at all time points). (D) Pathology scores. P values are noted in the figure.