Transfer of CD4⁺ T cells from [H2-Ab1^−/− → C3H] mice transmitted GVHD in [B6 → C3H] chimeras. The [B6 → C3H] and [C3H → C3H] chimeric mice were sublethally irradiated and injected with splenic CD4⁺ T cells (1 × 10⁷) isolated either from [WT → C3H] or [H2-Ab1^−/− → C3H] mice, respectively. The survivals after transfer (A) and weight change (B) are shown (n = 3 to 5 per group). [C3H → C3H] chimeric mice were transferred with [WT → C3H] CD4⁺ T cells (□) or [H2-Ab1^−/− → C3H] CD4⁺ T cells (○). [B6 → C3H] chimeras underwent transplantation with [WT → C3H] CD4⁺ T cells (▪) or [H2-Ab1^−/− → C3H] CD4⁺ T cells (•). *P < .05, **P < .001.