Figure 4.

Recipient but not donor and third-party Tregs prevent BM rejection. Groups of B6 mice were grafted with 15–20 × 10⁶ Balb/c BM cells under the cover of costimulation blockade (anti-CD154, CTLA4Ig) and rapamycin (○ no Tregs; control n = 5) and were additionally treated with 3 × 10⁶ nTregs of recipient (■  n = 4), donor (◆  n = 4), or third-party (∆  n = 3) origin. Donor (H-2D^d+) chimerism among leukocytes of T cell (CD4⁺ and CD8⁺), B cell (B220⁺), and the myeloid (Mac1⁺) lineage was assessed by flow cytometry of peripheral blood at multiple time points and is shown as mean percent (error bars indicate standard deviation). ^∗∗ p < 0.005, ^∗ p < 0.05 (Student's t-test for recipient Tregs versus each other group).