Tregs expanded with cell-based aAPCs offer increased protection from GVHD mortality and pathology over Tregs expanded with bead-based aAPCs. Cord blood Tregs were purified, expanded in vitro using bead- or cell-based aAPCs, and injected along with allogeneic PBMNCs into clodronate-treated, irradiated Rag2^−/−, γ_c^−/− mice as in Figure 5. (A) Kaplan-Meyer survival curve showing increased survival of mice receiving human PBMNCs with or without groups of Tregs in a 3:1 ratio (ie, 30 × 10⁶ PBMNCs and 10 × 10⁶ Tregs). For groups PBMNCs, CD3/28 beads, and KT32, n = 8, 10, and 10, respectively. P ≤ .05 for each Treg-treated group compared with PBMNCs. (B) Enumeration of Tregs in blood of animals on the indicated days after transfer, showing increased persistence for KT32-expanded Tregs. P < .04 on day 10. (C) Decreased percentage of human CD4⁺ cells were observed in blood and spleen from Treg-treated animals that survived to day 67.