Adoptive transfer of Treg cells improves the protective effect of CD4⁺Foxp3^- T cells.

(A) Survival curves of Rag1^-/- mice infected with Pb18 after adoptive transfer of 2×10⁵ Treg cells, 2×10⁶ CD4⁺Foxp3^- T cells, 2×10⁵ Treg cells + 2×10⁶ CD4⁺Foxp3^- T cells, or vehicle only (p < 0.05 between PBS and Treg; p < 0.001 between PBS and CD4⁺Foxp3^- T cells; p <0.001 between PBS and CD4⁺Foxp3^- + Treg; p < 0.05 between Treg and CD4⁺Foxp3^-; p < 0.001 between Treg and CD4⁺Foxp3^- + Treg; n ≥ 13). (B and C) Analysis of disease severity through recovery of CFU from lungs, livers and spleens from Rag1^-/- mice infected with Pb18 after adoptive transfer of 2×10⁵ Treg cells, 2×10⁶ CD4⁺Foxp3^- T cells, 2×10⁵ Treg cells + 2×10⁶ CD4⁺Foxp3^- T cells, or vehicle only. Horizontal bars indicate the mean value in each group (* = p < 0.05; ** = p < 0.005; *** = p < 0.001; n ≥ 10).