Rapid restoration of splenic Th2 suppression by Treg transfer. The magnitude and Th bias were compared for wild-type mice (WT), Foxp3^DTR mice injected with DT (DTR), and Foxp3^DTR Ly5.1 mice injected with DT (on day 0) and then injected with 5 × 10⁶Ly5.2 Foxp3^GFP CD4 T cells 7 days later (i.v.Treg). (A) Splenic cellularity. (B) Proportion of T-cell activation, as measured by CD44 expression on CD4⁺ T cells. (C) Frequency of CD4⁺CD44^hiFoxp3⁻ T cells producing IFNγ (□) and IL-4 (■). Within the i.v.Treg group, only the responses within the host Ly5.1⁺ cells were measured; n = 3/group. Error bars indicate SD.