Proliferation in MLCs of CD4⁺ and CD4⁺CD25⁻ T cells from DA rats with long surviving PVG allografts after restoration with IL-2– or IL-4–alloactivated CD4⁺CD25⁺ Tregs. (A) The proliferative response of CD4⁺CD25⁻ T cells from hosts restored with IL-2/PVG-alloactivated (Ts1) cells against PVG and Lewis stimulator cells was not significantly different, but both were greater than response without allogeneic stimulator cells (P < .03 for PVG and P < .001 for Lewis). (B,C) Proliferative response of CD4⁺ T cells (B) and CD4⁺CD25⁻ T cells (C) from tolerant hosts restored with IL-4/PVG–alloactivated CD4⁺CD25⁺ T cells (Ts2) to PVG (●) and Lewis (□) stimulator cells in a limiting dilution assay. At all dilutions of responder cells, the proliferation to specific donor PVG was as great as to Lewis, indicating there was no clonal deletion. For CD4⁺ T cells, the response to PVG at 1 dilution was greater (*P < .05).