Transfer of CD25- βgalTCR T cells into lymphopenic recipients, whether arrβgal × Rag(-/-) or Rag(-/-), demonstrated the development of a systemic regulatory response in βgal+ recipients. (A) CD25+Foxp3+ status of the CD4+ donor cells prior to transfer. (B) Ear swelling of control and recipient mice 10 – 11 weeks post-transfer of the indicated T cell populations. CD25-depleted naive βgalTCR T cells, or CD25-enriched T cells from βgalTCR mice, were given at 2.5 × 105/mouse. CD25-enriched T cells from B10.A mice were administered at 5 × 104/mouse, where indicated, with the CD25-depleted cells.