Donor-derived regulatory T-cells (Tregs), with potential immunomodulating activity. Tregs are a subset of CD4+ T cells that express high levels of CD25 (interleukin 2 receptor) and the transcription factor Foxp3. The donor CD4+CD25+ Tregs modulate immune responses and may induce tolerance to allogeneic organ transplants, such as hematopoietic stem cell transplants (HSCTs), thereby preventing graft-versus-host disease (GVHD). Check for active clinical trials using this agent. (NCI Thesaurus)