The ability of the immune system to differentiate self from nonself is critical in determining the
immune response to antigens expressed on transplanted tissue. Even with conventional
immunosuppression, acceptance of the allograft is an active process often determined by
the presence of regulatory T cells (Tregs). Tregs classically are CD4+ cells that constitutively
express high levels of the IL-2 receptor α chain CD25, along with the transcription factor
Foxp3. The use of Tregs in the field of solid organ transplantation is related specifically to the …