Harnessing CD8⁺CD28^- Regulatory T Cells as a Tool to Treat Autoimmune Disease

T regulatory cell therapy presents a novel therapeutic strategy for patients with autoimmune diseases or who are undergoing transplantation. At present, the CD4⁺ Treg population has been extensively characterized, as a result of defined phenotypic and functional readouts. In this review article, we discuss the development and biology of CD8⁺ Tregs and their role in murine and human disease indications. A subset of CD8⁺ Tregs that lack the surface expression of CD28 (CD8⁺CD28^- Treg) has proved efficacious in preclinical models. CD8⁺CD28^- Tregs are present in healthy individuals, but their impaired functionality in disease renders them less effective in mediating immunosuppression. We primarily focus on harnessing CD8⁺ Treg cell therapy in the clinic to support current treatment for patients with autoimmune or inflammatory conditions.