CD8⁺ regulatory T cells in solid organ transplantation

Purpose of Review: Recent advances in phenotypic identification of CD8 T cells with regulatory properties has allowed better definition of this subset of CD8 Tregs (also called CD8 T suppressor cells in the past). Analysis of their potential contribution in transplantation has attracted most of the interest in the past few years. A better understanding of the mechanisms of action and role of antigenic specificity of the different subtypes of CD8 Tregs and their potential in solid organ transplantation will bring considerable advances in the field. This review will focus and summarize the potential of this subset in cell-based treatments of human transplantation and highlight major discovery in the last months. Recent Findings: Identification of markers such as PD-1 has allowed better definition of the different CD8 Tregs subsets. Recent animal and human studies have identified mechanisms used by antigen-specific CD8 Treg cells in suppressing anti-allograft immune responses such as perforin-dependent cytotoxicity. New strategies of ex-vivo stimulation (through the T-cell receptor or not) of CD8 Tregs have shown future direction for solid organ transplantation. Summary: CD8 Treg cells represent a subset of regulatory T cells with great potential for future therapeutic application and researchers are moving ahead for a better understanding of their action in antigraft immune response suppression.