Achieving a graft-versus-leukemia (GVL) effect while suppressing graft versus host disease (GVHD) is the ultimate goal for allogeneic hematopoietic cell transplantation. Circulating CD8 regulatory T cells (Treg) that are capable of immunosuppression and cytolysis are rare. Therefore, we developed a protocol to generate human CD8 induced Tregs that are expansile and possess dual CD8 CTL cytotoxicity, consistent with their cell surface and intracellular expression patterns. When transduced with a chimeric antigen receptor, CD8 iTregs and cytotoxic T cells are equally cytolytic against their targets in vitro and in vivo, reflecting their dual function. Mechanism(s) underlying these properties will be discussed.