Immune deregulation in lower-risk MDS and higher-risk MDS. (Left panel) Lower-risk MDS are characterized by the hyperfunction of immune cells. CD8⁺ T cells are increased in number and functionally activated. (Right panel) Higher-risk MDS are characterized by an immunosuppressive environment that causes immune escape. CD8⁺ T cells are significantly decreased, whereas the number of Treg cells is increased. MSC, mesenchymal stem cell.