Abstract
Effective control of the graft-versus-host disease (GVHD) and immune reconstitution are crucial in improving the outcome of allogeneic hematopoietic stem cell transplantation (HSCT) as well as the quality of life of the transplant survivors. Recent basic and clinical studies have deepened our understanding of the mechanisms of the immunological sequelae of HSCT, GVHD, and compromised immune systems. Based on the findings, various novel approaches have also been developed and tested clinically. However, further studies are necessary to develop therapeutic strategies with significant clinical benefits.