[Immune reconstitution after allogeneic stem cell transplantation using nonmyeloablative or reduced-intensity...

A number of reduced-intensity conditioning(RIC) regimens, which mainly consisted of potent immunosuppressive agents but not of myeloablative agents, has been explored in order to achieve successful engraftment and subsequent graft-versus-leukemia/tumor effect. Because of the decreased regimen-related toxicity, RIC regimens have replaced myeloablative regimens, particularly for those who are not eligible for high dose chemoradiotherapy due to advanced age or organ dysfunction. However, allogeneic stem cell transplantation(allo-SCT) using RIC regimens sometimes end up with mixed chimerism and may require donor-lymphocyte infusion to achieve complete chimera. Furthermore, strong immunosuppressive agents used in RIC regimens might contribute to the delayed immune recovery after allo-SCT, which might subsequently increase the incidence of infections. These findings suggest that the hematopoietic and immune reconstitution after allo-SCT using RIC regimens is different from that using conventional regimen. In this article, hematopoietic reconstitution, phenotypic analysis of lymphocytes, infections, and graft-versus-host disease after allo-SCT using RIC regimens are discussed, comparing with those using conventional regimens.