[Immunobiology of mini-transplant]

Mini-transplant has become much more popular since mid-90's worldwide. Mini-transplant has not only provided opportunity for cure to many patients who otherwise could not undergo allogeneic stem cell transplant, but also has lead to many new findings which may answer some questions related to scientific basis of allogeneic stem cell transplantation. Mini-transplant has shown that engraftment of donor stem cells can be achieved without complete ablation of host bone marrow. Role of post-transplant immunosuppression has also been clarified through the experience of mini-transplant. In this review, we discuss the mechanism and basics under the theory of mini-transplant.