Abstract
The presence of multilineage hematopoietic stem cells in liver allograft produces a complex bidirectional cell communication in liver transplantation. Although direct contribution of HLA is low and a reduction of immunosuppression is easy after liver transplantation, a contribution of humoral immunity is also strongly suggested. Various factors are involved in the pathogenesis of liver allograft rejection, and many factors remain to be clarified in the pathogenesis of refractory and/or chronic rejection. Apart from one-way HLA matching, the factors contributing to the pathogenesis of fatal GVHD, the risk of which is unnegligible especially in living related liver transplantation, are largely unknown. There exists a wide window between HVG and GVHD in bidirectional cell traffics in liver transplantation, which should play important roles in the acquisition of immune tolerance.
