OBJECTIVETo investigate whether the fetal immune tolerance induction could replace the HLA typing for hematopoietic stem cell transplantation.

METHODSImmune tolerance of SD rats was induced by injecting host Wistar rats peripheral blood mononuclear cells into yolk sac of the embryo, afterward the mature male offsprings were used as donor. The host female recipients received lethal dose irradiation and bone marrow transplantation(BMT). The Wistar rats transplanted with bone marrow from donor and unrelated SD rats as well as the rats which received radiation alone were used as control. The survival, histopathologically GVHD, the mental status, food and water intake, coat characteristics, activities were observed. Forty days after BMT, autologous and allogenous skin transplantation between donor and recipient rats was performed to observe the engraftment of solid organ.

RESULTSThe survival of the rats received bone marrow grafts from the immune tolerant donor was significantly longer than that of control groups (30 day survival rates were 86.7%, 6.7%, 0%, and 0% respectively), and there was no histopathologically GVHD observed, while in the sham group, the manifestations of GVHD was clearly visible. The skin engraftment rate between the host and the immune tolerant donor was significantly higher than that among non-related rats (84.6% and 0% respectively).

CONCLUSIONThe induction of immune tolerance in embryo can overcome the HLA barrier and provide a good donor for hematopoietic stem cell and solid organ transplantation.