The Study Of Transfusion Donor Cells Before BMT Enhances Engraftment Of Haploidentical Transplantation

Background Hematopoietic stem cell transplantation has become one of the most effective therapy for patients who are suffering hematological malignant. But there are two-way rejections when we transplant allogeneic graft to patients, due to the dispatrty of MHC or HLA between individual and biological species, which are known as graft versus host reaction and host versus graft reaction. Because of the significant disparity of HLA between donor and recipient in haploidentical transplantation, intensity conditioning regiments are needed to overcome the severe reject reaction, including depletion of T cells in grafts and megadose of G-CSF mobilized hematopoietic stem cells. Nonmyeloablative hematopoietic stem cell transplantation reduces the intensity of conditioning and transplantation relanted toxicity. So it consists with modern therapeutic think. Nevertheless NST or mismatched-HSCT reduced the intensity of conditioning combining with disparity of HLA. They always reduced graft rejection and transplantation failure.As to be known, T cells and natural killer cells are the main factors mediating allo-rejection. It will be important to eliminate them or induce immune anergy for alloengraftment. It has been shown that depleting donor-alloreactive T lymphocytes can indeed reduce the incidence of GVHD, which indicates eliminating of alloreactive cells definitely reduces allogeneic rejection. So we presume that whether we can enhance engraftment by depleting of host alloreactive T lymphocytes in vivo. We scheme a novel regimen of transfusing donor cells before BMT followed by chemotherapy to eliminate the host alloreactive T cells thus induce immune tolerance. Ara-c is a kind of antimetabolites of miazines, which mainly affect the cell cycle of S stage. It is sensitive to alloreactive cells. Otherwise, it has been shown that cytotoxity will achieve peak when t cell exposure to alloantigen. We intensionly induced host alloreactive t cells directely against donor cell antigen by transfusion donor cell before BMT. Then we eliminated host alloreactive t cells before cellular immunity reach peak by interperitoneal injecting Ara-c. So when it was expoursed to the same alloantigen within short time, host will be tolerant as a result of the immunity against the antigen has been relatively exhausted.SectionⅠThe model establishment of haploidentical bone marrow transplantation using nonmyeloablative conditioningObjects Establish the mouse model of haploidentical bone marrow transplantation using nonmyeloablative conditioning, providing a platform for the study of immune tolerance induction and promoting engraftment.Methods One day before transplantation, the receptions female mousses CB6F1 received a dose of 450cGy total body irradiation (TBI). Then they were grouped into two groups randomly. Each was transfused 5×107 nucleated bone marrow cells from donor male mousses C57BL/6, the other were used as controlled. Then we monitored the recoverment of receptions hemogarm, engraftment by detection of sex determining gene(SRY) and donor cell chimerism after transplantation especially in the CD3+ cells.Results All mousses were alive and the white blood cell almost recovered to normal level within thirty days after transplantation. None mousse shown significant signs of graft-versus-host disease. Sex determining gene SRY can be detected in the peripheral blood from receptions in the experiment. Donor cell chimerism at days 14, 30 and 60 after tranaplantation in lymphocytes and monocytes and granulocytes were 23.8%±4.6%, 36.9%%±13.7%, 19.4%±7.5% vs 49.9%±3.6%, 53.2%±7.6%, 54.4%±4.8% vs 67.6%±3.1%, 51.6%±4.3%, 56.9%±2.9%. In CD3+ cells , chimerism rate were 4.4%±4.6%, 21.2%±6.4%, 54.4%±4.1%, respectively. No significant signs of graft-versus-host disease were observed.Conclusion The nonmyeloablative conditioning of single dose 450cGy TBI one day before transplantation can induce immune tolerance of receptions and enable donor bone marrow cells engraftment. The chimerism of donor cells was low level until the end of observation. SectionⅡThe study of transfusion donor cells before BMT enhancing engraftment of haploidentical transplantationObjects To observe whether giving donor cells before BMT can induce immune tolerance and enhance donor bone marrow cell engraftment.Methods There were three groups, Ara-C+TBI+BMT, SC+Ara-C+TBI+ BMT and BMC+Ara-C+TBI+BMT. Use CB6F1 female mouse as recipient and C57BL/6 male mouse as donor, at three days before transplantation donor lymphocytes or bone marrow cells were transfused by intravenous followed by two dose Ara-c at 24h and 48h later. One day before transplantation, the recipients received a dose of 450cGy total body irradiation (TBI). On the day of BMT recipients were transfused 5×107 nucleated bone marrow cells from donor male mousses C57BL/6. Then we monitored the recoverment of receptions hemogarm, donor cell chimerism in the CD3+ cells after transplantation and the survival from GVHD.Results There were two mousses dead in each group and all show disparity signs of graft-versus-host disease. Rapid white blood cell engraftment were observed in groups giving spleen cells and controlled at day 17(from 12d to 37d), while the group giving bone marrow cells was slightly slow at day 22. The chimerism of donor T cells from group giving spleen cell was as high as controlled , which was 93.5%±4.8% in the group of giving donor lymphocytes before BMT at day 30, that was significantly higher than the group of giving donor bone marrow cells (P<0.05). At day 60, the chimerism of the later group rising to 87.2%±7.4% as high as the group giving donor lymphocyte which was 91.7%±4.0%, P>0.05. All mousses showed signs of GVHD.Conclusion It seems that giving donor lymphocytes cells before BMT c an enhance haploidentical bone marrow cells engraftment.