To Induce Specific Immunologic Tolerance And Prevent Graft Versus Host Disease In Xenogeneic Bone Marrow Transplantation Between Mouse And Rat

Xenogeneic bone marrow transplantation(XBMT) may will be a practicable treatment to some severe specific disease,such as AIDS,hepatitis and so on. The object of this experiment is to prevent graft versus host disease(GVHD) in XBMT.The experiment includes two procedure. First,SD rats were conditioned with 5.5Gy sublethal total body irradiation(TBI),followed by infusion of BALB/c mice bone marrow cells 8x107 on day 0,then were intraperitonially administered cyclophosphamide (CP) 150mg/Kg on day 2. The procedure let SD rats become chimerism and have specific immunologic tolerance. Second,BALB/c mice were conditioned with 9.0Gy lethal TBI and divided into two groups randomly. Group A were injected with bone marrow cells 4x107 and speen cells 2107 from chimeric rats,and group B injected with bone marrow cells 4xl07 and speen cells 2xl07 from normal rats. Observe GVHD for 60 days.The results showed that mouse lymphoid cells were present in the SD rats detected by fluorescence activated cell sorter(FACS) for morn than 90 days. The chimeric rates were 18%-45%,7%-23%,2%-8% on day 30,60,90 respectively. Thirty days after BMT,immunologic tolerance were evaluated by using skin grafting. The recipients of group A and B were normal rats,the donors were BALB/c and C57BL/6 mice respectively. The recipients of group C and D were chimeric rats,and the donors were BALB/c and C57BL/6 mice respectively. Skin surviving time of group A,B,C,D were 11.00+2.45 days,10.60 + 3.21 days,>90 days and 14.20 + 3.83 days. The differences within group A,B and D were not significant(P>0.05),but the differences were significant when compared group C to other groups(P<0.01). Forty-five days after BMT,the response of chimeric rats spleen cells to BALB/c mice spleen cells were mild,the value of4SI(Stimulating index) was 1.15 + 0.18;but the response to C57BL/6 mice spleen cells was still violent,the value of SI was 2.84 + 0.26. The differences were significant between the two groups. The response of normal rats and only TBI conditioned rats spleen cells to BALB/c and C57BL/6 mice spleen cells were all violent,the values of SI were 2.22 + 0.26,2.28+0.27,2.30 + 0.15,2.18 +0.31. The differences between these groups were not significant(P>0.05). These data showed that the chimerism were specially tolerant to donor xenoantigens in skin grafting and mixed lymphocyte reaction(MLR) assays,however were still immunocompetent to MHC-disparate third party C57BL/6 mouse. In the second experiment,mice of group B appeared with variant degree of wasting,diarrhea,fur losing,and all died within 15 days. Pathologic changes of liver and intestine were inflamming cells infiltrating and necrotizing. Mice of group B mostly survived for more than 60 days,except two mice died on day 18,31 respective. Surviving time of group A compared with group B was significant.Our conclusion is that using chimric donors can prevent GVHD in xenogeneic bone marrow transplantation.