[Study on the induction of xenogeneic tolerance of rat to mouse bone marrow transplantation].

OBJECTIVE: To establish an effective protocol for potential clinical usage in inducing donor-specific tolerance across xenogeneic barriers. METHODS: C57BL/6 (B6) mice were conditioned with 5 Gy sublethal total body irradiation (TBI), followed by infusion of 4 x 10(7) Lewis rat bone marrow cells on day 0, then were intraperitonially administered 150 mg/kg cyclophosphamide (CP) on day 2. Recipients were characterized for engraftment with xenogeneic bone marrow cells by using fluorescence activated cell sorter (FACS) to determine the percentage of rat origin cells in the peripheral blood lymphocytes(PBL), splenic and thymic lymphoid cells on day 30, 60 and 90. Mixed lymphocyte reaction (MLR) and delayed type hypersensitivity (DTH) assay were performed on day 30 to examine the tolerance status. RESULTS: Rat lymphoid chimeras were reliable present in the tolerant B6 mice for more than 3 months. B6 recipients were specifically tolerant to host xenoantigens in MLR and DTH assays, but were still immunocompetent to MHC-disparate third party BALB/c mouse or DA rat stimulator cells. CONCLUSION: A durable rat to mouse xenogeneic bone marrow transplantation tolerance was achieved in this modal.