Induction Of Accommodation In ABO-incompatible Renal Transplantation In Non-human Primates

At present, the worldwide shortage of allografts is one of the biggset barriers that circumscribe the progress and development of transplantation. The attempt of using the marginal grafts,xenogeneic grafts,and living donor grafts seems to be the promising way to cross this barrier. Using the living donor grafts often confronts the situation that the recipients carry the preformed antibodies include the ABO blood group antibody and HLA-specific antibody which may lead to hyperacute rejection and rapid graft loss after transplantation. The present desensitization therapy based on plasmapheresis and IVIg is costly, complicated, and sometimes has no certain therapeutic effects. Since the complement is the critical factor which mediates humoral rejection, it's theoretically valid to blockade the complement activation pathway in the purpose of inhibitting the hyperacute rejection after ABO-incompatible or HLA-presensitized transplatation. In this study, we tried to establish a ABO-incompatible renal allotransplant model in non-human primates, and used the complement inhibition-based strategy to induce long-term survival and the "accommodation" statement in renal allografts.In our previous study, the strategy of depleting the complement C3 by Y-CVF, can successfully induce the statement of "accommodation" in renal allotransplant model in donor skin-presensitized non-human primates. In order to clarify the correlation between the complement inhibition and the secondary immune response displayed by the production of de novo antibodies, we performed the following study. Recipient rhesus monkeys were presensitized by skin grafts from ABO-compatible donor monkeys to induce the production of the donor specific antibodies. Then the recipient subsequently received a kidney from the same donor 14 days later. The de novo antibodies as a output of the secondary immune response, has erupted to a high level in the early period after renal transplantation. These newly generated antibodies mediated the acute humoral rejection(AMR) in 3～4 days, which could not be reversed by the administration of CsA+MMF+Prednisone. In the experimental group, the additionally using Y-CVF in the early postoperative period led to very dramatic fall in serum C3 level, which allowed the long-term survival of the renal grafts. The de novo antibodies were not noticeable produced in this group. We concluded that the strategy of removing the complement by Y-CVF can effectively prevent the AMR of the presensitized renal transplantation through the mechanism correlated with the inhibition of secondary immune response.To study the accommodation in ABO-incompatible renal transplantation in non-human primates, we have to firstly establish a model that can precisely duplicate the progress and appearance of hyperacute rejection in the clinical ABO-incompatible renal transplantation. The ABO blood group system in monkeys is different from human:In monkeys, the circulating blood group antibody is lower in both level and efficacy, and the expression of ABO antigens is mainly on tissues, not on the red blood cells. In non-presensitized control group with the treatment of traditional CsA triple therapy, a ABO-incompatible renal allograft survived for 35 days without obvious rejection. This result suggested that the natural blood group antibodies in non-human primates were not adequate to mediateto the humoral rejection in ABO-incompatible renal transplantation. The keyhole limpet hemocyanin couple with A antigen (KLH-A) is a high-performance immunologic stimulant which can stimulate the production of anti-A IgM antibody in the B blood group recipients, After the presentization with KLH-A, blood group B recipient monkeys rapidly rejected the renal allografts from blood group A donors in 30 minutes after the reperfusion due to the hyperacute rejection. The strategy of KLH-A presensitization allows the establishment of the ABO-incompatible renal transplantation model in non-human primates.After the establishment of the hyperacute rejection model, we tried to use the Y-CVF in the early postoperative period combined with the maintenance therapy of CsA+MMF+Prednisone in the experiment group. All the grafts of 7 recipients were not hyperacutely rejected during the operation. Four of 7 recipients which had been hyper-presensitized by KLH-A, had their grafts developed acute humoral rejection (AHR) within 6 days after transplatation. The other 3 recipients have been presensitized temperately by KLH-A, none of them developed AHR with the Y-CVF therapy. Among them, one died from the drug-relative acute liver function failure, the other two survived more than 30 days without obvious rejection. In the mechanism study, the deposition of antibody but not C3 and C5b-9, has been detected on the endothelium of the graft even after the stop of Y-CVF and the return of circulating C3. The expression of CD55, CD59, CD46, and HO-1 were significantly elevated at different time-points in the long-term survival grafts via analysis of western blot, which prompted that the up-regulation of these protective proteins in the grafts may be associated with the establishment of accommodation,In conclusion, we have established the hypercute rejection model of ABO-incompatible renal transplantation in non-human primates, and expounded the characteristic of immunology and pathology of this model. By using short-term complement inhibition-based strategy, the hyperactue rejection was successfully prevented and "accommodation" could be induced in some of the renal grafts. The possible mechanism of the accommodation may be associated with the up-regulation of intragraft CD55, CD59, CD46, and HO-1.