Prolongation Of Cardiac Allograft Survival By Depletion Of Complement Using Y-CVF In Presensitized Rat

Objective Study the effects of Y-CVF on depleting complement in vivo and prolonging allograft survival in acute humoral rejection rat cardiac allograft rejection model. Methods Allograft Lewis rats were presensitized by sequential grafting of three full-thickness Brown-Norway rats skin grafts. Then presensitized Lewis rats received a heterotopic Brown-Norway cardiac allograft. Serum elicit cytotoxic alloantibody titers of Lewis rat were determined by a modified in vitro complement-dependent microcytotoxicity assay. Fifteen recipient rats were randomly divided into control group: rats untreated (n=7) and test group: rats was administered by i.v. injection with a single dose of 0.08 mg/kg CVF (n=8) on day -1. Anticomplementary activity of the Y-CVF in vivo was measured by CH50. As cessation of graftbeat, allograft rejection was confirmed by tissue pathology and immunohistochemistry examination. Results After presensitized serum elicit cytotoxicantibody titer of Lewis rats raised prominently from 0 to 1∶1 028~1∶2056. A single dose of Y-CVF (0.08mg/kg) eliminated complement activity to an undetectable level 24 h after administration. The survival time of graft was significantly prolonged to 99.50±38.72 h in rats received CVF, compared with a rejection time of 12.71±13.94 h in untreated rats (t=5.599, P <0.001). Histology of rejected allografts from untreated group animals generally revealed the features of acute humoral rejection, including intravascular thrombosis, myocardial necrosis, interstitial hemorrhage and edema,intense infiltration that were primary composed of granulocytes. The allografts rejected in CVF treated rats demonstrated histopathologic feature of acute rejection with extensive cellular infiltration with mononuclear cells, myocardial necrosis. Immunohistochemistry demonstrated deposition of IgG in treatment group as well as in control group. Deposition of C3 was only found in control group. Conclusion Our study demonstrated administration of CVF can overcome acute humoral rejection in models of presensitized rat cardiac allotransplantation. Y-CVF showed potentially capacity to use in clinical transplantation across ABO incompatible and positive cross-match barriers.