Praeoperative Donor-spezifische Transfusionen kombiniert mit Cyclosporin induzieren Toleranz für MHC-l-inkompatible Herztransplantate im Miniatur Schwein Modell

Abstract

Purpose: To evaluate the effect of pre-transplant donor-specific transfusion on sensitization and tolerance induction to cardiac allografts in a clinically relevant large-animal model. Methods: Heterotopic cardiac transplants were performed across a major histocompatibility complex (MHC) class I barrier in inbred miniature swine. Experimental animals were treated with two donor-specific transfusions (DSTs), each containing 1.4×l08 viable peripheral blood mononuclear cells, 14 and 7 days prior to heart transplantation. All animals received a 12-day course of cyclosporine (CyA) (13 mg/kg IV) starting on post-operative day (POD) 0. Control groups received CyA alone, DST alone or no treatment. Cell mediated lympholysis (CML) assays were performed at regular basis. T cell priming and activation induced cell death (AICD) were assessed by carboxyfluoroscein succinimidyl ester (CFSE) proliferation assays and Annexin V staining. Rejection was monitored by serial biopsies. Results: Untreated (n = 2) and DST-only (n = 2) treated control animals rejected between POD 6 and 8. Animals treated with CyA alone (n = 3) exhibited graft survival to 53, 52 and 59 days. In contrast, the combination of DST-preteatment and CyA (n = 3) led to stable graft function for > 200, > 200, and > 200 days. Grafts in both the control and experimental groups showed equally severe cellular infiltrates on POD 28 and 50 (ISHLT lb to 3b/4). However, in the control groups, rejection continued to worsen over time, whereas in the experimental group, the cellular infiltrate diminished over time (ISHLT 0/4 on POD 100 and 200). Like the controls, experimental animals maintained peripheral CML response against donor and third party antigen. Following two DSTs, CD4+and CD8+recipient T cells demonstrated an increased donor-specific proliferative response on CFSE assay (CD4 +: 29.9% anti-donor, 16.4% anti-third-party; CD8 +: 45.9% anti-donor, 31.5% anti-third-party; n = 6). There was no difference in the rate of dividing T cells undergoing AICD in response to donor versus third-party antigen stimulation by Annexin V staining. None of the animals developed anti-donor antibodies following DST treatment. Conclusion: The combination of pre-transplant DST and a short course of CyA appears to facilitate tolerance to MHC class I disparate cardiac allografts in a preclinical miniature swine model. The sustained peripheral anti-donor CML response and the fact that alloreactive T cells were primed by the DST prior to transplantation suggest an active regulatory mechanism rather than peripheral deletion.