The Successful Induction of Systemic Tolerance to a Class-I MHC Disparity through Adoptive Transfer in a Large Animal Model

Abstract

Background: We have previously reported that 12 days of high dose CyA uniformly leads to tolerance of MHC class I-mismatched renal grafts in MHC inbred miniature swine. We have now attempted to induce tolerance in secondary recipients by the adoptive transfer of a long-term tolerant kidney with or without tolerated cells. Methods: (1) Adoptive Transfer Donors: Three MHC inbred SLAdd miniature swine received life-supporting MHC class I-mismatched kidneys (SLAgg) with 12 days of high dose CyA to induce tolerance. Three to four months after kidney transplant (KTx) these animals received a Donor Specific Transfusion (DST) to expand T regulatory cells. (2) Adoptive Transfer Recipients: Three recipients, MHC-matched to the adoptive transfer donors (SLAdd), received 150 rad whole body irradiation (WBI) one day before receiving class I mismatched kidneys from the donors. Two of these animals also received 4-5 × 10ˆ9 cells/kg cells, obtained by leukapheresis from the adoptive transfer donors, on day -1. Tolerated kidneys (SLAgg) were transplanted (day 0) without further immunosuppression. Second donor matched kidneys from naïve SLAgg animals were transplanted >100 days later to confirm tolerance. (3) Controls: Three SLAdd animals received 150 rad WBI on day -1 followed by a class I MHC mismatched KTx. (4) Graft function was assessed by serum creatinine and histology. Immunologic responses were assessed by Cell Mediated Lysis (CML) assays. Anti-Donor MHC antibody was assessed by FACS. Results: The three controls rejected the naïve Class I mismatched kidney by day 9. All three recipients accepted tolerated kidneys >100 days and did not reject second donor matched naïve kidneys transplanted without immunosuppression, confirming systemic tolerance. All three animals maintained donor specific unresponsiveness by cellular assays and two animals did not develop antibody to donor. Conclusions: To our knowledge, these results provide the first evidence for the successful transfer of systemic tolerance in a large animal model by the adoptive transfer of tolerated kidneys into 150-rad irradiated miniature swine.