The Journal of Heart and Lung Transplantation Volume 21, Number 1 Procedure: Animals received combined heterotopic heart and kidney transplants from the same donors across a class I mismatch, and were treated with 12 days of high-dose CyA. Animals underwent total thymectomy at least 100 days after initial transplantation and were compared to non-thymectomized controls. Open myocardial biopsies and assays of cell mediated lympholysis (CML) were performed at regular intervals. Results: Non-thymectomized heart/kidney transplant recipients developed stable and long-term tolerance with donor-specific unresponsiveness on CML assays and no evidence of CAV in biopsies. In contrast, thymectomized recipients developed significant (grade3/3) CAV lesions while CML assays remained unresponsive. Preliminary studies using magnetic-bead cell-sorting revealed that CD4⫹CD25⫹ cells separated from PBMC drawn from these tolerant heart/kidney recipients suppressed the response of naive recipient-matched PBMC against donor-type cells, and depletion of this population led to loss of this inhibition. Conclusions: The presence of both the kidney and thymus were necessary for maintenance of tolerance to the heart in this model. A CD4⫹CD25⫹ regulatory cell, which traffics between the kidney and the thymus, may explain these results. 67 COMBINED BONE MARROW AND LUNG TRANSPLANTATION OVER MAJOR HISTOCOMPATIBILITY BARRIERS IN MINIATURE SWINE G. Warnecke,1 M. Strueber,1 S.P. Sommer,1 M. Avsar,1 M. Morancho,1 J. Niedermeyer,2 J.M. Hohlfeld,2 A.R. Simon,1 J.H. Karstens,3 A. Haverich,1 1Thoracic and Cardiovascular Surgery, Hannover Medical School, Hannover, Germany; 2Respiratory Medicine, Hannover Medical School, Hannover, Germany; 3 Radiation Oncology, Hannover Medical School, Hannover, Germany Purpose: The purpose of this study was to evaluate a clinically feasible tolerance induction regimen including single-dose irradiation, donor bone marrow infusion and a 28-day course of pharmacologic immunosuppression in a porcine lung transplantation model. Methods: Left-sided single lung transplantation from MHC class I and II mismatched donors was performed in 6 minipips after recipient whole body (1.5 Gy) and selective thymic irradiation (7 Gy). Donor bone marrow was isolated by gradient centrifugation, cultured for 24 h and infused on POD 1 at 5x107 cells/kg (BMTX). Immunosuppression included 1.5 mg/kg/d methylprednisolone and cyclosporine A (serum levels ⬎300 ng/ml). Five animals served as controls without irradiation and received triple immunosuppression additionally including 1.0 mg/kg/d azathioprin. Immunosuppressive drugs were discontinued in all animals on postoperative day (POD) 28. Multi-lineage donor cell chimerism was monitored by flow cytometry. Donor-specific tolerance was tested in vitro by mixed lymphocyte reaction (MLR). Results: Two BMTX animals were lost to thrombocytopenic complications on POD 9 and 10. The other animals showed good graft function without rejection on POD 28. Control animals rejected within 50 days after withdrawal of immunosuppression. One BMTX animal rejected on POD 62, one was sacrificed on POD 70 with endobronchial thrombosis due to thrombocytopenic bleeding, one showed in-vitro tolerance, however it was sacrificed on POD 265 due to severe GvHD and one animal showed early
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in vitro tolerance, but was sacrificed on POD 170 due to chronic graft bronchiolitis obliterans. Macrochimerism, detected by donor-specific SLA I mAb, was between 5 and 40% after lung transplantation and BMTX, but has been lost after POD 80. One animal, that eventually developed severe GvHD, revealed persistend macrochimerism. Conclusion: Despite successful bone marrow and lung transplantation, long term tolerance was not achieved. However, in this model lung allograft survival without immunosuppression was improved. 68 PASSENGER LEUKOCYTES FROM TRANSPLANTED HEARTS PRODUCE COMPLEMENT Z. Qian, J. Layton, J. Liu, B.A. Wasowska, W.M. Baldwin, III, Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD Sublytic amounts of membrane attack complex can modulate immune responses by activating antigen presenting cells, leukocytes and parenchymal cells. Because macrophages can produce all of the components of the classical pathway of complement in vitro, we asked whether “passenger” leukocytes from transplants could produce complement in recipients. Using C6 deficient inbred rat strains, we produced donors with C6 deficient hearts that bore C6 sufficient “passenger” leukocytes by irradiating C6 deficient PVG.1A (RT1a) rats and reconstituting them with syngeneic bone marrow from C6 positive rats. Control heart donors were reconstituted with C6 deficient bone marrow. After 8 weeks, low levels of C6 was present in the circulation of these C6 chimeric rats. Hearts were harvested from these C6 chimeric animals and transplanted to MHC mismatched C6 deficient PVG.1L (RT1l) recipients (n⫽6). Cardiac allograft recipients were sacrificed 4 or 7 days after transplantation and their tissues harvested for RT-PCR analysis. C6 mRNA transcripts were demonstrated in the transplanted heart, and also in tissues of the recipient, including peripheral blood, liver, spleen and lymph nodes. These results demonstrate that “passenger” leukocytes can produce C6 in the transplant and lymphoid tissues of the recipient. Production of complement by allogeneic cells may augment antigen recognition and stimulation of host lymphoid tissues. The potential relevance of local C6 production was demonstrated by the finding that C6 deficient PVG.1U recipients reject hearts from C6 sufficient PVG.1A donors (n⫽11) more rapidly than hearts from C6 deficient PVG.1A donors (n⫽11). In summary, “passenger” leukocytes may modify responses to transplant antigens by local complement production in the transplant and the lymphoid tissues of the recipient. 69 QUALITY OF LIFE IN FEMALE HEART TRANSPLANT CANDIDATES AND RECIPIENTS L.S. Evangelista,1 K. Dracup,2 L.V. Doering,1 J. Kobashigawa,3 M. Hamilton,3 G. Fonarow,3 1School of Nursing, University of California at Los Angeles, Los Angeles, CA; 2School of Nursing, University of California at San Francisco, San Francisco, CA; 3 School of Medicine, University of California at Los Angeles, Los Angeles, CA Previous research supports changes in quality of life (QOL) following heart transplantation. However, studies specifically designed to examine the experiences of women before and after heart transplantation are limited. This study was conducted to