title: Induction of Major Histocompatibility Complex-mismatched Mouse Lung Allograft Acceptance With Combined Donor Bone Marrow: Lung Transplant Using a 12-Hour Nonmyeloablative Conditioning Regimen.
abstract: BACKGROUND
  Despite broad and intense conventional immunosuppression, long-term survival after lung transplantation lags behind that for other solid organ transplants, primarily because of allograft rejection. Therefore, new strategies to promote lung allograft acceptance are urgently needed. The purpose of the present study was to induce allograft tolerance with a protocol compatible with deceased donor organ utilization.
  
  
  METHODS
  Using the major histocompatibility complex-mismatched mouse orthotopic lung transplant model, we investigated a conditioning regimen consisting of pretransplant T cell depletion, low-dose total body irradiation and posttransplant (donor) bone marrow, and splenocyte infusion followed by posttransplantation cyclophosphamide.
  
  
  RESULTS
  Our results show that C57BL/6 recipients of BALB/c lung allografts undergoing this complete short-duration nonmyeloablative conditioning regimen had durable lung allograft acceptance. Mice that lacked 1 or more components of this regimen exhibited significant graft loss. Mechanistically, animals with lung allograft acceptance had established higher levels of donor chimerism, lymphocyte responses which were attenuated to donor antigens but maintained to third-party antigens, and clonal deletion of donor-reactive host Vβ T cells. Frequencies of Foxp3 T regulatory cells were comparable in both surviving and rejected allografts implying that their perturbation was not a dominant cell-regulatory mechanism. Donor chimerism was indispensable for sustained tolerance, as evidenced by acute rejection of allografts in established chimeric recipients of posttransplantation cyclophosphamide after a chimerism-ablating secondary recipient lymphocyte infusion.
  
  
  CONCLUSIONS
  Together, these data provide proof-of-concept for establishing lung allograft tolerance with tandem donor bone marrow transplantation using a short-duration nonmyeloablative conditioning regimen and posttransplant cyclophosphamide.
authors.affiliation: Department of Anesthesiology, Johns Hopkins University School of Medicine, Baltimore, MD.
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Dodd-O
authors.affiliation: Division of Hematologic Malignances, Johns Hopkins Sidney Kimmel Comprehensive Cancer Center, Baltimore, MD.
authors.forename: Sudipto
authors.initials: S
authors.lastname: Ganguly
authors.affiliation: Division of Hematologic Malignances, Johns Hopkins Sidney Kimmel Comprehensive Cancer Center, Baltimore, MD.
authors.forename: Ante
authors.initials: A
authors.lastname: Vulic
authors.affiliation: University of Minnesota Cancer Center and Department of Pediatrics, Division of Blood and Marrow Transplantation, Minneapolis, MN.
authors.forename: Angela
authors.initials: A
authors.lastname: Panoskaltsis-Mortari
authors.affiliation: Division of Pulmonary, Allergy and Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15213.
authors.forename: John F
authors.initials: JF
authors.lastname: McDyer
authors.affiliation: Division of Hematologic Malignances, Johns Hopkins Sidney Kimmel Comprehensive Cancer Center, Baltimore, MD.
authors.forename: Leo
authors.initials: L
authors.lastname: Luznik
mesh_terms: D064591:Allografts; D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology*; D016026:Bone Marrow Transplantation; D003520:Cyclophosphamide / Q000494:pharmacology; D051858:Forkhead Transcription Factors / Q000378:metabolism; D006084:Graft Rejection / Q000276:immunology; D006085:Graft Survival; D006086:Graft vs Host Disease; D007108:Immune Tolerance / Q000187:drug effects; D016040:Lung Transplantation / Q000379:methods*; D008212:Lymphocyte Depletion; D008214:Lymphocytes / Q000166:cytology; D008285:Major Histocompatibility Complex / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D013601:T-Lymphocytes / Q000166:cytology; D013997:Time Factors; D018183:Transplantation Chimera / Q000276:immunology; D019172:Transplantation Conditioning / Q000379:methods*; D023001:Transplantation Tolerance; D014184:Transplantation, Homologous
chemical_list: D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse; D003520:Cyclophosphamide