title: Durable engraftment of major histocompatibility complex-incompatible cells after nonmyeloablative conditioning with fludarabine, low-dose total body irradiation, and posttransplantation cyclophosphamide.
abstract: Treatment of leukemia by myeloablative conditioning and transplantation of major histocompatibility complex (MHC)-mismatched stem cells is generally avoided because of the high risk of graft rejection or lethal graft-versus-host disease (GVHD). This study shows that MHC-incompatible cells can engraft stably after nonmyeloablative conditioning with immunosuppressive chemotherapy and low-dose total body irradiation (TBI). Long-term mixed hematopoietic chimerism, clonal deletion of donor-reactive T cells, and bidirectional cytotoxic T-cell tolerance were achieved by transplanting MHC-mismatched marrow cells into recipients conditioned with pretransplantation fludarabine or cyclophosphamide (Cy), 50 to 200 cGy TBI on day -1, and Cy 200 mg/kg intraperitoneally on day 3. In this model, long-term donor chimerism was proportional to the dose of TBI or donor marrow cells. Pretransplantation fludarabine and posttransplantation Cy were both required for alloengraftment, but the drugs had additional effects. For example, fludarabine sensitized host stem cells to the toxicity of TBI, because animals conditioned with both agents had higher chimerism than animals conditioned with TBI alone (P <.05). Also, posttransplantation Cy attenuated lethal and nonlethal GVH reactions, because F(1) recipients of host-reactive, parental spleen cells survived longer (P <.05) and had lower donor cell chimerism (P <.01) if they received posttransplantation Cy than if they did not. Finally, delayed infusions of donor lymphocytes into mixed chimeras prolonged survival after leukemia challenge (P <.0001) without causing lethal GVHD. These results indicate that stable engraftment of MHC-incompatible cells can be induced after fludarabine-based, nonmyeloablative conditioning and that it serves as a platform for adoptive immunotherapy with donor lymphocyte infusions.
authors.affiliation: Division of Hematopoiesis, Hematologic Malignancies, and Pediatric Oncology, Johns Hopkins Oncology Center, Baltimore, MD, USA.
authors.forename: L
authors.initials: L
authors.lastname: Luznik
authors.forename: S
authors.initials: S
authors.lastname: Jalla
authors.forename: L W
authors.initials: LW
authors.lastname: Engstrom
authors.forename: R
authors.initials: R
authors.lastname: Iannone
authors.forename: E J
authors.initials: EJ
authors.lastname: Fuchs
mesh_terms: D000818:Animals; D003520:Cyclophosphamide / Q000627:therapeutic use*; D006085:Graft Survival; D006086:Graft vs Host Disease / Q000517:prevention & control; D020544:Graft vs Leukemia Effect; D018380:Hematopoietic Stem Cell Transplantation; D006648:Histocompatibility; D007166:Immunosuppressive Agents / Q000627:therapeutic use*; D051379:Mice; D008806:Mice, Inbred AKR; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D018183:Transplantation Chimera; D019172:Transplantation Conditioning; D014740:Vidarabine / Q000008:administration & dosage* / Q000031:analogs & derivatives*; D014916:Whole-Body Irradiation
chemical_list: D007166:Immunosuppressive Agents; D003520:Cyclophosphamide; D014740:Vidarabine; C024352:fludarabine