title: [Experimental study on rejection of allogeneic donor bone marrow cells in sensitized recipients].
abstract: OBJECTIVE
  To establish a murine model of sensitization, and investigate the effect and mechanism of sensitization on allogeneic donor bone marrow cells (BMCs).
  
  
  METHODS
  Sensitized BALB/c mice were established by transfusions of allogeneic splenocytes. The donor reactive antibodies were detected by binding and complement-dependent cytotoxicity assays. After irradiation, 1 × 10(7) BMCs of C57BL/6 donor mice were injected into non-sensitized or sensitized BALB/c recipient mice. The distribution pattern of donor BMCs in peripheral blood, spleen and bone marrow of recipient mice were analyzed at different time points (2 h, 12 h and 48 h) post transplantation. Hematopoietic recovery post transplantation was assessed, and survival was monitored. Moreover, sera and splenocytes derived from non-sensitized or sensitized recipients were incubated with allogeneic BMCs in vitro, and the cytotoxic indexes were calculated in the immune experiments.
  
  
  RESULTS
  The binding and complement-dependent cytotoxicity assays showed that a high level of donor reactive antibodies was presented in sensitized sera. Compared with the non-sensitized recipients, the homing assay showed significantly decreased distributions of allogeneic donor BMCs in peripheral blood, spleen and femur of sensitized recipients. Non-sensitized recipients survived long term after irradiation, while all the sensitized recipients died within 12-15 days. Fourteen days post transplantation, the white blood cells and BMCs of non-sensitized recipients were (3240 ± 300) × 10(6)/L and (396 ± 27) × 10(6)/femur, respectively; while the white blood cells and BMCs of sensitized recipients were (320 ± 80) × 10(6)/L and (6 ± 2) × 10(6)/femur, respectively; the differences were statistically significant between this two groups (P < 0.05). Seven days post transplantation, the percentage of donor cells in bone marrow of non-sensitized and sensitized recipients was (48.07 ± 4.70)% and (0.77 ± 0.11)%, respectively, and the differences were statistically significant (P < 0.05). Furthermore, the white blood cells and BMCs following transplantation decreased along with time in sensitized recipients. The immune experiments of complement-dependent cytotoxicity reaction, cytotoxic T lymphocytes reaction and antibody-dependent cellular cytotoxicity showed the cytotoxic indexes were higher in sensitized group than the non-sensitized group.
  
  
  CONCLUSIONS
  A sensitized model was established by transfusions of allogeneic spleen cells. Allogeneic donor BMCs were rejected in sensitized recipients, and its mechanism might be through immune impairment pathways.
authors.affiliation: Department of Pediatrics, Zhongshan University, Guangzhou, China.
authors.forename: Lü-hong
authors.initials: LH
authors.lastname: Xu
authors.forename: Jian-pei
authors.initials: JP
authors.lastname: Fang
authors.forename: Wen-jun
authors.initials: WJ
authors.lastname: Weng
authors.forename: Hong-gui
authors.initials: HG
authors.lastname: Xu
authors.forename: Qi-xiang
authors.initials: QX
authors.lastname: Ye
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells; D016026:Bone Marrow Transplantation; D004195:Disease Models, Animal; D006084:Graft Rejection; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D014019:Tissue Donors; D014184:Transplantation, Homologous