title: Beneficial effects of pretransplantation microchimerism on rejection-free survival in HLA-haploidentical family donor renal transplantation.
abstract: BACKGROUND
  Fetal-maternal microchimerism (MC) can develop during pregnancy and may persist for decades. Pretransplantation fetal-maternal MC may be present between mother and child and between siblings; however, its effect on renal transplantation is not known. We investigated the effects of pretransplantation MC on allograft outcomes in human leukocyte antigen (HLA)-haploidentical family donor transplantation.
  
  
  METHODS
  A total of 106 cases transplanted from 1996 to 2004 were retrospectively studied, with median follow-up of 96 months. The study and control groups included 63 and 43 cases of HLA-haploidentical and HLA-identical donor transplantations, respectively. MC against mismatched donor HLA-DRB1 allele was detected in the recipient's peripheral blood using nested polymerase chain reaction-single-strand conformation polymorphism method. The allograft outcomes of HLA-haploidentical MC (+) and (-) subgroups were compared with those of HLA-identical group.
  
  
  RESULTS
  Pretransplantation MC in the HLA-haploidentical recipients was detected in 22.2% (14 of 63). Compared with HLA-identical group, MC (-) subgroup showed significantly inferior allograft outcomes: higher acute rejection rate (11.6% vs. 42.9%; P=0.001), higher 5-year serum creatinine level (1.1 vs. 1.4 mg/dL; P=0.009), and lower 10-year rejection-free survival rate (83.7% vs. 54.5%; log-rank P=0.001). In contrast, MC (+) subgroup showed no significant differences from HLA-identical group in acute rejection rate (14.3%), 5-year serum creatinine level (1.1 mg/dL), and 10-year rejection-free survival rate (85.7%). Multivariate analysis revealed that pretransplantation MC is associated with a significantly lower risk of acute rejection (odds ratio=0.10; P=0.021).
  
  
  CONCLUSIONS
  Pretransplantation MC present in the recipient may have beneficial effects on rejection-free allograft survival in renal transplantation.
authors.affiliation: Department of Laboratory Medicine, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Shin Young
authors.initials: SY
authors.lastname: Joo
authors.forename: Eun Young
authors.initials: EY
authors.lastname: Song
authors.forename: Yunsu
authors.initials: Y
authors.lastname: Shin
authors.forename: Jongwon
authors.initials: J
authors.lastname: Ha
authors.forename: Sang Joon
authors.initials: SJ
authors.lastname: Kim
authors.forename: Myoung Hee
authors.initials: MH
authors.lastname: Park
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D046528:Chimerism; D005260:Female; D005500:Follow-Up Studies; D006084:Graft Rejection / Q000453:epidemiology*; D006085:Graft Survival / Q000502:physiology*; D006680:HLA Antigens / Q000235:genetics*; D059811:HLA-DRB1 Chains / Q000235:genetics; D006238:Haploidy; D006801:Humans; D007223:Infant; D053208:Kaplan-Meier Estimate; D016030:Kidney Transplantation / Q000401:mortality / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D057234:Preoperative Period; D012189:Retrospective Studies; D012307:Risk Factors; D014184:Transplantation, Homologous; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D006680:HLA Antigens; D059811:HLA-DRB1 Chains