title: The clinical and molecular significance of C4d staining patterns in renal allografts.
abstract: BACKGROUND
  We investigated the clinical and molecular significance of minimal peritubular capillary (PTC) and isolated glomerular C4d+ staining using microarrays.
  
  
  METHODS
  Two hundred fifty-five clinically indicated transplant biopsies were included in the analyses. C4d staining was performed on paraffin sections using a polyclonal rabbit anti-C4d antibody. Gene expression profiles in a subset of patients were studied using Affymetrix HuGene 1.0ST arrays.
  
  
  RESULTS
  Immunohistochemistry for C4d of 255 biopsies showed 51% C4d negative, 4% minimal PTC C4d+, 15% focal or diffuse PTC C4d+, and 31% isolated glomerular C4d+ biopsies. Patients with minimal and focal/diffuse PTC C4d+ staining had higher frequency of donor-specific anti-HLA antibodies (DSA) (67% and 82%) and antibody mediated rejection (AMR) (66% and 89%) when compared with C4d-negative biopsies (25% and 19%, respectively) (P<0.001). The glomerulitis, interstitial inflammation, and peritubular capillaritis scores were also significantly higher in minimal (0.88, 1.25, and 1.5) and focal/diffuse PTC C4d+ biopsies (0.65, 1.41, and 1.5), compared with C4d-negative biopsies (0.25, 079, and 0.34), respectively. There were no differences in the DSA frequency, AMR rate, or Banff scores between isolated glomerular C4d+ and C4d-negative patients. Although both minimal and focal/diffuse C4d+ biopsies showed increased expression of genes related to the immune response, interferon-gamma and rejection-induced, cytotoxic T cell and constitutive macrophage-associated pathogenesis-based transcripts, there was no activation of immune-response-related genes in isolated glomerular C4d+ biopsies.
  
  
  CONCLUSIONS
  Minimal PTC C4d+ staining but not isolated glomerular C4d+ staining is associated with AMR, circulating DSAs and immune-response-related gene activation.
authors.affiliation: Division of Pediatric Nephrology, Children's Hospital at Montefiore, Bronx, NY, USA.
authors.forename: Nicole
authors.initials: N
authors.lastname: Hayde
authors.forename: Yi
authors.initials: Y
authors.lastname: Bao
authors.forename: James
authors.initials: J
authors.lastname: Pullman
authors.forename: Bin
authors.initials: B
authors.lastname: Ye
authors.forename: Brent R
authors.initials: BR
authors.lastname: Calder
authors.forename: Monica
authors.initials: M
authors.lastname: Chung
authors.forename: Daniel
authors.initials: D
authors.lastname: Schwartz
authors.forename: Ahmed
authors.initials: A
authors.lastname: Alansari
authors.forename: Graciela
authors.initials: G
authors.lastname: de Boccardo
authors.forename: Min
authors.initials: M
authors.lastname: Ling
authors.forename: Enver
authors.initials: E
authors.lastname: Akalin
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000032:analysis*; D001706:Biopsy; D002196:Capillaries / Q000276:immunology / Q000473:pathology; D016009:Chi-Square Distribution; D015935:Complement C4b / Q000032:analysis* / Q000235:genetics; D005260:Female; D020869:Gene Expression Profiling / Q000379:methods; D005786:Gene Expression Regulation; D006084:Graft Rejection / Q000276:immunology / Q000473:pathology; D006680:HLA Antigens / Q000276:immunology; D006648:Histocompatibility; D006801:Humans; D007150:Immunohistochemistry; D007518:Isoantibodies / Q000097:blood; D053208:Kaplan-Meier Estimate; D007668:Kidney / Q000098:blood supply / Q000276:immunology* / Q000473:pathology / Q000601:surgery*; D007678:Kidney Glomerulus / Q000276:immunology / Q000473:pathology; D016030:Kidney Transplantation / Q000276:immunology* / Q000401:mortality; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D020411:Oligonucleotide Array Sequence Analysis; D010446:Peptide Fragments / Q000032:analysis* / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers; D006680:HLA Antigens; D007518:Isoantibodies; D010446:Peptide Fragments; D012333:RNA, Messenger; D015935:Complement C4b; C032261:complement C4d