title: Acute renal allograft rejection: diagnostic significance of focal peritubular capillary C4d.
abstract: BACKGROUND
  Focal PTC C4d staining in acute renal allograft rejection has not been studied extensively.
  
  
  METHODS
  Renal allograft biopsies performed after October 2003, representing the first episode of acute rejection (AR) in recipients with > or = 12 months follow-up postbiopsy, were assessed for extent of C4d and correlated with morphology, ELISA screen, donor-specific antibodies (DSA), response to treatment, and outcome.
  
  
  RESULTS
  In 106 biopsies (16 C4d-diffuse; 24 C4d-focal; 66 C4d-negative), there were no differences among the three groups in terms of timing or grade of AR, creatinine level, tacrolimus level, and grade of interstitial fibrosis/tubular atrophy or graft loss. The C4d-diffuse group was significantly associated with less tubulitis (P=0.0021), and more chronic allograft arteriopathy (P=0.0527). Incomplete response to steroid therapy was more frequent in C4d-diffuse/focal compared with negative cases (P=0.0492). DSA frequency within 1 year of AR was highest in the C4d-diffuse (94%), followed by C4d-focal (38%), and C4d-negative (17%) groups (P<0.0001).
  
  
  CONCLUSIONS
  Focal PTC C4d was associated with circulating antibodies, with a 2-fold greater diagnostic sensitivity than negative C4d staining. The finding of diffuse C4d on follow-up biopsy was significantly associated with graft loss at 1 year, regardless of index biopsy C4d results.
authors: Department of Surgery, University of Florida Medical Center, Gainesville, FL 32610-0286, USA. liisekayler@yahoo.com
authors: Liise K
authors: LK
authors: Kayler
authors: Lawrence
authors: L
authors: Kiss
authors: Vivek
authors: V
authors: Sharma
authors: Ravi
authors: R
authors: Mohanka
authors: Adriana
authors: A
authors: Zeevi
authors: Alin
authors: A
authors: Girnita
authors: Ron
authors: R
authors: Shapiro
authors: Parmjeet S
authors: PS
authors: Randhawa
mesh_terms: D002196:Capillaries / Q000473:pathology; D015935:Complement C4b / Q000032:analysis*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006084:Graft Rejection / Q000175:diagnosis* / Q000276:immunology / Q000473:pathology; D006085:Graft Survival / Q000276:immunology; D006650:Histocompatibility Testing; D006801:Humans; D016030:Kidney Transplantation / Q000473:pathology*; D007684:Kidney Tubules / Q000098:blood supply*; D008297:Male; D008875:Middle Aged; D016035:Pancreas Transplantation / Q000473:pathology; D010446:Peptide Fragments / Q000032:analysis*
chemical_list: D010446:Peptide Fragments; D015935:Complement C4b; C032261:complement C4d