title: Incidence of positive C4d deposition in long-term survival cases over 10 yr after renal transplantation.
abstract: BACKGROUND
  The incidence of positive C4d deposition in peritubular capillaries (PTC) in long-term survival cases remains controversial. Some incidences of positive C4d deposition in PTC in cases of long-term survival less than 10 yr have been reported. We retrospectively examined the incidence of positive C4d deposition in long-term survival cases over 10 yr after renal transplantation and the histological and clinical characteristics of the positive C4d staining cases.
  
  
  METHODS
  We examined 14 protocol biopsy cases performed at Osaka University Hospital between March 2004 and March 2005. The average interval between the operation and the day of biopsy was 15.4 yr. Histological diagnosis was made in accordance with the Banff 97 classification. Paraffin-embedded tissue was stained with polyclonal anti-C4d antibody. Detection of donor-specific antibody (DSA) was determined by flow cytometric assay. The cases were divided according to C4d positivity.
  
  
  RESULTS
  Three of 14 cases (21.4%) were C4d positive and belonged to the C4d+/DSA+ group, while 11 cases were of the C4d-/DSA- group. There were no significant differences between the two groups in serum creatinine (sCr) or proteinuria at the time of biopsy. A trend towards decreasing rate of the inverse of sCr (1/sCr) in the C4d+/DSA+ group was noted. In the C4d+/DSA+ group, three transplant glomerulopathy (TGP) were identified. On the other hand, TGP were identified in six of 11 cases of the C4d-/DSA- group. We investigated the relevance of typical chronic rejection (CR) features and the positivity of C4d. No significant differences were observed between the CR features and C4d depositions in PTC (p = 0.26).
  
  
  CONCLUSIONS
  In long-term survival cases with positive C4d, a trend towards decreasing rate of 1/sCr was revealed, but their histological characteristic features was not recognized.
authors.affiliation: Department of Urology, Graduate School of Medicine, Osaka University, Osaka, Japan.
authors.forename: Yukiomi
authors.initials: Y
authors.lastname: Namba
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Oka
authors.forename: Toshiki
authors.initials: T
authors.lastname: Moriyama
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kyo
authors.forename: Ryoichi
authors.initials: R
authors.lastname: Imamura
authors.forename: Yi
authors.initials: Y
authors.lastname: Shi
authors.forename: Naotsugu
authors.initials: N
authors.lastname: Ichimaru
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Isaka
authors.forename: Shiro
authors.initials: S
authors.lastname: Takahara
authors.forename: Akihiko
authors.initials: A
authors.lastname: Okuyama
mesh_terms: D000328:Adult; D001706:Biopsy; D003181:Complement C4 / Q000378:metabolism*; D005260:Female; D005500:Follow-Up Studies; D006085:Graft Survival / Q000502:physiology*; D006801:Humans; D007150:Immunohistochemistry; D007668:Kidney / Q000737:chemistry / Q000276:immunology*; D016030:Kidney Transplantation / Q000276:immunology*; D008297:Male; D012189:Retrospective Studies
chemical_list: D003181:Complement C4