Incidence of positive C4d deposition in long-term survival cases over 10 yr after renal transplantation.
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.
Namba
Yukiomi
Y
Department of Urology, Graduate School of Medicine, Osaka University, Osaka, Japan.
Oka
Kazumasa
K
Moriyama
Toshiki
T
Kyo
Masahiro
M
Imamura
Ryoichi
R
Shi
Yi
Y
Ichimaru
Naotsugu
N
Isaka
Yoshitaka
Y
Takahara
Shiro
S
Okuyama
Akihiko
A
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
D003181:Complement C4