Complement fragment C4d deposition in peritubular capillaries in acute humoral rejection after ABO blood group-incompatible human kidney transplantation.
BACKGROUND
Acute humoral rejection (AHR) is the most important risk factor for early graft loss in ABO-incompatible (ABO-i) kidney transplantation (RTx). The pathogenesis and diagnostic criteria for AHR after ABO-i RTx remain unclear. Complement fragment C4d deposition in peritubular capillaries (PTC), which is a sensitive indicator for activation of the classical complement pathway, was studied to establish the pathologic diagnostic indicator of AHR.


METHODS
Forty-four graft biopsy specimens from 19 patients with ABO-i living donors were analyzed within 90 days after RTx. Nineteen biopsy specimens with acute rejection after ABO-compatible (ABO-c) living-related RTx were used as controls. Diffuse and bright C4d deposition in PTC was considered significantly positive.


RESULTS
All of 8 recipients with AHR showed significantly positive C4d in PTC in the ABO-i group, but 9 of 11 recipients without AHR were negative. In the ABO-c RTx group, 16 of 19 recipients were negative for C4d in PTC. The prevalence of C4d in PTC was significantly higher in ABO-i RTx (P<0.05).


CONCLUSIONS
C4d deposition is valuable as a specific and sensitive indicator for AHR, even of mild severity, in ABO-i RTx.
Kato
Masako
M
The Third Department of Internal Medicine, Nagoya City University Medical School, Nagoya, Japan.
Morozumi
Kunio
K
Takeuchi
Oki
O
Oikawa
Tadashi
T
Koyama
Katsushi
K
Usami
Takeshi
T
Shimano
Yasunobu
Y
Ito
Akinori
A
Horike
Keiji
K
Otsuka
Yasuhiro
Y
Toda
Susumu
S
Takeda
Asami
A
Uchida
Kazuharu
K
Haba
Toshihito
T
Kimura
Genjiro
G
D000017:ABO Blood-Group System; D000208:Acute Disease; D001787:Blood Group Incompatibility; D002196:Capillaries / Q000378:metabolism; D003181:Complement C4 / Q000378:metabolism*; D015935:Complement C4b; D035061:Control Groups; D006084:Graft Rejection / Q000378:metabolism*; D006801:Humans; D016030:Kidney Transplantation / Q000276:immunology*; D007684:Kidney Tubules / Q000098:blood supply*; D010446:Peptide Fragments / Q000378:metabolism*
D000017:ABO Blood-Group System; D003181:Complement C4; D010446:Peptide Fragments; D015935:Complement C4b; C032261:complement C4d