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Updated: Apr 10, 2026
Mouse Kidney Transplantation: Models of Allograft Rejection
Published on: October 11, 2014
Capillary C4d and Kidney Allograft Outcome in Relation to Morphologic Lesions Suggestive of Antibody-Mediated
Željko Kikić1, Alexander Kainz2, Nicolas Kozakowski3
1Division of Nephrology and Dialysis, Department of Medicine III, Medical University Vienna, Vienna, Austria;
Insights
C4d staining, indicating complement activation, independently predicts worse kidney transplant outcomes and graft loss in antibody-mediated rejection (ABMR). This marker signifies a more severe form of ABMR.
Area of Science:
- Nephrology
- Transplantation Immunology
- Pathology
Background:
- Antibody-mediated rejection (ABMR) is a significant cause of kidney transplant failure.
- The role of C4d staining, a marker of complement activation, in predicting ABMR severity is debated.
- Complement activation is a key effector pathway in antibody-mediated graft injury.
Purpose of the Study:
- To investigate the independent clinical predictive value of capillary C4d staining in renal allograft recipients.
- To determine if C4d positivity indicates a more severe form of ABMR.
- To assess the association of C4d staining with long-term graft survival and renal function decline.
Main Methods:
- Retrospective analysis of 885 renal allograft recipients with indication biopsies.
- Reevaluation of 1976 biopsy specimens for capillary C4d staining and ABMR-specific morphologic lesions.
- Statistical analysis including Cox regression and mixed models to assess graft survival and eGFR decline.
Main Results:
- C4d-positive patients had significantly worse 8-year death-censored graft survival compared to C4d-negative patients (53-67% vs. 66-81%).
- C4d staining was independently associated with an increased risk of graft loss (HR 1.85, P<0.001), even with fewer than two ABMR lesions.
- C4d positivity independently predicted a steeper decline in estimated glomerular filtration rate (eGFR).
Conclusions:
- Intragraft complement activation, detected by C4d staining, is a valuable independent indicator of ABMR.
- C4d positivity is associated with adverse kidney transplant outcomes, including graft loss and accelerated loss of renal function.
- C4d staining identifies a particularly severe manifestation of ABMR.
Background And Objectives:
Recent studies highlighting a role of C4d- antibody-mediated rejection (ABMR) have debated whether C4d staining has independent value as a rejection marker. Considering the presumed role of complement as an important effector of graft injury, this study hypothesized that capillary C4d, a footprint of antibody-triggered complement activation, indicates a particularly severe manifestation of ABMR.
Design, Setting, Participants, & Measurements:
This large retrospective clinicopathologic study sought to assess the clinical predictive value of C4d staining in relation to ABMR morphology. Overall, 885 renal allograft recipients who underwent transplantation between 1999 and 2006 (median duration of follow-up, 63.3 [interquartile range, 40.6-93.5] months; 206 graft losses) were included if they had had one or more indication biopsies. A total of 1976 biopsy specimens were reevaluated for capillary C4d staining (C4d data were available for 825 patients) and distinct morphologic lesions suggestive of ABMR, including glomerulitis, peritubular capillaritis, capillary microthrombi, transplant glomerulopathy, and severe intimal arteritis.
Results:
C4d+ patients, with or without ABMR features, had worse death-censored 8-year graft survival (53% or 67%) than C4d- patients (66% or 81%; P<0.001). In Cox regression analysis, C4d was associated with a risk of graft loss independently of baseline confounders and ABMR morphology (hazard ratio, 1.85 [95% confidence interval, 1.34 to 2.57]; P<0.001). The risk was higher than that observed for C4d- patients, a finding that reached statistical significance in patients showing fewer than two different ABMR lesions. Moreover, in a mixed model, C4d was independently associated with a steeper decline of eGFR (slope per year, -8.23±3.97 ml/min per 1.73 m(2); P<0.001).
Conclusions:
These results suggest that detection of intragraft complement activation has strong independent value as an additional indicator of ABMR associated with adverse kidney transplant outcomes.
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