Urinary C4d does not correlate with C4d-staining in peritubular capillaries but reflects nonspecific glomerular injury.

Hönger G; Mayr M; Dickenmann M; Mihatsch MJ; Schaub S

doi:10.1097/TP.0b013e3181641d8c

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Journal article

Urinary C4d does not correlate with C4d-staining in peritubular capillaries but reflects nonspecific glomerular injury.

Hönger G Clinic for Transplantation Immunology and Nephrology, University Hospital Basel, Basel, Switzerland.
Mayr M
Dickenmann M
Mihatsch MJ
Schaub S

2008-03-19

Published in:

Transplantation. - 2008

English BACKGROUND
C4d-staining in peritubular capillaries (PTC) in allograft biopsies is a hallmark of antibody-mediated rejection (AMR). This study investigated whether urinary C4d correlates with C4d-staining in PTC, allowing for a noninvasive screening procedure.

METHODS
Urine samples from 34 patients with diffuse C4d-staining in PTC (C4d-pos group) and 68 urine samples from patients with negative C4d-staining in PTC (C4d-negative group) matched 1:2 according to proteinuria and time posttransplant were compared regarding urinary C4d-levels.

RESULTS
Overall, urinary C4d/creatinine-ratios (C4d/C) were not different between the C4d-positive and the C4d-negative group (P=0.55). Urinary C4d/C strongly correlated with total protein/creatinine-ratios (P/C) (r2=0.53; P<0.0001) and albumin/creatinine-ratios (r2=0.52; P<0.0001). C4d/C were not different between C4d-pos and C4d-negative patients with P/C>50 mg/mmol (P=0.57) and P/C<50 mg/mmol (P=0.65), respectively. However, in both the C4d-positive and the C4d-negative group urinary C4d/C were significantly higher in patients with P/C>50 mg/mmol than in patients with P/C<50 mg/mmol (P

CONCLUSION
Urinary C4d does not correlate with C4d-staining in PTC but reflects nonspecific glomerular injury. Therefore, urinary C4d is likely not a useful biomarker for non-invasive screening and monitoring of AMR.

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