title: Glomerular c4d staining can be an indicator of disease activity in lupus nephritis.
abstract: BACKGROUND
  Abnormalities in complement activation and clearance of immune complexes by erythrocytes are the central pathogenic mechanisms in systemic lupus erythematosus (SLE). Serum C4d level, which is a degradation product of complement factor C4, was found to be a sensitive indicator of SLE activity. Our aim was to determine whether glomerular C4d staining could be a useful marker of disease activity in patients with lupus nephritis.
  
  
  METHODS
  This retrospective study included all consecutive patients who underwent a renal biopsy at our center between January 2005 and December 2009. A total of 29 patients with IgA nephritis were enrolled, and renal biopsy specimens of 24 patients have been evaluated. We evaluated baseline age, sex, hypertension, serum creatinine level, glomerular filtration rate (GFR), urine protein, and glomerular C4d staining. The primary endpoint of this study was the onset of end-stage renal disease (ESRD) in the course of study.
  
  
  RESULTS
  Fourteen (58%) patients were C4d+ and 10 (42%) patients C4d-. Urinary protein excretion was more elevated in C4d+ group (p = 0.0001). The renal biopsy showed that activity index score >12 was a higher proportion in C4d+ patients. The patients were followed up for 3.5 years. Four patients in the C4d+ group evolved to ESRD in the follow-up, but none of the patients in the C4d- group (p = 0.064).
  
  
  CONCLUSIONS
  We found a relationship between glomerular C4d staining and activity of lupus nephritis. C4d staining may be a useful marker to predict the prognosis of lupus nephritis.
authors.affiliation: Department of Nephrology, Izmir Ataturk Training and Research Hospital, Karabağlar Izmir, Turkey. drosahin@yahoo.com
authors.forename: Osman Zikrullah
authors.initials: OZ
authors.lastname: Sahin
authors.forename: Sukran
authors.initials: S
authors.lastname: Gurses
authors.forename: Funda
authors.initials: F
authors.lastname: Taslı
authors.forename: Hakan
authors.initials: H
authors.lastname: Yavas
authors.forename: Rıfkı
authors.initials: R
authors.lastname: Ersoy
authors.forename: Atilla
authors.initials: A
authors.lastname: Uzum
authors.forename: Mustafa
authors.initials: M
authors.lastname: Cirit
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000032:analysis*; D001707:Biopsy, Needle; D015331:Cohort Studies; D003181:Complement C4 / Q000378:metabolism*; D015935:Complement C4b / Q000032:analysis*; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007150:Immunohistochemistry; D007676:Kidney Failure, Chronic / Q000453:epidemiology / Q000503:physiopathology; D007678:Kidney Glomerulus / Q000737:chemistry* / Q000473:pathology*; D008181:Lupus Nephritis / Q000150:complications / Q000473:pathology* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010446:Peptide Fragments / Q000032:analysis*; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D013194:Staining and Labeling; D018709:Statistics, Nonparametric; D055815:Young Adult
chemical_list: D015415:Biomarkers; D003181:Complement C4; D010446:Peptide Fragments; D015935:Complement C4b; C032261:complement C4d