title: Association of glomerular C4d deposition with various demographic data in IgA nephropathy patients; a preliminary study.
abstract: BACKGROUND
  IgA nephropathy (IgAN) is the most prevalent primary chronic glomerulopathy worldwide. Thus, it is of vital importance to search for factors aggravating the disease progress, monitor disease activity and predict disease-specific therapy. C4d is a well-known biomarker of the complement cascade with a potential to meet the above needs.
  
  
  OBJECTIVE
  The aim of our study was, therefore, to determine whether C4d staining at the time of kidney biopsy had any correlation with the demographic, clinical and biochemical variables in IgAN.
  
  
  METHODS
  The definition of IgAN requires the presence of diffuse and global IgA deposits which were graded ≥2+ and weak C1q deposition. C4d immunohistochemical staining was conducted retrospectively on 29 renal biopsies of patients with IgAN, which were selected randomly from all biopsies. C4d immunohistochemical staining was performed on 3-μm deparaffinized and rehydrated sections of formaldehyde-fixed, paraffin-embedded renal tissues.
  
  
  RESULTS
  Of 29 selected patients, 68% were male. In this study, 54.2±25 percent of glomeruli in all biopsies were positive for C4d. The mean and standard deviation (SD) of serum creatinine and the magnitude of proteinuria were 1.72±1.2 mg/dl and 1582±1214 mg/day, respectively. In this study, we observed statistically significant correlations of percent C4d positivity with the serum creatinine (r=0.61, p=0.0005), magnitude of proteinuria (r=0.72, p=0.0001), the proportion of globally sclerotic glomeruli (r=0.43, p=0.02) and the proportion of tubulointerstitial fibrosis (r=0.54, p=0.0023).
  
  
  CONCLUSIONS
  The results from our investigation on C4d positivity in biopsy-proven cases of IgAN are in accord with some of the previous studies. These findings, however, require further validation in larger samples.
authors: Department of Nephrology, Division of Nephropathology, Isfahan University of Medical Sciences, Isfahan, Iran.
authors: Hamid
authors: H
authors: Nasri
authors: Department of Epidemiology, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors: Ali
authors: A
authors: Ahmadi
authors: Medical Plants Research Center, Shahrekord University of Medical Sciences, Sharhekord, Iran.
authors: Mahmood
authors: M
authors: Rafieian-Kopaei
authors: Department of Internal Medicine, Imam Khomeini Hospital, Ardabil University of Medical Sciences, Ardabil, Iran.
authors: Bahman
authors: B
authors: Bashardoust
authors: School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
authors: Parto
authors: P
authors: Nasri
authors: Department of Histopathology, Sindh Institute of Urology and Transplantation (SIUT), Karachi, Pakistan.
authors: Muhammed
authors: M
authors: Mubarak
keywords: C4d; Complement; Glomerulopathy; IgA nephropathy; Immunohistochemistry