title: Focal C4d+ in renal allografts is associated with the presence of donor-specific antibodies and decreased allograft survival.
abstract: Diffuse peritubular capillary C4d deposition in renal allograft biopsies is associated with donor-specific antibodies (DSA) and graft failure. The significance of focal C4d+ is unclear. We reviewed 368 biopsies from 301 patients performed for renal dysfunction or proteinuria over 5 years. Diffuse C4d+, focal C4d+ and C4d- detected by immunofluorescence occurred in 9.5%, 20.9% and 69.4% of biopsies, respectively. Patients were similar in gender, age, cause of renal disease, donor source, HLA mismatch, serum creatinine at baseline and interval from transplantation to biopsy. Diffuse and focal C4d+ were associated with acute cellular rejection (p < 0.001). Transplant glomerulopathy was associated with diffuse C4d+. DSA at the time of biopsy, were positive in 79.3% of diffusely C4d+ patients, 68.8% of those with focal C4d+ (p = 0.27) and 9.9% of patients with C4d- (p < 0.001, compared to either the focal or diffuse groups, respectively). Allograft survival at 40 months was lower in diffuse C4d+ compared to the C4d- group (p = 0.014), but not when compared to the focal C4d+ group. There was a clear trend toward worse graft survival in patients with focal C4d+ in this time interval, but focal C4d+ compared to both diffuse C4d+ and C4d-groups was not statistically significant (p = 0.08).
authors.affiliation: Department of Internal Medicine, Renal Division, Washington University, St. Louis, MO, USA.
authors.forename: R L
authors.initials: RL
authors.lastname: Kedainis
authors.forename: M J
authors.initials: MJ
authors.lastname: Koch
authors.forename: D C
authors.initials: DC
authors.lastname: Brennan
authors.forename: H
authors.initials: H
authors.lastname: Liapis