Acute renal allograft rejection: diagnostic significance of focal peritubular capillary C4d.
BACKGROUND
Focal PTC C4d staining in acute renal allograft rejection has not been studied extensively.


METHODS
Renal allograft biopsies performed after October 2003, representing the first episode of acute rejection (AR) in recipients with > or = 12 months follow-up postbiopsy, were assessed for extent of C4d and correlated with morphology, ELISA screen, donor-specific antibodies (DSA), response to treatment, and outcome.


RESULTS
In 106 biopsies (16 C4d-diffuse; 24 C4d-focal; 66 C4d-negative), there were no differences among the three groups in terms of timing or grade of AR, creatinine level, tacrolimus level, and grade of interstitial fibrosis/tubular atrophy or graft loss. The C4d-diffuse group was significantly associated with less tubulitis (P=0.0021), and more chronic allograft arteriopathy (P=0.0527). Incomplete response to steroid therapy was more frequent in C4d-diffuse/focal compared with negative cases (P=0.0492). DSA frequency within 1 year of AR was highest in the C4d-diffuse (94%), followed by C4d-focal (38%), and C4d-negative (17%) groups (P<0.0001).


CONCLUSIONS
Focal PTC C4d was associated with circulating antibodies, with a 2-fold greater diagnostic sensitivity than negative C4d staining. The finding of diffuse C4d on follow-up biopsy was significantly associated with graft loss at 1 year, regardless of index biopsy C4d results.
Kayler
Liise K
LK
Department of Surgery, University of Florida Medical Center, Gainesville, FL 32610-0286, USA. liisekayler@yahoo.com
Kiss
Lawrence
L
Sharma
Vivek
V
Mohanka
Ravi
R
Zeevi
Adriana
A
Girnita
Alin
A
Shapiro
Ron
R
Randhawa
Parmjeet S
PS
D002196:Capillaries / Q000473:pathology; D015935:Complement C4b / Q000032:analysis*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006084:Graft Rejection / Q000175:diagnosis* / Q000276:immunology / Q000473:pathology; D006085:Graft Survival / Q000276:immunology; D006650:Histocompatibility Testing; D006801:Humans; D016030:Kidney Transplantation / Q000473:pathology*; D007684:Kidney Tubules / Q000098:blood supply*; D008297:Male; D008875:Middle Aged; D016035:Pancreas Transplantation / Q000473:pathology; D010446:Peptide Fragments / Q000032:analysis*
D010446:Peptide Fragments; D015935:Complement C4b; C032261:complement C4d