Glomerular C4d Staining Research Articles

Significance of Peritubular Capillary, Glomerular, and Arteriolar C4d Staining Patterns in Paraffin Sections of Early Kidney Transplant Biopsies

Although diffuse linear C4d deposition in peritubular capillaries (PTCs) is a well-established criterion of alloantibody-mediated kidney transplant rejection, the actual relevance of focal or granular C4d deposits or staining outside PTC (glomeruli and arterioles) has yet to be established. This study was designed to evaluate the diagnostic significance of such nontypical C4d staining patterns. A total of 539 early indication biopsies (329 kidney transplants) were analyzed by immunohistochemistry using a polyclonal anti-C4d antibody. We found a close interrelationship between diffuse or focal linear C4d deposition in PTC, linear endothelial deposition in glomeruli, and arteriolar C4d. These specific patterns were also related to transplant glomerulitis and recipient presensitization. No such associations, however, were observed for other patterns, such as granular C4d in PTC. Detection of diffuse but not focal linear C4d in PTC was found to be associated with adverse allograft survival (5-year death-censored graft survival: 48% vs. 82%, 89%, or 84% in patients with focal, minimal, or no C4d, respectively; P<0.0001). Univariate analysis also revealed inferior graft survival in recipients with linear C4d in glomeruli (P=0.02). Applying multivariate Cox regression analysis, however, only diffuse linear PTC staining was found to be predictive of graft loss (hazard ratio 3.95 [95% confidence interval 1.62-9.60]; P=0.002). There might be a relationship between humoral alloimmunity and distinct less established staining patterns, such as focal linear C4d in PTC, endothelial C4d in glomeruli, or arteriolar C4d. Nevertheless, our results reemphasize the prognostic value of diffuse linear PTC staining.

Association between anti-β2 glycoprotein I antibodies and renal glomerular C4d deposition in lupus nephritis patients with glomerular microthrombosis: a prospective study of 155 cases

Glomerular microthrombosis (GMT) is a common vascular change in patients with lupus nephritis (LN). The mechanism underlying GMT is still unknown. In our previous study, we found that the level of IgG anti-beta2 glycoprotein I (beta2GPI) antibodies was higher in the LN-GMT group than in the LN-non-GMT group, which indicated that anti-beta2GPI antibodies may play a role in GMT formation. Many studies have demonstrated that the activation of the classical complement pathway may play a critical role in fetal loss and aPL-induced thrombosis formation. To investigate whether complement activation plays a role in GMT formation and to evaluate its relationship with aPL, we prospectively investigated deposition of C4d in 155 renal biopsy specimens of LN patients. The results revealed a strong relationship between the intensity of glomerular C4d staining and the presence of microthrombi (p < 0.001). The detection rate of IgG anti-beta2GPI antibodies was higher in the LN-GMT group than in the LN-non-GMT group (p < 0.05). Further, the intensity of glomerular C4d staining was significantly related with IgG anti-beta2GPI antibodies (p < 0.05). The results of our study suggest that anti-beta2GPI antibodies may play a role in GMT formation, and this process might involve complement activation.

Potential for glomerular C4d as an indicator of thrombotic microangiopathy in lupus nephritis

In patients with systemic lupus erythematosus (SLE) and lupus nephritis, the presence of antiphospholipid antibodies (aPL) is considered to be an indication of increased risk of thrombotic microangiopathy, a serious complication of SLE. Previous studies have demonstrated a critical role for activation of the classical pathway of complement that leads to thrombotic injury in the presence of aPL. This study was undertaken to investigate whether C4d deposition in lupus nephritis is related to circulating aPL and the presence of renal microthrombi. Deposition patterns of C4d in 44 renal biopsy samples obtained from 38 patients with biopsy-proven lupus nephritis were determined by staining with a polyclonal anti-C4d antibody. A phosphotungstic acid-hematoxylin stain was used to identify fibrin microthrombi. Clinical data (serum creatinine levels and presence or absence of aPL) were obtained and correlated with findings in the renal biopsy specimens. Patients were categorized as having aPL (n = 20) or not having aPL (n = 18). A strong relationship between the intensity of glomerular C4d staining and the presence of microthrombi was found (P < 0.002). Intense glomerular C4d deposition was present in 7 of 8 biopsy samples showing renal microthrombi. Neither C4d deposition nor the presence of microthrombi was correlated with aPL status. Our findings suggest that activation of the classical pathway of complement plays a pathogenic role in the development of renal tissue injury leading to thrombosis, irrespective of the type of circulating antibodies present. Immunodetection of glomerular C4d deposition in renal biopsy samples could be a convenient method of identifying patients at risk of thrombotic microangiopathy.

Histologic Findings of Antibody-Mediated Rejection in ABO Blood-Group-Incompatible Living-Donor Kidney Transplantation

The purpose of this study was to characterize the histology of antibody-mediated rejection (AMR) in ABO blood-group-incompatible (ABOI) kidney transplants as well as on protocol biopsies performed at the time of stable allograft function. Between 5/99 and 1/02, we performed 32 ABOI kidney transplants (13 A2, 19 non-A2 blood-group living donors). Nineteen biopsies were performed for allograft dysfunction, and 127 protocol biopsies were performed 0, 3, 7, 14, 28 days and 3 and 12 months post transplant. Twenty-five of 32 patients have functioning allografts (mean 585 days post transplant). Nine of 32 (28%) developed clinical AMR. Biopsy revealed glomerular thrombi (78%), mesangiolysis (78%), peritubular capillary C4d staining (56%) and neutrophil infiltration (67%), interstitial hemorrhage and necrosis (56%) and arteriolar thrombi (33%). Subclinical AMR was diagnosed by protocol biopsies in four patients. Findings consisted of glomerular thrombi (100%), mesangiolysis (25%), and C4d staining (100%). In late protocol biopsies performed 214–420 days post transplant, mild mesangiolysis was seen in 2/17 (11.7%), and C4d immunostaining was detected in 3/12 (25%). AMR is characterized by glomerular thrombi, mesangiolysis, peritubular capillary neutrophil infiltration interstitial hemorrhage, necrosis, and C4d deposition. Glomerular thrombi appear early in AMR and may appear prior to graft dysfunction.