Evaluation of C1q Status and Titer of De Novo Donor-Specific Antibodies as Predictors of Allograft Survival.

De novo donor-specific antibodies (dnDSAs) that develop after renal transplantation are independent predictors of allograft loss. However, it is unknown if dnDSA C1q status or titer at the time of first detection can independently predict allograft loss. In a consecutive cohort of 508 renal transplant recipients, 70 developed dnDSAs. Histologic and clinical outcomes were correlated with the C1q assay or dnDSA titer. C1q positivity correlated with dnDSA titer (p < 0.01) and mean fluorescence intensity (p < 0.01) and was more common in class II versus class I dnDSAs (p < 0.01). C1q status correlated with tubulitis (p = 0.02) and C4d status (p = 0.03) in biopsies at the time of dnDSA development, but not T cell-mediated rejection (TCMR) or antibody-mediated rejection (ABMR). De novo DSA titer correlated with Banff g, i, t, ptc, C4d scores, TCMR (p < 0.01) and ABMR (p < 0.01). Post-dnDSA graft loss was observed more frequently in recipients with C1q-positve dnDSA (p < 0.01) or dnDSA titer ≥ 1:1024 (p ≤ 0.01). However, after adjustment for clinical phenotype and nonadherence in multivariate models, neither C1q status nor dnDSA titer were independently associated with allograft loss, questioning the utility of these assays at the time of dnDSA development.

Rates and determinants of progression to graft failure in kidney allograft recipients with de novo donor-specific antibody.

Understanding rates and determinants of clinical pathologic progression for recipients with de novo donor-specific antibody (dnDSA), especially subclinical dnDSA, may identify surrogate endpoints and inform clinical trial design. A consecutive cohort of 508 renal transplant recipients (n = 64 with dnDSA) was studied. Recipients (n = 388) without dnDSA or dysfunction had an eGFR decline of -0.65 mL/min/1.73 m(2) /year. In recipients with dnDSA, the rate eGFR decline was significantly increased prior to dnDSA onset (-2.89 vs. -0.65 mL/min/1.73 m(2) /year, p < 0.0001) and accelerated post-dnDSA (-3.63 vs. -2.89 mL/min/1.73 m(2) /year, p < 0.0001), suggesting that dnDSA is both a marker and contributor to ongoing alloimmunity. Time to 50% post-dnDSA graft loss was longer in recipients with subclinical versus a clinical dnDSA phenotype (8.3 vs. 3.3 years, p < 0.0001). Analysis of 1091 allograft biopsies found that dnDSA and time independently predicted chronic glomerulopathy (cg), but not interstitial fibrosis and tubular atrophy (IFTA). Early T cell-mediated rejection, nonadherence, and time were multivariate predictors of IFTA. Independent risk factors for post-dnDSA graft survival available prior to, or at the time of, dnDSA detection were delayed graft function, nonadherence, dnDSA mean fluorescence intensity sum score, tubulitis, and cg. Ultimately, dnDSA is part of a continuum of mixed alloimmune-mediated injury, which requires solutions targeting T and B cells.

Class II HLA epitope matching-A strategy to minimize de novo donor-specific antibody development and improve outcomes.

De novo donor-specific antibody (dnDSA) develops in 15-25% of renal transplant recipients within 5 years of transplantation and is associated with 40% lower graft survival at 10 years. HLA epitope matching is a novel strategy that may minimize dnDSA development. HLAMatchmaker software was used to characterize epitope mismatches at 395 potential HLA-DR/DQ/DP conformational epitopes for 286 donor-recipient pairs. Epitope specificities were assigned using single antigen HLA bead analysis and correlated with known monoclonal alloantibody epitope targets. Locus-specific epitope mismatches were more numerous in patients who developed HLA-DR dnDSA alone (21.4 vs. 13.2, p < 0.02) or HLA-DQ dnDSA alone (27.5 vs. 17.3, p < 0.001). An optimal threshold for epitope mismatches (10 for HLA-DR, 17 for HLA-DQ) was defined that was associated with minimal development of Class II dnDSA. Applying these thresholds, zero and 2.7% of patients developed dnDSA against HLA-DR and HLA-DQ, respectively, after a median of 6.9 years. Epitope specificity analysis revealed that 3 HLA-DR and 3 HLA-DQ epitopes were independent multivariate predictors of Class II dnDSA. HLA-DR and DQ epitope matching outperforms traditional low-resolution antigen-based matching and has the potential to minimize the risk of de novo Class II DSA development, thereby improving long-term graft outcome.

Evolution and clinical pathologic correlations of de novo donor-specific HLA antibody post kidney transplant.

The natural history for patients with de novo donor-specific antibodies (dnDSA) and the risk factors for its development have not been well defined. Furthermore, clinical and histologic correlation with serologic data is limited. We studied 315 consecutive renal transplants without pretransplant DSA, with a mean follow-up of 6.2 ± 2.9 years. Protocol (n = 215) and for cause (n = 163) biopsies were analyzed. Solid phase assays were used to screen for dnDSA posttransplant. A total of 47 out of 315 (15%) patients developed dnDSA at a mean of 4.6 ± 3.0 years posttransplant. Independent predictors of dnDSA were HLA-DRß1 MM > 0 (OR 5.66, p < 0.006); and nonadherence (OR 8.75, p < 0.001); with a strong trend toward clinical rejection episodes preceding dnDSA (OR 1.57 per rejection episode, p = 0.061). The median 10-year graft survival for those with dnDSA was lower than the No dnDSA group (57% vs. 96%, p < 0.0001). Pathology consistent with antibody-mediated injury can occur and progress in patients with dnDSA in the absence of graft dysfunction and furthermore, nonadherence and cellular rejection contribute to dnDSA development and progression to graft loss.

Banff '05 Meeting Report: differential diagnosis of chronic allograft injury and elimination of chronic allograft nephropathy ('CAN').

The 8th Banff Conference on Allograft Pathology was held in Edmonton, Canada, 15-21 July 2005. Major outcomes included the elimination of the non-specific term "chronic allograft nephropathy" (CAN) from the Banff classification for kidney allograft pathology, and the recognition of the entity of chronic antibody-mediated rejection. Participation of B cells in allograft rejection and genomics markers of rejection were also major subjects addressed by the conference.

The not-so-minimal lesions of the idiopathic nephrotic syndrome of childhood.

Dijkman et al. describe a unique form of glomerular involution in children with idiopathic nephrotic syndrome (INS). These lesions are small and sclerotic but retain their podocyte and parietal epithelial cell constituents. Multicenter studies are needed to address the clinical implications of the changing histological pattern of INS in children.

Aortic dissection in young patients with chronic hypertension.

We describe four patients aged 14 to 21 years who developed acute aortic dissection. In three of the four patients, the course was fatal, despite aggressive medical and surgical intervention. All four patients had sustained systemic hypertension related to chronic renal insufficiency. The patients had no other identifiable risk factors for aortic dissection, including congenital cardiovascular disease, advanced atherosclerosis, vasculitis, trauma, pregnancy, or family history of aortic dissection. Although aortic dissection is rare in individuals younger than 40 years of age, young patients with sustained systemic hypertension are at increased risk for this serious and often fatal condition. Physicians must be aware of this rare complication of hypertension and consider aortic dissection in the differential diagnosis of unusual chest, abdominal, and back pain in hypertensive children, adolescents, and young adults.

Does cytomegalovirus cause glomerular injury in renal allograft recipients?

The case of a 16-yr-old woman who received an ABO-incompatible renal allograft for end-stage renal disease due to membranoproliferative glomerulonephritis type I is presented. The patient's posttransplant course was complicated by cytomegalovirus (CMV) infection and the rare finding of glomerular CMV inclusions on renal biopsy. This article focuses on the pathology and pathogenesis of glomerular injury associated with CMV infection in renal allograft recipients and also reviews the epidemiology, clinical implications, diagnosis and management of CMV infection in these patients.

Risk factors for chronic rejection in pediatric renal transplant recipients--a single-center experience.

Chronic rejection (CR) is the most common cause of graft loss beyond the 1st posttransplant year. The aim of this analysis was to identify the risk factors for the development of CR in pediatric renal transplant recipients. Between June 1984 and March 1994, 217 renal transplants were performed in children at our center. Immunosuppression included prednisone, azathioprine, cyclosporine (CsA), and prophylactic antibody. Using multivariate analysis, we studied the impact of the following variables on the development of biopsy-proven CR: age at transplant (< or = 5 years, > 5 years), gender, race, transplant number (primary, retransplant), donor source (cadaver, living donor), donor age (< 20 years, 20-49 years, > 49 years), number of ABDR mismatches (0, 1-2, 3-4, 5-6), number of DR mismatches (0, 1, 2), percentage peak panel reactive antibody (PRA) (< or = 50%, > 50%), percentage PRA at transplantation (< or = 50%, > 50%), dialysis pretransplant, preservation time > 24 h, acute tubular necrosis requiring dialysis, initial CsA dosage (< or = 5 mg/kg per day, > 5 mg/kg per day), CsA dosage at 1 year posttransplant (< or = 5 mg/kg per day, > 5 mg/kg per day), acute rejection (AR), number of AR episodes (ARE) (1, > 1), timing of AR (< or = 6 months, > 6 months), reversibility of AR (complete, partial), and infection [cytomegalovirus (CMV), non-CMV viral, bacterial]. Risk factors for the development of CR in pediatric renal transplant recipients were: AR (P < 0.0001, odds ratio 19.4), multiple ARE (> 1 vs. 1) (P < 0.0001, odds ratio 30.1), and high percentage peak PRA (> 50%) (P < 0.03, odds ratio 3.6).

Cardiac tamponade as a terminal event in the hemolytic uremic syndrome in childhood.

The case of a 6-year-old Inuit female with the epidemic form of hemolytic uremic syndrome (HUS) with myocardial involvement and probable cardiac tamponade is presented. This case illustrates the multisystemic nature of the syndrome, and to our knowledge, cardiac tamponade as a probable terminal event in HUS has not been reported previously.

Rapid nonradioactive in situ hybridization for interleukin-2 mRNA with riboprobes generated using the polymerase chain reaction.

In situ hybridization is a technique with widespread application. However, its usefulness has been limited by the need for radioactive materials and the requirement for the DNA to be cloned onto an appropriate vector. We have utilized the polymerase chain reaction to directly incorporate a T7 RNA polymerase promoter sequence onto the cDNA for interleukin-2. Digoxigenin-labelled riboprobes were then synthesized using this PCR product as a template. The digoxigenin-labelled riboprobes were then used in non-radioactive in situ hybridization to detect messenger RNA for interleukin-2 in mitogen stimulated peripheral blood mononuclear cells. This methodology has the potential for widespread application in immunology and cytokine research.