A multicenter report on the utilization of Banff grading in acute renal rejection. The 1995 Efficacy Endpoints Conference

BK virus nephropathy after simultaneous pancreas-kidney transplantation

BACKGROUND

BK virus nephropathy (BKVN) was reported in up to 7.5% of patients after simultaneous pancreas-kidney transplantation (SPK). Its management by reduction in immunosuppression might pre-dispose to pancreatic graft loss.

METHODS

A retrospective analysis of 178 SPK recipients was performed. All patients received thymoglobulin, daclizumab and a maintenance of low-dose steroids, tacrolimus, and either sirolimus or mycophenolate.

RESULTS

Two (1.1%) patients were identified with BKVN. Time of diagnosis was 22 and 45 months after transplant. Both patients had superimposed calcineurin toxicity in their graft biopsies. Immunosuppression was reduced in both patients, and leflunomide (LEF) was used in one patient. Concurrent kidney rejection episodes were treated with steroid pulses in both patients. One kidney graft improved with a last estimated glomerular filtration rate (GFR) of 43 mL/min, and another kidney graft showed limited improvement with a last GFR of 30 mL/min. Pancreatic graft function remained excellent in both patients as assessed by serum c-peptide, glycosylated hemoglobin, amylase-lipase, and urine amylase levels.

CONCLUSION

Low incidence of BKVN was observed in our SPK series. Reduction in immunosuppression and sometimes LEF can be effective. The underlying mechanism of stable pancreatic allograft function despite ongoing kidney rejection warrants further investigation.

Scoring total inflammation is superior to the current Banff inflammation score in predicting outcome and the degree of molecular disturbance in renal allografts

Emerging molecular analysis can be used as an objective and independent assessment of histopathological scoring systems. We compared the existing Banff i-score to the total inflammation (total i-) score for assessing the molecular phenotype in 129 renal allograft biopsies for cause. The total i-score showed stronger correlations with microarray-based gene sets representing major biological processes during allograft rejection. Receiver operating characteristic curves showed that total-i was superior (areas under the curves 0.85 vs. 0.73 for Banff i-score, p = 0.012) at assessing an abnormal cytotoxic T-cell burden, because it identified molecular disturbances in biopsies with advanced scarring. The total-i score was also a better predictor of graft survival than the Banff i-score and essentially all current diagnostic Banff categories. The exception was antibody-mediated rejection which is able to predict graft loss with greater specificity (96%) but at low sensitivity (38%) due to the fact that it only applies to cases with this diagnosis. The total i-score is able to achieve moderate sensitivities (60-80%) with losses in specificity (60-80%) across the whole population. Thus, the total i-score is superior to the current Banff i-score and most diagnostic Banff categories in predicting outcome and assessing the molecular phenotype of renal allografts.

Heterogeneity in the evolution and mechanisms of the lesions of kidney allograft rejection in mice

The natural history and pathogenesis of the pathologic lesions that define rejection of kidney transplants have not been well characterized. We studied the evolution of the pathology of rejection in mouse kidney allografts, using four strain combinations across full major histocompatibility complex (MHC) plus nonMHC disparities, to permit more general conclusions. Interstitial infiltrate, MHC induction, and venulitis appeared by day 5, peaked at day 7-10, then stabilized or regressed by day 21. In contrast, tubulitis, arteritis, and glomerulitis were absent or mild at days 5 and 7, but progressed through day 21, indicating separate regulation and homeostatic control of these lesions. Edema, hemorrhage, and necrosis also increased through day 21. All lesions were T-dependent, failing to develop in T-cell-deficient hosts. Allografts into immunoglobulin-deficient hosts manifested typical infiltration, MHC induction, and tubulitis at days 7 and 21, indicating that these lesions are alloantibody-independent. However at day 21 kidneys rejecting in immunoglobulin-deficient hosts showed decreased edema, arteritis, venulitis, and necrosis. Thus the three groups of lesions are: T-cell-mediated interstitial infiltration, MHC induction, and venulitis, which develops rapidly then stabilizes; slower but progressive T-cell-mediated tubulitis and arteritis; and late antibody-mediated endothelial injury, which contributes to late edema, arteritis, and venulitis.

The US multicenter double-blind, randomized, phase III trial of thymoglobulin versus atgam in the treatment of acute graft rejection episodes following renal transplantation: rationale for study design

In this study intended to establish equivalence between two antibody therapies for acute rejection in kidney transplant recipients, it was important to develop a rigorous protocol. Assurance of the presence of acute rejection was imperative. Therefore, due to the lack of literature support for clinical assessment of renal dysfunction, histologic diagnosis of acute rejection was required for enrollment in the study. Likewise, supportive literature for a correlation between response to anti-rejection therapy and the severity of rejection lead to the decision that the study should be stratified by a measurement of rejection severity for which Banff criteria were used. Finally, quantification of the response to therapy was also measured against the available literature and a large, newly developed international database of kidney transplant rejection episodes (the Efficacy Endpoints database) where serum creatinine, expressed as a percentage of the baseline level at the time of rejection was shown to be the most effective, available clinical marker of rejection response. Therefore, the US Multicenter Phase III Trial for comparing Thymoglobulin to Atgam in the treatment of acute rejection exhibits a unique and detailed study design that could be implemented in future trials as well as in clinical practice to improve assessment of outcomes.