The Banff 2015 Kidney Meeting Report: Current Challenges in Rejection Classification and Prospects for Adopting Molecular Pathology.

The XIII Banff meeting, held in conjunction the Canadian Society of Transplantation in Vancouver, Canada, reviewed the clinical impact of updates of C4d-negative antibody-mediated rejection (ABMR) from the 2013 meeting, reports from active Banff Working Groups, the relationships of donor-specific antibody tests (anti-HLA and non-HLA) with transplant histopathology, and questions of molecular transplant diagnostics. The use of transcriptome gene sets, their resultant diagnostic classifiers, or common key genes to supplement the diagnosis and classification of rejection requires further consensus agreement and validation in biopsies. Newly introduced concepts include the i-IFTA score, comprising inflammation within areas of fibrosis and atrophy and acceptance of transplant arteriolopathy within the descriptions of chronic active T cell-mediated rejection (TCMR) or chronic ABMR. The pattern of mixed TCMR and ABMR was increasingly recognized. This report also includes improved definitions of TCMR and ABMR in pancreas transplants with specification of vascular lesions and prospects for defining a vascularized composite allograft rejection classification. The goal of the Banff process is ongoing integration of advances in histologic, serologic, and molecular diagnostic techniques to produce a consensus-based reporting system that offers precise composite scores, accurate routine diagnostics, and applicability to next-generation clinical trials.

Splenic Irradiation for the Treatment of Severe Antibody-Mediated Rejection.

Patients requiring desensitization prior to renal transplantation are at risk for developing severe antibody-mediated rejection (AMR) refractory to treatment with plasmapheresis and intravenous immunoglobulin (PP/IVIg). We have previously reported success at graft salvage, long-term graft survival and protection against transplant glomerulopathy with the use of eculizumab and splenectomy in addition to PP/IVIg. Splenectomy may be an important component of this combination therapy and is itself associated with a marked reduction in donor-specific antibody (DSA) production. However, splenectomy represents a major operation, and some patients with severe AMR have comorbid conditions that substantially increase their risk of complications during and after surgery. In an effort to spare recipients the morbidity of a second operation, we used splenic irradiation in lieu of splenectomy in two incompatible live donor kidney transplant recipients with severe AMR in addition to PP/IVIg, rituximab and eculizumab. This novel approach to the treatment of severe AMR was associated with allograft salvage, excellent graft function and no short- or medium-term adverse effects of the radiation therapy. One-year surveillance biopsies did not show transplant glomerulopathy (tg) on light microscopy, but microcirculation inflammation and tg were present on electron microscopy.

Presentation and Outcomes of C4d-Negative Antibody-Mediated Rejection After Kidney Transplantation.

The updated Banff classification allows for the diagnosis of antibody-mediated rejection (AMR) in the absence of peritubular capillary C4d staining. Our objective was to quantify allograft loss risk in patients with consistently C4d-negative AMR (n = 51) compared with C4d-positive AMR patients (n = 156) and matched control subjects without AMR. All first-year posttransplant biopsy results from January 2004 through June 2014 were reviewed and correlated with the presence of donor-specific antibody (DSA). C4d-negative AMR patients were not different from C4d-positive AMR patients on any baseline characteristics, including immunologic risk factors (panel reactive antibody, prior transplant, HLA mismatch, donor type, DSA class, and anti-HLA/ABO-incompatibility). C4d-positive AMR patients were significantly more likely to have a clinical presentation (85.3% vs. 54.9%, p < 0.001), and those patients presented substantially earlier posttransplantation (median 14 [interquartile range 8-32] days vs. 46 [interquartile range 20-191], p < 0.001) and were three times more common (7.8% vs 2.5%). One- and 2-year post-AMR-defining biopsy graft survival in C4d-negative AMR patients was 93.4% and 90.2% versus 86.8% and 82.6% in C4d-positive AMR patients, respectively (p = 0.4). C4d-negative AMR was associated with a 2.56-fold (95% confidence interval, 1.08-6.05, p = 0.033) increased risk of graft loss compared with AMR-free matched controls. No clinical characteristics were identified that reliably distinguished C4d-negative from C4d-positive AMR. However, both phenotypes are associated with increased graft loss and thus warrant consideration for intervention.

Quantifying renal allograft loss following early antibody-mediated rejection.

Unlike antibody-mediated rejection (AMR) with clinical features, it remains unclear whether subclinical AMR should be treated, as its effect on allograft loss is unknown. It is also uncertain if AMR's effect is homogeneous across donor (deceased/live) and (HLA/ABO) antibody types. We compared 219 patients with AMR (77 subclinical, 142 clinical) to controls matched on HLA/ABO-compatibility, donor type, prior transplant, panel reactive antibody (PRA), age and year. One and 5-year graft survival in subclinical AMR was 95.9% and 75.7%, compared to 96.8% and 88.4% in matched controls (p = 0.0097). Subclinical AMR was independently associated with a 2.15-fold increased risk of graft loss (95% CI: 1.19-3.91; p = 0.012) compared to matched controls, but not different from clinical AMR (p = 0.13). Fifty three point two percent of subclinical AMR patients were treated with plasmapheresis within 3 days of their AMR-defining biopsy. Treated subclinical AMR patients had no difference in graft loss compared to matched controls (HR 1.73; 95% CI: 0.73-4.05; p = 0.21), but untreated subclinical AMR patients did (HR 3.34; 95% CI: 1.37-8.11; p = 0.008). AMR's effect on graft loss was heterogeneous when stratified by compatible deceased donor (HR = 4.73; 95% CI: 1.57-14.26; p = 0.006), HLA-incompatible deceased donor (HR = 2.39; 95% CI: 1.10-5.19; p = 0.028), compatible live donor (no AMR patients experienced graft loss), ABO-incompatible live donor (HR = 6.13; 95% CI: 0.55-67.70; p = 0.14) and HLA-incompatible live donor (HR = 6.29; 95% CI: 3.81-10.39; p < 0.001) transplant. Subclinical AMR substantially increases graft loss, and treatment seems warranted.

Subclinical rejection in stable positive crossmatch kidney transplant patients: incidence and correlations.

We reviewed 116 surveillance biopsies obtained approximately 1, 3, 6 and 12 months posttransplantation from 50 +XM live donor kidney transplant recipients to determine the frequency of subclinical cell-mediated rejection (CMR) and antibody-mediated rejection (AMR). Subclinical CMR was present in 39.7% of the biopsies at 1 month and >20% at all other time points. The presence of diffuse C4d on biopsies obtained at each time interval ranged from 20 to 30%. In every case, where histological and immunohistological findings were diagnostic for AMR, donor-specific antibody was found in the blood, challenging the long-held belief that low-level antibody could evade detection due to absorption on the graft. Among clinical factors, only recipient age was associated with subclinical CMR. Clinical factors associated with subclinical AMR were recipient age, positive cytotoxic crossmatch prior to desensitization and two mismatches of HLA DR 51, 52 and 53 alleles. Surveillance biopsies during the first year post-transplantation for these high-risk patients uncover clinically occult processes and phenotypes, which without intervention diminish allograft survival and function.

Characteristics and sequelae of peritonitis in diabetics and nondiabetics receiving chronic intermittent peritoneal dialysis.

To evaluate the effect of diabetic status upon peritoneal dialysis-associated peritonitis, the characteristics and sequelae of 159 episodes of peritonitis were reviewed in 26 diabetic and 59 nondiabetic peritoneal dialysis patients. There was no difference between the two patient groups in peritonitis occurrence rates or in individual patient attack rate. The spectra of etiologic florae were comparable, although the nondiabetic group had a greater incidence of Staphylcoccus aureus and fungal peritonitis. Presenting symptomatology, ascitic fluid characteristics, duration of illness, and sequelae of peritonitis, including catheter loss and death, were similar in diabetics and nondiabetics. Dialysis peritonitis is manifested by a spectrum of illness ranging from brief asymptomatic infection to painful prolonged disease; however, the latter course is not more common in diabetics. Further, in diabetics, peritonitis is neither a more frequent event, nor inherently a greater risk, than in nondiabetics.

Donor horseshoe kidneys for transplantation.

BACKGROUND: Experience with donor horseshoe kidneys for transplantation is very limited. Currently, horseshoe kidneys may be underutilized for transplantation because of the greater incidence of vascular anomalies, associated renal anomalies, and predisposition to renal disease. METHODS: In this report, we review five transplantations using horseshoe kidneys: the largest reported institutional experience. In addition, a review of all published cases in the English literature is performed. RESULTS: All five patients underwent successful renal transplantations with a median follow-up of 35 months. One patient lost his kidney from recurrent disease soon after transplantation. CONCLUSION: With appropriate reconstruction of the vessels, careful division of the isthmus, and avoidance of ureteral obstruction, long-term data revealed good graft survival of donor horseshoe kidneys in renal transplantation.

Laparoscopic live donor nephrectomy: the recipient.

BACKGROUND: Laparoscopic live donor nephrectomy offers advantages to the donor in terms of decreased pain and shorter recuperation. Heretofore no detailed analysis of the recipient of laparoscopically procured kidneys has been performed. The purpose of this study was to determine whether laparoscopic donor nephrectomy had any deleterious effect on the recipient. METHODS: A retrospective review was conducted of all live donor renal transplantations performed from January 1995 through April 1998. The control group received kidneys procured via a standard flank approach (Open). Rejection was diagnosed histologically. Creatinine clearance was calculated using the Cockroft-Gault formula. RESULTS: A total of 110 patients received kidneys from laparoscopic (Lap) and 48 from open donors. One-year recipient (100% vs. 97.0%) and graft (93.5% vs. 91.1%) survival rates were similar for the Open and Lap groups, respectively. A similar incidence of vascular thrombosis (3.4% vs. 2.1%, P=NS) and ureteral complications (9.1% vs. 6.3%, P=NS) were seen in the Lap and Open groups, respectively. The incidence of acute rejection for the first month was 30.1% for the Lap group and 31.9% for the Open group (P=NS). The rate of decline of serum creatinine level in the early posttransplantation period was initially greater in the Open group, but by postoperative day 4 no significant difference existed. No difference was observed in allograft function long-term. The median length of hospital stay was 7.0 days for both groups. CONCLUSIONS: Laparoscopic live donor nephrectomy does not adversely effect recipient outcome. The previously demonstrated benefits to the donor, and the increased willingness of individuals to undergo live kidney donation, coupled with the acceptable outcomes experienced by recipients of laparoscopically procured kidneys justifies the continued development and adoption of this operation.

Impact of donor/recipient traits independent of rejection on long-term renal function.

This study describes renal function at multiple points in time after transplantation and the influence of donor and recipient factors independent of rejection on this function. Donor and recipient records for 83 consecutive cadaveric renal transplants performed between 1992 and 1994 at Johns Hopkins Bayview Medical Center were reviewed retrospectively. Donor age, gender, weight, terminal serum creatinine (Cr), intensive care unit days, blood pressure, presence of cardiac arrest, kidney only versus multiple organ donation, and cold ischemia time and recipient age, gender, weight, pretransplant pregnancy status, and rejection episodes were recorded. The influences of each of these parameters on changes in recipient Cr clearance over time (derived using the Cockcroft-Gault formula from recipient serum Cr at 3 months and annually up to 5 years) were analyzed first individually, then together in an analysis with multiple explanatory variables. Parameters indicative of donor ischemia (ie, donor blood pressure, pressor administration, and occurrence of cardiac arrest) were not predictive of the course of recipient Cr clearance. With the inclusion of rejection, this analysis shows the magnitude of the independent effects that donor age, donor Cr clearance, and recipient gender have on the subsequent time course of recipient Cr clearance (P < 0.05). Recipient gender and the presence of rejection appear to have a fixed effect on the level of Cr clearance, whereas donor age and donor Cr clearance appear to influence the level and the time course of recipient Cr clearance. Of all these factors, donor age appears to have the greatest impact on recipient Cr clearance at all times. Analyzing renal function in this way may prove to be a more sensitive indicator than actuarial survival analysis for evaluating the early effects of changes in transplantation protocols and pharmacologic interventions.

Transplantation of single and paired pediatric kidneys into adult recipients.

BACKGROUND: The transplantation of kidneys from cadaveric donors < or = 5 years of age into adult recipients is controversial. The large disparity between donor renal mass and recipient body mass is feared to be problematic. Controversy also exists whether to transplant kidneys from these young donors individually or as a pair into a single recipient. STUDY DESIGN: We retrospectively reviewed our experience from January 1991 to January 1995 with 22 adult renal transplantations using kidneys from cadaveric donors < or = 5 years of age. Ten patients received single allografts. Twelve received organs paired en bloc. Fifty-two adult recipients from cadaveric donors aged 18-55 years served as controls. All patients received cyclosporine-based immunosuppression. Recipient characteristics did not differ significantly between the groups. RESULTS: Actuarial patient and graft survival rates were similar for the two groups. The incidence of urinary complications was higher in the recipients of pediatric kidneys than in the adult-donor group (18.2% versus 3.8%, respectively, p = not significant). No grafts were lost from urinary complications. Renal function, as determined by the calculated creatinine clearance, was significantly greater in the pediatric group (76.1 +/- 4.0 versus 61.4 +/- 23.2 mL/min, p = 0.035) by 6 months after transplantation. Recipients of paired pediatric kidneys initially had better renal function (63.9 +/- 21.4 mL/min) than those receiving single pediatric kidneys (38.2 +/- 11.6 mL/min) (p = 0.004), but by 6 months, no significant difference existed. At 2 years, renal function in the pediatric-donor group remained significantly better than in the adult-donor group. Hematocrit levels as a measure of erythropoiesis were similar for single pediatric, paired pediatric, and adult-donor recipients. CONCLUSIONS: Kidneys from cadaveric donors < or = 5 years of age are suitable for transplantation into adults. Pediatric kidneys provide excellent renal function despite an initially tremendous disparity between renal mass and recipient body mass. Rapid true renal growth probably occurs. No appreciable advantage is achieved by using two pediatric kidneys for a single recipient.

CD20-positive infiltrates in renal allograft biopsies with acute cellular rejection are not associated with worse graft survival.

We examined rejection outcome and graft survival in 58 adult patients with acute cellular rejection Banff type I (ARI) or II (ARII), within 1 year after transplantation, with or without CD20-positive infiltrates. Antibody-mediated rejection was not examined. Of the 74 allograft biopsies, performed from 1999 to 2001, 40 biopsies showed ARI and 34 biopsies showed ARII; 30% of all the biopsies showed CD20-positive clusters with more than 100 cells, 9% with more than 200 cells and 5% with more than 275 cells. Patients with B cell-rich (>100 or >200/HPF CD20-positive cells) and B cell-poor biopsies (<50 CD20-positive cells/HPF) were compared. Serum creatinine and eGFR of B cell-rich (CD20 > 100/HPF) and B cell-poor were not significantly different at rejection, or at 1, 3, 6 and 12 months, and during additional 3 years follow-up after rejection, although higher creatinine at 1 year was noted in the >200/HPF group. Graft survival was also not different between B cell-rich and B cell-poor groups (p = 0.8 for >100/HPF, p = 0.9 for >200/HPF CD20-positive cells). Our data do not support association of B cell-rich infiltrates in allograft biopsies and worse outcome in acute rejection type I or II, but do not exclude the possible contribution of B cells to allograft rejection.

Subclinical acute antibody-mediated rejection in positive crossmatch renal allografts.

Subclinical antibody-mediated rejection (AMR) has been described in renal allograft recipients with stable serum creatinine (SCr), however whether this leads to development of chronic allograft nephropathy (CAN) remains unknown. We retrospectively reviewed data from 83 patients who received HLA-incompatible renal allografts following desensitization to remove donor-specific antibodies (DSA). Ten patients had an allograft biopsy showing subclinical AMR [stable SCr, neutrophil margination in peritubular capillaries (PTC), diffuse PTC C4d, positive DSA] during the first year post-transplantation; 3 patients were treated with plasmapheresis and intravenous immunoglobulin. Three patients had a subsequent rise in SCr and an associated biopsy with AMR; 5 others showed diagnostic or possible subclinical AMR on a later protocol biopsy. One graft was lost, while remaining patients have normal or mildly elevated SCr 8-45 months post-transplantation. However, the mean increase in CAN score (cg + ci + ct + cv) from those biopsies showing subclinical AMR to follow-up biopsies 335 +/- 248 (SD) days later was significantly greater (3.5 +/- 2.5 versus 1.0 +/- 2.0, p = 0.01) than that in 24 recipients of HLA-incompatible grafts with no AMR over a similar interval (360 +/- 117 days), suggesting that subclinical AMR may contribute to development of CAN.

C4d and C3d staining in biopsies of ABO- and HLA-incompatible renal allografts: correlation with histologic findings.

Biopsies of ABO-incompatible and positive crossmatch (HLA-incompatible) renal allografts were retrospectively examined to compare results of C4d and C3d staining, and the correlation between such staining and histologic findings suggestive of antibody-mediated rejection (AMR). A total of 75 biopsies (55 protocol, 17 for graft dysfunction, 3 for other indications) of 24 ABO-incompatible grafts and 244 biopsies (103 protocol, 129 for graft dysfunction, 12 for other indications) of 66 HLA-incompatible grafts were examined; all were stained for C4d and approximately 40% for C3d. In ABO-incompatible grafts, 80% of protocol biopsies and 59% performed for graft dysfunction showed C4d staining in peritubular capillaries (PTC); this staining was not correlated with neutrophil margination in PTC. In HLA-incompatible grafts, PTC C4d was present in 26% of protocol biopsies and 60% of biopsies for graft dysfunction; 92% of biopsies with >1+ (0-4+ scale), diffuse PTC C4d had > or =1+ margination and/or thrombotic microangiopathy (TMA), compared with 12% of C4d-negative biopsies. C3d was somewhat more predictive of margination than C4d in ABO-incompatible, but not HLA-incompatible, grafts. In summary, while PTC C4d deposition indicates probable AMR in biopsies of HLA-incompatible grafts, including protocol biopsies, there is no histologic evidence that C4d deposition is correlated with injury in most ABO-incompatible grafts.

Pure red cell aplasia caused by Parvovirus B19 infection in solid organ transplant recipients: a case report and review of literature.

Human Parvovirus B19 (PV B19) is one of the several recently described 'emerging viruses' and has been identified as the etiological agent of 'fifth disease' in childhood. Human PV B19, which is the etiological agent of transient erythroblastopenia in hemolytic anemia, is also a recognized rare cause of red cell aplasia in immunocompromised patients, including transplant recipients. To date, 26 cases of PV B19-induced red cell aplasia have been reported in solid organ transplant recipients. Twelve patients had cyclosporine-based immunosuppression and 14 had tacrolimus-based immunosuppression. Sixteen of these patients required treatment with commercial intravenous immunoglobulin alone, 1 required treatment with intravenous immunoglobulin and plasmapheresis, 4 required intravenous immunoglobulin and erythropoietin, 1 required treatment with intravenous immunoglobulin and conversion of tacrolimus to cyclosporine, 1 had improvement in hematocrit with erythropoietin alone and in 3 patients the disease was self-limiting. Herein, we report a case of pure red cell aplasia caused by acute PV B19 infection in a renal transplant recipient in whom the immunosuppressive regimen included prednisone, mycophenolate mofetil and tacrolimus and the red cell aplasia resolved with discontinuation of mycophenolate mofetil.

Effect of phosphorus restriction on renal response to oral and intravenous protein loads in rats.

Dietary phosphorus restriction ameliorates renal injury in rats. This may be due to changes in renal hemodynamics, including those factors associated with protein-induced hyperfiltration. To test this, we measured inulin clearance (CIn), p-aminohippuric acid clearance (CPAH), mean arterial blood pressure, and renal vascular resistance (RVR) 1 h before and 100 min after either oral gavage of 2 g bovine serum albumin or intravenous infusion of 5% glycine in female Sprague-Dawley rats previously fed for 3-8 wk a 0.5% or a 0.1% phosphorus diet. Baseline CIn, CPAH, blood pressure, and RVR were similar. After albumin gavage, CIn rose 20% (P < 0.01) for the 0.5% phosphorus group but did not change for rats fed the 0.1% phosphorus diet. Other measured parameters, including plasma glucagon and renin activity, were not influenced by dietary phosphorus content. In contrast, during intravenous infusion of glycine, hyperfiltration was induced in phosphorus-restricted rats. Thus dietary phosphorus restriction ablates oral protein but not intravenous amino acid-induced hyperfiltration, suggesting a gut-mediated mechanism for the former. These data highlight the potential importance of dietary phosphorus as a mediator of renal hemodynamics.

Shorter waiting times for hepatitis C virus seropositive recipients of cadaveric renal allografts from hepatitis C virus seropositive donors.

INTRODUCTION: The purposes of this study were: 1) to analyze the early results of cadaveric renal transplantation from either hepatitis C virus seropositive (HCV+ ) or hepatitis C virus seronegative (HCV-) donors into HCV + recipients; and 2) to determine whether HCV+ patients with end-stage renal disease (ESRD) might benefit from receiving renal allografts from HCV + donors. METHODS: From January 1997 to June 1999, 28 patients with ESRD and HCV infection underwent 29 cadaveric renal transplants. The data were reviewed retrospectively. Nineteen of the renal transplants were performed with allografts obtained from 15 HCV + donors and 10 with allografts obtained from 10 HCV- donors. The median follow-up was 16.2 months, with an average of 15.4+/-2 months. RESULTS: Recipients of HCV + renal allografts had shorter waiting times for transplantation. On average, patients who received a kidney from HCV + donors were transplanted 9+/-3 months after being placed on the transplant list, compared to 29+/-3 months for patients who received a kidney from a HCV- donor. Shorter waiting times were noted in every blood type group. There were no significant differences in rejection episodes, infectious complications, renal function, liver function, graft survival, or patient survival. CONCLUSIONS: The use of renal allografts from HCV + donors for HCV + recipients shortens the waiting time for these patients, with no short-term differences in renal and liver function, graft loss, or patient survival.

Analysis of immune status of hemodialyzed adults: association with prior transfusions.

Peripheral blood leukocytes of 29 hemodialyzed adults, 19 transfused and 10 nontransfused, were studied using immunofluorescent staining with monoclonal antibodies and in vitro measurement of natural killer (NK) cell activity. When compared with control subjects, the absolute number of leukocytes in transfused hemodialyzed patients was significantly reduced (P less than 0.01), as were the absolute numbers of OKT11+ cells (P less than 0.01), and OKT4+ cells (P less than 0.0001). The percent representation of OKT11+ and OKT4+ cells was also significantly lower among transfused hemodialyzed patients (P less than 0.01 and 0.001, respectively), and this loss of OKT4+ cells resulted in a decrease in the ratio of OKT4+/OKT8+ cells (P less than 0.01). The absolute number of Leu-7+ cells was also decreased in the transfused group (P less than 0.05). A decrease in in vitro NK cell activity was present in both transfused and nontransfused hemodialyzed subjects. Whether these differences in peripheral blood lymphocytes were induced by the erythrocyte transfusions could not be determined; however, if they reflect changes in central lymphoid tissues, then these results may help explain the prolonged survival of renal allografts in transfused individuals.