Differential effects of donor-specific HLA antibodies in living versus deceased donor transplant.

The presence of donor-specific anti-HLA antibodies (DSAs) is associated with increased risk of graft failure after kidney transplant. We hypothesized that DSAs against HLA class I, class II, or both classes indicate a different risk for graft loss between deceased and living donor transplant. In this study, we investigated the impact of pretransplant DSAs, by using single antigen bead assays, on long-term graft survival in 3237 deceased and 1487 living donor kidney transplants with a negative complement-dependent crossmatch. In living donor transplants, we found a limited effect on graft survival of DSAs against class I or II antigens after transplant. Class I and II DSAs combined resulted in decreased 10-year graft survival (84% to 75%). In contrast, after deceased donor transplant, patients with class I or class II DSAs had a 10-year graft survival of 59% and 60%, respectively, both significantly lower than the survival for patients without DSAs (76%). The combination of class I and II DSAs resulted in a 10-year survival of 54% in deceased donor transplants. In conclusion, class I and II DSAs are a clear risk factor for graft loss in deceased donor transplants, while in living donor transplants, class I and II DSAs seem to be associated with an increased risk for graft failure, but this could not be assessed due to their low prevalence.

Early Conversion to Prednisolone/Everolimus as an Alternative Weaning Regimen Associates With Beneficial Renal Transplant Histology and Function: The Randomized-Controlled MECANO Trial.

In renal transplantation, use of calcineurin inhibitors (CNIs) is associated with nephrotoxicity and immunosuppression with malignancies and infections. This trial aimed to minimize CNI exposure and total immunosuppression while maintaining efficacy. We performed a randomized controlled, open-label multicenter trial with early cyclosporine A (CsA) elimination. Patients started with basiliximab, prednisolone (P), mycophenolate sodium (MPS), and CsA. At 6 months, immunosuppression was tapered to P/CsA, P/MPS, or P/everolimus (EVL). Primary outcomes were renal fibrosis and inflammation. Secondary outcomes were estimated glomerular filtration rate (eGFR) and incidence of rejection at 24 months. The P/MPS arm was prematurely halted. The trial continued with P/CsA (N = 89) and P/EVL (N = 96). Interstitial fibrosis and inflammation were significantly decreased and the eGFR was significantly higher in the P/EVL arm. Cumulative rejection rates were 13% (P/EVL) and 19% (P/CsA), (p = 0.08). A post hoc analysis of HLA and donor-specific antibodies at 1 year after transplantation revealed no differences. An individualized immunosuppressive strategy of early CNI elimination to dual therapy with everolimus was associated with decreased allograft fibrosis, preserved allograft function, and good efficacy, but also with more serious adverse events and discontinuation. This can be a valuable alternative regimen in patients suffering from CNI toxicity.

How can we reduce costs of solid-phase multiplex-bead assays used to determine anti-HLA antibodies?

Solid-phase multiplex-bead assays are widely used in transplantation to detect anti-human leukocyte antigen (HLA) antibodies. These assays enable high resolution detection of low levels of HLA antibodies. However, multiplex-bead assays are costly and yield variable measurements that limit the comparison of results between laboratories. In the context of a Dutch national Consortium study we aimed to determine the inter-assay and inter-machine variability of multiplex-bead assays, and we assessed how to reduce the assay reagents costs. Fifteen sera containing a variety of HLA antibodies were used yielding in total 7092 median fluorescence intensities (MFI) values. The inter-assay and inter-machine mean absolute relative differences (MARD) of the screening assay were 12% and 13%, respectively. The single antigen bead (SAB) inter-assay MARD was comparable, but showed a higher lot-to-lot variability. Reduction of screening assay reagents to 50% or 40% of manufacturers' recommendations resulted in MFI values comparable to 100% of the reagents, with an MARD of 12% or 14%, respectively. The MARD of the 50% and 40% SAB assay reagent reductions were 11% and 22%, respectively. From this study, we conclude that the reagents can be reliably reduced at least to 50% of manufacturers' recommendations with virtually no differences in HLA antibody assignments.

Incidence, risk factors, and the impact of allograft pyelonephritis on renal allograft function.

BACKGROUND: The impact of allograft pyelonephritis (AGPN) on renal allograft function is controversial. In this study, we evaluated the incidence, risk factors, and the impact of AGPN on renal allograft function. METHODS: Retrospective cohort study in adult renal allograft recipients with 1-year follow-up after transplantation (Tx). Renal allograft function was evaluated by estimated glomerular filtration rate (eGFR) (by Modification of Diet in Renal Disease formula) and 24-h urine protein excretion. RESULTS: A total of 431 renal allograft recipients were analyzed; 57 (13.2%) developed AGPN within 1 year after Tx. Median time between Tx and AGPN was 50 days. Risk factors for AGPN were the presence of a urological catheter (odds ratio [OR] = 18.93, 95% confidence interval [CI] = 8.00-44.81, P < 0.001) and preceding asymptomatic bacteriuria (ASB) (OR = 2.16, 95% CI = 1.20-3.90, P = 0.009). In 72.7%, the causative microorganism of ASB was identical to that of the succeeding AGPN episode. Multivariable linear regression analysis showed that experiencing AGPN did not decrease the eGFR (P = 0.61) nor did increased proteinuria (P = 0.29) 1 year after Tx. For the eGFR, an interaction was found between AGPN/bacteriuria (BU) and acute rejection (AR): the group experiencing BU preceding AR had significantly (P < 0.001) lower eGFR compared with the group that experienced only AR (21 mL/min/1.73 m2 vs. 48 mL/min/1.73 m2 ), as a result of increased prevalence of combined rejections within the BU group. CONCLUSION: Indwelling urological catheters and preceding ASB are associated with developing AGPN. An incident of AGPN itself does not impair renal allograft function 1 year after Tx. However, a relevant interaction occurs between BU and AR, in which the sequence of occurrence of these 2 events synergistically impairs the eGFR.

17D yellow fever vaccine elicits comparable long-term immune responses in healthy individuals and immune-compromised patients.

BACKGROUND: The 17D live attenuated yellow fever (YF) vaccine is contra-indicated in immune-compromised individuals and may elicit a suboptimal immunologic response. The aim of this study is to assess whether long-term immune responses against the YF vaccine are impaired in immune-compromised patients. MATERIALS AND METHODS: Fifteen patients using different immunosuppressive drugs and 30 healthy individuals vaccinated 0-22 years ago were included. The serological response was measured using the plaque reduction neutralization test (PRNT). CD8(+) and CD4(+) T-cell responses were measured following proliferation and re-stimulation with YFV peptide pools. Phenotypic characteristics and cytokine responses of CD8(+) T-cells were determined using class I tetramers. RESULTS: The geometric mean titre of neutralizing antibodies was not different between the groups (p = 0.77). The presence of YFV-specific CD4(+) and CD8(+) T-cell did not differ between patients and healthy individuals (15/15, 100.0% vs. 29/30, 96.7%, p = 0.475). Time since vaccination correlated negatively with the number of YFV-specific CD8(+) T-cells (r = -0.66, p = 0.0045). Percentages of early-differentiated memory cells increased (r = 0.67, p = 0.017) over time. CONCLUSION: These results imply that YF vaccination is effective despite certain immunosuppressive drug regimens. An early-differentiated memory-like phenotype persisted, which is associated with effective expansion upon re-encounter with antigen, suggesting a potent memory T-cell pool remains.

Virus-Specific CD8(+) T Cells Cross-Reactive to Donor-Alloantigen Are Transiently Present in the Circulation of Kidney Transplant Recipients Infected With CMV and/or EBV.

T cells play a dual role in transplantation: They mediate transplant rejection and are crucial for virus control. Memory T cells generated in response to pathogens can cross-react to alloantigen, a phenomenon called heterologous immunity. Virus-specific CD8(+) T cells cross-reacting to donor-alloantigen might affect alloimmune responses and hamper tolerance induction following transplantation. Here, we longitudinally studied these cross-reactive cells in peripheral blood of 25 kidney transplant recipients with a cytomegalovirus and/or Epstein-Barr virus infection. Cross-reactive T cells were identified by flow cytometry as virus-specific T cells that proliferate in response to donor cells in a mixed-lymphocyte reaction. In 13 of 25 patients, we found cross-reactivity to donor cells for at least 1 viral epitope before (n = 7) and/or after transplantation (n = 8). Cross-reactive T cells were transiently present in the circulation, and their precursor frequency did not increase following transplantation or viral infection. Cross-reactive T cells expressed interferon-γ and CD107a in response to both alloantigen and viral peptide and resembled virus-specific T cells in phenotype and function. Their presence was not associated with impaired renal function, proteinuria, or rejection. In conclusion, virus-specific T cells that cross-react to donor-alloantigen are transiently detectable in the circulation of kidney transplant recipients.

Immunization after renal transplantation: current clinical practice.

BACKGROUND: The use of potent immunosuppressive drugs and increased travel by renal transplant recipients (RTR) has augmented the risk for infectious complications. Immunizations and changes in lifestyle are protective. The Kidney Disease: Improving Global Outcomes (KDIGO) Transplant Work Group has developed guidelines on vaccination following solid organ transplantation. The degree of adherence to these guidelines is unknown, as is which barriers must be overcome to improve adherence. METHODS: We performed a cross-sectional national survey among Dutch nephrologists to assess vaccination policy and adherence to the KDIGO guidelines. In addition, to investigate awareness and attitude of RTR regarding their risk of infection, we performed a cross-sectional survey of RTR in our outpatient clinic. RESULTS: A total of 132 (63%) nephrologists completed the survey. Reported immunization rates were 90.8% for influenza and 27.3% for hepatitis B. However, pneumococcal, tetanus toxoid, and meningococcal immunization rates were low. Twenty-seven percent of respondents were familiar with the guideline contents. The most frequent perceived barrier to guideline adherence was expectation of low effectiveness. A total of 403 RTR (62%) completed the survey. Sixty-eight percent perceived more risk for complicated infection. A significant correlation was found between education level and variables concerning awareness and attitude toward risk of infection. CONCLUSIONS: Our results show that nephrologists' knowledge of and adherence to the recommendations regarding immunization after renal transplantation is suboptimal. Most Dutch RTR are aware of their increased risk and the possible seriousness of infectious complications. However, their behavior does not match their awareness. This disparity points to an important role for nephrologists in providing adequate counseling.

Primary immunodeficiencies in the Netherlands: national patient data demonstrate the increased risk of malignancy.

PURPOSE: To analyze the data of the national registry of all Dutch primary immune deficiency (PID) patients, according to the European Society for Immunodeficiencies (ESID) definitions. RESULTS: In the Netherlands, 745 patients had been registered between 2009 and 2012. An overall prevalence of 4.0 per 100,000 inhabitants was calculated. The most prevalent PID was 'predominantly antibody disorder (PAD)' (60.4%). In total, 118 transplantations were reported, mostly hematopoietic stem cell transplantations (HSCT). Almost 10% of the PID patients suffered from a malignancy, in particular 'lymphoma' and 'skin cancer'. Compared to the general Dutch population, the relative risk of developing any malignancy was 2.3-fold increased, with a >10-fold increase for some solid tumors (thymus, endocrine organs) and hematological disease (lymphoma, leukemia), varying per disease category. CONCLUSIONS: The incidence rate and characteristics of PID in the Netherlands are similar to those in other European countries. Compared to the general population, PID patients carry an increased risk to develop a malignancy.

The potential beneficial role of faecal microbiota transplantation in diseases other than Clostridium difficile infection.

This review gives an outline of the indications for faecal microbiota transplantation (FMT) for diseases other than Clostridium difficile (C. difficile) infection. The remarkable efficacy of FMT against C. difficile infection has already been demonstrated. The use of FMT for other diseases, such as inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), and metabolic syndrome, is now being evaluated. The currently available data suggest that FMT might be beneficial for IBD (including ulcerative colitis and, to some extent, Crohn's disease), IBS, and insulin resistance. Several randomized clinical trials are currently being performed, and data are eagerly awaited. A new field of research for the implementation of FMT is the eradication of pathogenic and multiresistant enteric microorganisms. A few animal studies have been performed within this field, but hardly any research data from human studies are available at present.

The PROCARE consortium: toward an improved allocation strategy for kidney allografts.

Kidney transplantation is the best treatment option for patients with end-stage renal failure. At present, approximately 800 Dutch patients are registered on the active waiting list of Eurotransplant. The waiting time in the Netherlands for a kidney from a deceased donor is on average between 3 and 4 years. During this period, patients are fully dependent on dialysis, which replaces only partly the renal function, whereas the quality of life is limited. Mortality among patients on the waiting list is high. In order to increase the number of kidney donors, several initiatives have been undertaken by the Dutch Kidney Foundation including national calls for donor registration and providing information on organ donation and kidney transplantation. The aim of the national PROCARE consortium is to develop improved matching algorithms that will lead to a prolonged survival of transplanted donor kidneys and a reduced HLA immunization. The latter will positively affect the waiting time for a retransplantation. The present algorithm for allocation is among others based on matching for HLA antigens, which were originally defined by antibodies using serological typing techniques. However, several studies suggest that this algorithm needs adaptation and that other immune parameters which are currently not included may assist in improving graft survival rates. We will employ a multicenter-based evaluation on 5429 patients transplanted between 1995 and 2005 in the Netherlands. The association between key clinical endpoints and selected laboratory defined parameters will be examined, including Luminex-defined HLA antibody specificities, T and B cell epitopes recognized on the mismatched HLA antigens, non-HLA antibodies, and also polymorphisms in complement and Fc receptors functionally associated with effector functions of anti-graft antibodies. From these data, key parameters determining the success of kidney transplantation will be identified which will lead to the identification of additional parameters to be included in future matching algorithms aiming to extend survival of transplanted kidneys and to diminish HLA immunization. Computer simulation studies will reveal the number of patients having a direct benefit from improved matching, the effect on shortening of the waiting list, and the decrease in waiting time.

Antibody response to a T-cell-independent antigen is preserved after splenic artery embolization for trauma.

Splenic artery embolization (SAE) is increasingly being used as a nonoperative management strategy for patients with blunt splenic injury following trauma. The aim of this study was to assess the splenic function of patients who were embolized. A clinical study was performed, with splenic function assessed by examining the antibody response to polysaccharide antigens (pneumococcal 23-valent polysaccharide vaccine), B-cell subsets, and the presence of Howell-Jolly bodies (HJB). The data were compared to those obtained from splenectomized patients and healthy controls (HC) who had been included in a previously conducted study. A total of 30 patients were studied: 5 who had proximal SAE, 7 who had distal SAE, 8 who had a splenectomy, and 10 HC. The median vaccine-specific antibody response of the SAE patients (fold increase, 3.97) did not differ significantly from that of the HC (5.29; P = 0.90); however, the median response of the splenectomized patients (2.30) did differ (P = 0.003). In 2 of the proximally embolized patients and none of the distally embolized patients, the ratio of the IgG antibody level postvaccination compared to that prevaccination was <2. There were no significant differences in the absolute numbers of lymphocytes or B-cell subsets between the SAE patients and the HC. HJB were not observed in the SAE patients. The splenic immune function of embolized patients was preserved, and therefore routine vaccination appears not to be indicated. Although the median antibody responses did not differ between the patients who underwent proximal SAE and those who underwent distal SAE, 2 of the 5 proximally embolized patients had insufficient responses to vaccination, whereas none of the distally embolized patients exhibited an insufficient response. Further research should be done to confirm this finding.

Treatment efficacy of hypertension in kidney transplant recipients in the Netherlands.

BACKGROUND: Hypertension in kidney transplant recipients jeopardises graft and patient survival. Guidelines suggest blood pressure targets of ≤130/80 mmHg and sodium intake <90 mmol/day. METHODS: Since the efficacy of antihypertensive treatment among kidney transplant recipients is unknown, we analysed data on office-based blood pressure and use of antihypertensive drugs from the Netherlands Organ Transplant Registry on 5415 kidney transplant recipients. Additionally, we studied dosages, prevalence of treatment-resistant hypertension and 24-hour sodium excretion in 534 kidney transplant recipients from our centre to explore possibilities for therapy optimisation. RESULTS: In patients registered in the Netherlands Organ Transplant Registry, median blood pressure was 134/80 mmHg (interquartile range 122-145/70-85). In 77.2%, the blood pressure was ≥130/80 mmHg; of these patients 10.4% had no registered use, 30.0% used one and 25.9% used ≥3 classes of antihypertensive agents. Parameters from our centre were comparable: 78.7% had a median blood pressure of ≥130/80 mmHg of whom 14.5% had no registered use of antihypertensives and 26.4% used ≥3 classes. Sub-maximal dosages were prescribed in 74.0% of the kidney transplant recipients with a blood pressure of ≥130/80 mmHg while using at least one antihypertensive agent. Treatment-resistant hypertension was present in 7.7%. Median 24-hour sodium excretion was 147 mmol/day (interquartile range 109-195). CONCLUSIONS: This study suggests that therapeutic optimisation of antihypertensive treatment in kidney transplant recipients is, in theory, frequently possible by intensifying pharmacological treatment and by providing more advice on dietary sodium restrictions.

Immunosuppressive drugs after solid organ transplantation.

In recent years solid organ transplantation has been rapidly developed as a therapeutic intervention that is life-saving and greatly contributes to a better quality of life in organ recipients. The rapid development has been made possible because of a drastic expansion in the immunosuppressive repertoire. Unfortunately, the side effects of these drugs can be severe, which is one of the reasons that life expectancy of transplant patients still significantly falls short of that of the general population. In this review manuscript we will discuss current and future immunosuppressive strategies that are employed in solid organ transplantation. Expanding our understanding of the human immune system will hopefully provide us with newer, smarter drugs that promote immunotolerance without the side effects observed today.

A single dose of rituximab does not deplete B cells in secondary lymphoid organs but alters phenotype and function.

A single dose of the anti-CD20 monoclonal antibody rituximab induces a nearly complete B cell depletion in peripheral blood, but not in secondary lymphoid organs. Modulation of this remaining B cell population due to rituximab treatment may contribute to the therapeutic effects of rituximab. To assess the in vivo effects of rituximab we used lymph nodes (LNs) collected during renal transplant surgery in patients who had received rituximab 4 weeks earlier in preparation for an ABO-incompatible transplantation. Rituximab treatment resulted in a lower percentage of naïve (IgD(+)CD27(-)) and a higher percentage of switched memory (IgD(-)CD27(+)) B cells. Remarkably, transitional (CD24(++)CD38(++)) B cells were virtually lacking in the LNs of rituximab-treated patients. Moreover, LN-derived B cells from rituximab-treated patients produced different amounts of various Ig-subclasses after anti-CD40/IL-21 stimulation ex vivo. Finally, after stimulation of allogeneic T cells with LN-derived B cells from rituximab-treated patients, the proliferated T cells showed a decreased production of IL-17. In conclusion, after treatment with rituximab there remains a B cell population with different functional capacities. Consequently, the effect of rituximab on the immune response will not only be determined by the extent of B cell depletion, but also by the functional properties of the remaining B cells.

First clinical experience with polysol solution: pilot study in living kidney transplantation.

In this study, we assessed the safety of the new organ preservation solution polysol solution in the clinical setting of living kidney transplantation. We conducted a prospective pilot study in nine adult donor-recipient couples using polysol solution for washout and cold storage of kidney grafts. Adverse reactions possibly related to the use of polysol solution as well as renal function at 1, 6, and 12 months after transplantation were monitored. All living kidney transplantation performed in adults in our center within 2002 to 2008 using the University of Winconsin solution served as controls (n = 190). The use of polysol solution was associated with a higher acute rejection rate compared to University of Wisconsin solution at all time points. Also, antibody-mediated rejection occurred more frequently in the polysol group. Renal function at all time points was also comparable between the groups. This pilot study in living kidney transplantation is the first clinical study on the use of polysol solution. Although the study was not powered on the endpoint rejection, we observed a high number of acute rejection and antibody-mediated rejection episodes in recipients of polysol solution preserved grafts as compared to University of Wisconsin solution controls. As a consequence the study was terminated prematurely.

Polyomavirus BK in the pathogenesis of bladder cancer.

Polyomaviruses are able to drive malignant transformation in rodent models, and have been implicated in the aetiology of a variety of human malignancies. However, the reports on this association in humans are strongly conflicting. Here we describe a renal transplant (RT) recipient with ureteral stenosis against the background of polyomavirus BK (BKV) activity. Six and a half years after transplantation, this patient developed metastasised bladder cancer. Prior to the diagnosis of cancer, atypical cells were detected in the urine that were denoted as 'decoy cells': virally infected epithelial cells that are frequently seen in the urine of RT recipients with BKV (re)activation, which may morphologically resemble malignant cells. Intriguingly, the primary urothelial carcinoma, as well as the mesenterial and two intestinal metastases, stained positive with antibodies against polyomavirus virus large T antigen protein, whereas the adjacent healthy tissue did not. This case suggests a role for BKV in the pathogenesis of bladder cancer, at least in the context of immunodeficiency.