Andrew Bentall

Five‐Year Outcomes in Living Donor Kidney Transplants With a Positive Crossmatch

Renal transplant candidates with high levels of donor‐specific anti‐HLA antibodies have low transplantation rates and high mortality rates on dialysis. Using desensitization protocols, good short‐term outcomes are possible in “positive crossmatch kidney transplants (+XMKTx)”, but long‐term outcome data are lacking. The aim of the current study was to determine actual 5‐year graft outcomes of +XMKTx. We compared graft survival and the functional and histologic status of 102 +XMKTx to 204 −XMKTx matched for age and sex. Actual 5‐year death‐censored graft survival was lower in the +XMKTx group (70.7% vs. 88.0%, p < 0.01) and chronic injury (glomerulopathy) was present in 54.5% of surviving grafts. Graft survival was higher in recipients with antibody against donor class I only compared with antibody against class II (either alone or in combination with class I) (85.3% vs. 62.6%, p = 0.05) and was similar to −XMKTx (85.3 vs. 88.0%, p = 0.64). Renal function and proteinuria ranged across a wide spectrum in all groups reflecting the different histological findings at 5 years. We conclude that when compared to −XMKTx, +XMKTx have inferior outcomes at 5 years, however, almost half of the surviving grafts do not have glomerulopathy and avoiding antibodies against donor class II may improve outcomes.

Antibody-mediated rejection despite inhibition of terminal complement

Terminal complement blockade has been shown to decrease the incidence of early acute antibody‐mediated rejection (eAMR) in the first month after positive cross‐match kidney transplant recipients, yet some patients still develop eAMR. The current study investigated possible mechanisms of eAMR despite eculizumab treatment. Of the 26 patients treated with eculizumab, two developed clinical eAMR and another patient developed histologic signs of eAMR without graft dysfunction (‘subclinical eAMR’). Twenty‐three did not have histologic injury on early surveillance biopsies. All 26 patients had therapeutic levels of eculizumab and showed complete blockade of complement in hemolytic assays. High levels of donor‐specific alloantibody (DSA) including total IgG, IgG3, and C1q+ DSA were present in patients with and without eAMR, and none correlated well with eAMR. In contrast, IgM DSA was present in only four patients after transplantation: the two patients with clinical eAMR, one patient with subclinical AMR, and one patient without eAMR (P = 0.006 correlation with eAMR). Both clinical eAMR episodes were easily treated with plasma exchange which removed IgM more completely and rapidly than IgG, resulting in normalization of function and histology. These data suggest a possible role of antidonor IgM DSA in the pathogenesis of eAMR in patients treated with terminal complement blockade (ClinicalTrials.gov Identifier: NCT00670774).

Assessing and comparing rival definitions of delayed renal allograft function for predicting subsequent graft failure.

Background. The traditional definition of delayed graft function (DGF) rests on dialysis requirement during the first postoperative week. Subsequently, a more objective and “functional” definition of DGF (fDGF) has been proposed as an alternative to this dialysis-based definition of DGF (dDGF) and defined as a failure of the serum creatinine to decrease by at least 10% daily on 3 successive days during the first week posttransplantation, irrespective of dialysis requirement. However, an association between fDGF and long-term graft failure has not been fully established, and it is unknown whether fDGF is a better marker of subsequent outcomes than dDGF. Methods. We studied 750 adult deceased donor kidney transplant recipients (1996–2006) and analyzed the association between these two DGF definitions and long-term graft outcome. Results. Univariable associations with death-censored graft failure were seen for both dDGF and fDGF (hazard ratio [HR] 1.59; 95% confidence interval [CI] 1.16–2.18; P=0.004 and HR 1.72; 95% CI 1.26–2.36; P=0.001, respectively). On bivariable analysis (dDGF vs. fDGF), dDGF lost significance, whereas the effect of fDGF persisted (HR 1.52; 95%CI 1.03–2.25; P=0.04). This was also the case in a multivariable model, where fDGF but not dDGF was significantly associated with graft failure (HR 1.47; 95%CI 1.06–2.03; P=0.02). Results were similar for overall graft failure. Conclusions. This study confirms the utility of fDGF as an early marker of subsequent inferior allograft outcomes, suggesting superiority over the traditional (often subjective) dialysis-based definition. Wider adoption of the fDGF definition should be considered, both as a risk-stratification tool in clinical practice and a clinical trial endpoint.

Differences in chronic intragraft inflammation between positive crossmatch and ABO-incompatible kidney transplantation.

Background ABO-incompatible kidney transplantations (ABOiKTxs) seem to have better long-term outcomes than positive crossmatch kidney transplantations (+XMKTxs). Methods This study aimed to assess the differences in chronic injury on histologic findings on 1- and 5-year surveillance biopsies and the clinical outcomes in living-donor kidney transplantations performed between May 1999 and November 2006 including 102 +XMKTxs, 73 ABOiKTxs, and 652 conventional KTxs. Results Although 5-year patient survival was similar between groups, graft loss between 1 and 5 years was similar in ABOiKTx (2.6% per year) and conventional KTx (1.7% per yr), and both were lower than that of +XMKTx (5.8% per year). At 5 years, renal function was similar in ABOiKTx and conventional KTx, and both were higher than that of +XMKTx, which had higher rates of inflammation and chronic glomerulopathy on both 1- and 5-year biopsies. Despite having evidence of less chronic injury, ABOiKTx showed a higher rate of intragraft complement activation (C4d deposition) at 5 years compared with +XMKTx (77.8% vs. 18.9%, P<0.001). Conclusion These data suggest that +XMKTxs have high rates of chronic inflammation at 1 and 5 years after transplantation, which may explain the higher rates of graft loss and lower renal function compared with other factors such as anti–donor antibody or intragraft complement deposition.

ABO-incompatible kidney transplantation is a novel risk factor for BK nephropathy.

Variable ABOi BKVAN+ (n = 6) ABOi BKVAN− (n = 53) P A link between ABO-incompatible kidney transplantation and the risk of BK virus allograft nephropathy (BKVAN) has been identified in a report from JohnsHopkins Hospital. The 11 (17.7%) of 62 cases of BKVAN were identified by protocol (n = 5) or indication (n = 6) biopsies. The incidence of BKVAN in HLA–incompatible allograft recipients (transplantation after the removal of donor-specific HLA antibodies) and compatible allograft recipients was 5.9% and 3.0%, respectively. In a multivariable analysis, ABO-incompatible kidney transplantation was identified as an independent risk factor for the development of BKVAN. To date, no other report has corroborated this apparent overrepresentation of BKVAN in ABO-incompatible kidney transplant recipients. Between 2007 and 2013 with a median follow-up of 46.7 months (22.9–57.9), 59 ABO-incompatible kidney transplantations have been performed using antigenspecific immunoadsorption and rituximab induction (more recently basiliximab alone) at our center. Maintenance immunosuppression consists of tacrolimus, mycophenolate mofetil, and corticosteroids. In this cohort, 6 cases of BKVAN have been diagnosed on indication biopsy in the context of allograft dysfunction (10.2%, diagnosed 3–11 months after transplantation; Table 1). This incidence is similar to the indication biopsy cohort at Johns Hopkins Hospital and significantly greater than the frequency of detection in contemporaneous blood group–compatible transplants at our center (10.2% vs 3.2%, respectively, P = 0.014). In those with BKVAN, there is an overrepresentation of donor blood group B (5/6 vs 16/53, P = 0.018) and lower

T Lymphocyte responses to nonpolymorphic HLA-derived peptides are associated with chronic renal allograft dysfunction.

Background. The routine assessment of cellular alloimmunity to guide therapy is of perennial interest because this limb of the immune system is the main target of current transplant immunosuppression. That this has not as yet been realized in clinical practice reflects the difficulty of developing a standardized assay that accounts for the high degree of polymorphism exhibited by histocompatibility antigens. Methods. We have investigated whether immune responses to peptides derived from nonpolymorphic regions of human leukocyte antigen arise after transplantation, in particular in those with chronic allograft dysfunction. Results. Peripheral blood mononuclear cell &ggr;-interferon production to peptides derived from the nonpolymorphic &agr;3 domain of class 1 human leukocyte antigen occurred more frequently in long-term renal transplant recipients than healthy controls (51/110 vs. 1/18, 46.3% vs. 5.5%; P<0.001). These responses were associated with chronic allograft dysfunction manifested by a reduced and decreasing estimated glomerular filtration rate (responders vs. nonresponders: 39.5 vs. 48.8 mL/min, P=0.015 and −4.1 vs. −1.3 mL/min/year, P=0.008). Responses occurred mostly to autologous, “cryptic self-epitopes” and arose from CD4+CD25HiCD127Hi T lymphocytes, which have been previously implicated in chronic rejection. Conclusion. These findings suggest a strategy for assessing cellular immune responses to transplantation antigens with potential for generalization.

No progress in ABO titer measurement: time to aim for a reference?

not performed, these could provide interesting information in future cases. Moreover, the presence of background immunosuppression related to the first transplant may create a favorable environment for intestinal engraftment on one hand and may increase the chance of early postoperative life-threatening infectious complications on the other, which represent a common cause of death in these patients. Lastly, from a regulatory perspective, the liver-first approach could potentially interfere with the current liver allocation algorithm and therefore require a more specific deliberation should this practice become more accepted. In conclusion, sequential split liver followed by isolated intestinal transplant was a safe and feasible approach in our experience and could represent a viable option when timing is crucial.

Chronic Graft Versus Host Disease Is Associated With an Immune Response to Autologous Human Leukocyte Antigen-Derived Peptides

Background. Chronic graft-versus-host disease (cGVHD) is a major complication of allogeneic bone marrow transplantation (BMT) the immunopathogenesis of which is not well understood. Humoral and cellular immunity are both implicated, patients express a range of autoantibodies, but the targets of cellular immunity are not well defined. Autologous human leukocyte antigen (HLA)-derived peptides constitute a significant proportion of the repertoire. Methods. We have investigated the response to HLA-derived peptides after allogeneic BMT using &ggr;-interferon enzyme-linked immunospot assay (ELISPOT). We also studied the release of this &ggr;-interferon by flow cytometry in a subgroup of responsive patients. Results. The peripheral blood mononuclear cell response was assessed by &ggr;-interferon ELISPOT in 42 BMT recipients (21 with cGVHD) and 30 healthy donors. Thirteen of 21 patients diagnosed with cGVHD responded to at least one HLA-derived peptide compared with 1 of 21 patients without cGVHD (62% vs. 5%, P<10−4) and 1 of 30 healthy donors. In all but one patient these peptides correspond with the sequences of autologous HLA. The median single peptide–specific response in ELISPOT was 43/106 peripheral blood mononuclear cells. In a subgroup studied by flow cytometry, &ggr;-interferon production to individual peptides occurred in 0.04% to 0.18% of CD4+ T lymphocytes. Conclusion. These observations identify HLA-derived peptides as targets of a cellular immune response in cGVHD.

Minimal effect of bortezomib in reducing anti-pig antibodies in human leukocyte antigen-sensitized patients: a pilot study

Bortezomib, a proteasome inhibitor used to treat multiple myeloma, has been administered (± plasma exchange ± intravenous immunoglobulin [IVIg]) in attempts to reduce antibodies against human leukocyte antigens (HLA) in sensitized patients undergoing organ transplantation. To our knowledge, bortezomib has not been investigated for its effect on natural anti‐pig antibodies. If bortezomib could reduce the production of anti‐pig antibodies, this would likely be beneficial to the outcome of pig organ grafts in primates.

Ultrastructural Changes in Lung Allografts: Endothelial Changes Correlate with Donor Specific Antibody and Antibody-Mediated Rejection

Introduction Antibody mediated rejection (AMR) is a well-recognised cause of allograft injury; however only recently there is a growing recognition in lung transplantation (LTx). Allograft dysfunction can be multifactorial and challenges with C4d stain interpretation and the lack of specificity of histological criteria account for some of the difficulties in diagnosing pulmonary AMR. Donor Specific Antibodies (DSA) target the endothelium. In fact, in renal transplantation, endothelial activation markers and early ultrastructural changes of the endothelium correlate with AMR. The aim of this study was to identify ultrastructural changes in the endothelium of lung allografts in the presence of DSA, with the intent of determining if prospective use of electron microscopy might be helpful in establishing a diagnosis of AMR in LTx recipients. Materials & Methods The LTx database was queried for cases of pulmonary AMR between 07/2009 & 09/2015. The ISHLT guidelines were used to categorise these cases into definite, probable & possible AMR. Retrospective ultrastructural studies were performed on all these biopsies- either fresh or paraffin embedded. Cases of acute cellular rejection (4) and normal lung (3) were evaluated as controls. The findings on ultrastructural examination were correlated with the presence of DSA & diagnosis of AMR using the Pearson’s chi-square test of statistical significance. Results & Discussion Eleven patients (male, 54.5%) were included in this study.Mean age was 53yrs. Three cases were combined lung & heart Tx. We identified 7 cases of AMR (1 definite, 1 probable & 5 possible). The median time from LTx to biopsy (bx) was 210 days, with median follow up of 1063 days. Bronchiolitis Obliterans Syndrome was diagnosed in 5 patients. Ultrastructural studies were performed on 10 AMR bxs (pt 6:2 bxs; pt 7:3 bxs; all other pts: 1bx each), 4 ACR bxs & 4 controls. The results are shown.The presence of DSA as well as the ISHLT diagnosis of AMR significantly correlated with endothelial swelling, cytoplasmic vacuolisation & septal edema (p<0.01; each). Septal infiltration by neutrophils was only identified in AMR cases, although it did not achieve statistical significance. Importantly, these differences were still significant when using resin or paraffin based samples for EM, allowing larger retrospective studies to be performed; although endothelial swelling & vacuolisation occurred in non-DSA paraffin samples with EM. Table. No title available. Table. No title available. Conclusion Donor specific anti-HLA antibodies are associated with endothelial injury of the allograft. Ultrastructural findings such as endothelial swelling & vacuolization help in diagnosing antibody mediated allograft injury. Although paraffin embedded biopsy material can be used for this purpose, it is not without limitations and larger prospective studies are needed to validate these findings. The effect of DSA on the endothelial pathways will be important in all solid organ transplantation.