Pretransplantation donor-recipient pair seroreactivity against BK polyomavirus predicts viremia and nephropathy after kidney transplantation

Kidney transplant donors are currently not implicated in predicting BK polyomavirus (BKPyV) infection in kidney transplant recipients. It has been postulated, however, that BKPyV infection originates from the kidney allograft. Since BKPyV-seroreactivity correlates with BKPyV-replication and, therefore, might mirror the infectious load, we investigated whether BKPyV-seroreactivity of the donor predicts viremia and BKPyV-associated nephropathy (BKPyVAN) in the recipient. In a retrospective cohort of 407 living kidney donor-recipient pairs pretransplantation donor and recipient sera were tested for BKPyV IgG-levels and correlated with the occurrence of recipient BKPyV viremia and BKPyVAN within one year posttransplantation. As such, donor BKPyV IgG-level was strongly associated with BKPyV viremia and BKPyVAN (p < 0.001), while recipient BKPyV-seroreactivity showed a non-significant inverse trend. Pairing of high BKPyV-seroreactive donors with low seroreactive recipients resulted in a 10-fold increased risk for BKPyV viremia (HR 10.1, 95% CI: 3.5 – 29.0, p < 0.001). In multivariate analysis, donor BKPyV-seroreactivity was the strongest pretransplantation factor associated with viremia (p < 0.001) and BKPyVAN (p = 0.007). The proportional relation between donor BKPyV-seroreactivity and recipient infection suggests that donor BKPyV-seroreactivity reflects the infectious load of the kidney allograft, and calls for the use of pretransplantation BKPyV-serological testing of (potential) donors and recipients (read more)

The Risk of Transplant Failure With HLA Mismatch in First Adult Kidney Allografts From Deceased Donors

Background: Since the beginning of the technology, there has been active debate about the role of human leucocyte antigen (HLA) matching in kidney allograft survival. Recent studies have reported diminishing importance of HLA matching, which have, in turn, been challenged by reports that suggest the continuing importance of these loci. Given the controversies, we examined the effect of HLA compatibility on kidney allograft survival by studying all first adult kidney transplants in the United States from a deceased donor.
Methods: Using the United Network for Organ Sharing data, we identified first deceased donor kidney transplants between October 1, 1987, and December 31, 2013. Recipients were classified by their number of HLA mismatches. Cox multivariate regression analyses adjusting for recipient and donor transplant characteristics were performed to determine the impact of HLA compatibility on kidney allograft survival.
Results: Study cohort included 189 141 first adult kidney alone transplants, with a total of 994 558 years of kidney allograft follow-up time. Analyses adjusted for recipient and donor characteristics demonstrated a 13% higher risk (hazard ratio, 1.13; 95% confidence interval, 1.06-1.21) with 1 mismatch and a 64% higher risk (hazard ratio, 1.64, 95% confidence interval, 1.56-1.73) with 6 mismatches. Dividing the mismatch categories into 27 ordered permutations, and testing their 57 within mismatch category differences, demonstrated that all but 1 were equal, independent of locus.
Conclusions: A significant linear relationship of hazard ratios was associated with HLA mismatch and affects allograft survival even during the recent periods of increasing success in renal transplantation (read more)

A reliable method for avoiding false negative results with Luminex single antigen beads; evidence of the prozone effect.

Luminex single antigen bead (SAB) assays have become an essential tool in monitoring the status of antibody to the Human Leucocyte Antigen (HLA) of patients both before and after transplantation. In addition SAB data is used to aid risk stratification to assess immunological risk of humoral rejection in solid organ transplantation (CTAG/BTAG guidelines). Increasingly laboratories are reporting false negative results at high antibody titre due to a prozone effect. Here we report a case study where the prozone effect led to a false negative antibody result that could have resulted in adverse outcome. We describe a method to reliably remove the prozone effect through heat inactivation and the addition of Ethylenediaminetetraacetic acid (EDTA) to the Luminex wash buffer (read more)

Flow Cytometry Crossmatch Reactivity With Pronase-Treated T Cells Induced by Non-HLA Autoantibodies in Human Immunodeficiency Virus-Infected Patients.

Pronase treatment is used in the flow cytometry crossmatch (FCXM) to prevent nonspecific antibody binding on B cells. However, we have observed unexpected positive results with pronase-treated T cells in human immunodeficiency virus (HIV)-infected patients. In this study, 25 HIV-infected patients without HLA antibodies were tested with pronase-treated and nontreated cells. HIV-positive sera were pretreated with reducing agents and preabsorbed with pronase-treated and nontreated T or B cells before crossmatching. All patients displayed FCXM reactivity with pronase-treated T cells but not with nontreated T cells. None of the patients exhibited FCXM reactivity with pronase-treated and nontreated B cells. These patients displayed FCXM reactivity with pronase-treated CD4+ and CD8+ T cells but not with their nontreated counterparts. Preabsorption with pronase-treated T cells reduced the T cell FCXM reactivity. Preabsorption with pronase-treated B cells or nontreated T and B cells did not have any effect on the T cell FCXM reactivity. Pretreatment with reducing agents did not affect the T cell FCXM reactivity. 15 of 21 HIV-infected kidney allograft recipients with pronase-treated T cell FCXM reactivity display long-term graft survival (1,193 ± 631 days). These data indicate that HIV-infected patients have nondeleterious autoantibodies recognizing cryptic epitopes exposed by pronase on T cells. (read more)

New Classification of Donation after Circulatory Death Donors Definitions and Terminology

In the face of a crisis in organ donation, the transplant community are increasingly utilising donation after circulatory death (DCD) donors. Over the last 10 years, with the increasing usage of DCD donors, we have seen the introduction in a number of new terms and definitions. We report the results of the 6th International Conference in Organ Donation held in Paris in 2013 and report a consensus agreement of an established expert European Working Group on the definitions and terminology regarding DCD donation, including refinement of the Maastricht definitions. This document forms part of a special series where recommendations are presented for uncontrolled and controlled DCD donation and organ specific guidelines for kidney, pancreas, liver and lung transplantation. An expert panel formed a consensus on definitions and terms aiming to establish consistent usage of terms in DCD donation (read more)

Deciphering IgM interference in IgG anti-HLA antibody detection with flow beads assays

In flow beads assays, the interference of IgM for IgG anti-HLA antibodies detection is not precisely understood. Using the screening flow beads assay for class I HLA antibodies, we analyzed the binding of two IgG mAbs, the anti-class I HLA W6/32 and an anti-beta-2-microglobulin, in the presence of an anti-beta-2-microglobulin IgM mAb. In neat serum, the IgM mAb impaired the detection of both IgG. In EDTA-treated serum, the interference was stronger for the anti-beta-2-microglobulin IgG than for W6/32, in agreement with the finding in surface plasmon resonance that this IgM competed with the anti-beta-2-microglobulin IgG but not with W6/32. The IgM interference was higher in neat than in EDTA-treated serum for both IgG mAbs. The IgM interference was also analyzed with class II single antigen flow beads and sera from two kidney recipients containing IgG and IgM donor specific antibodies. Anti-HLA IgG detection was partially corrected by EDTA, and restored by IgM inactivation with DTT, confirming the results observed with the mAbs. Therefore, three mechanisms can explain the IgM interference for IgG anti-HLA antibodies in flow beads assays: direct competition for antigen, steric hindrance and complement activation (read more)

Abdominal Wall Transplantation: A Sentinel Marker for Rejection

Abdominal wall (AW) transplantation (AWTX) has revolutionized difficult abdominal closure after intestinal transplantation (ITX). More importantly, the skin of the transplanted AW may serve as an immunological tool for differential diagnosis of bowel dysfunction post-transplant. Between 08/2008 and 10/2014, 29 small bowel transplantations were performed in 28 patients (16male;12female; 41±13years). Two groups were identified: The SOT (solid organ transplant)-group (n=15; 12ITX and 3MMVTX) and the SOT+AWTX-group (n=14; 12ITX and 2MMVTX), the latter included one ITX+AWTX retransplantation. Two doses of alemtuzumab were used for induction (30mg, 6 and 24hours post-reperfusion) and tacrolimus (trough levels 8–12ng/ml) was used for maintenance immunosuppression. Patient survival was similar in both groups (67%vs.61%). However, the SOT+AWTX-group showed faster post-transplant recovery, a better intestinal graft survival (79%vs.60%), a lower intestinal rejection rate (7%vs.27%) and a lower rate of misdiagnoses, where viral infection was mistaken and treated for rejection (14%vs.33%). The skin component of the AW may serve as an immune modulator and sentinel marker for immunological activity in the host. This can be a vital tool for timely prevention of intestinal graft rejection and more importantly avoidance of over-immunosuppression in cases of bowel dysfunction not related to graft rejection (read more).