Effect of panel-reactive antibody positivity on graft rejection before or after kidney transplantation

Panel-reactive Antibody and the Association of Early Steroid Withdrawal With Kidney Transplant Outcomes

BACKGROUND

Early steroid withdrawal (ESW) is a viable maintenance immunosuppression strategy in low-risk kidney transplant recipients. A low panel-reactive antibody (PRA) may indicate low-risk condition amenable to ESW. We aimed to identify the threshold value of PRA above which ESW may pose additional risk and to compare the association of ESW with transplant outcomes across PRA strata.

METHODS

We studied 121 699 deceased-donor kidney-only recipients in 2002-2017 from Scientific Registry of Transplant Recipients. Using natural splines and ESW-PRA interaction terms, we explored how the associations of ESW with transplant outcomes change with increasing PRA values and identified a threshold value for PRA. Then, we assessed whether PRA exceeding the threshold modified the associations of ESW with 1-y acute rejection, death-censored graft failure, and death.

RESULTS

The association of ESW with acute rejection exacerbated rapidly when PRA exceeded 60. Among PRA ≤60 recipients, ESW was associated with a minor increase in rejection (adjusted odds ratio [aOR], 1.001.051.10) and with a tendency of decreased graft failure (adjusted hazard ratio [aHR], 0.910.971.03). However, among PRA >60 recipients, ESW was associated with a substantial increase in rejection (aOR, 1.191.271.36; interaction P < 0.001) and with a tendency of increased graft failure (aHR, 0.981.081.20; interaction P = 0.028). The association of ESW with death was similar between PRA strata (PRA ≤60, aHR, 0.910.961.01; and PRA >60, aHR, 0.900.991.09; interaction P = 0.5).

CONCLUSIONS

Our findings show that the association of ESW with transplant outcomes is less favorable in recipients with higher PRA, especially those with PRA >60, suggesting a possible role of PRA in the risk assessment for ESW.

Use of Panel-Reactive Antibody Testing in the Planning and Management of Ocular Surface Stem Cell Transplantation

PURPOSE

Panel-reactive antibody (PRA) testing has been widely adopted in solid organ transplantation for risk assessment in potential allograft recipients but has not been studied in the context of ophthalmic transplantation. The purpose of this study is to evaluate outcomes in patients undergoing ocular surface stem cell transplantation (OSST) for limbal stem cell deficiency (LSCD) relative to preoperative PRA level.

METHODS

This is retrospective chart review of all eyes with documented PRA level that underwent OSST for LSCD between May 2000 and March 2019 at a single institution. Eyes with stable ocular surface but <1 year of follow-up and eyes without updated PRA before repeat OSST were excluded. Eyes were grouped by PRA <80% and ≥80%. The primary outcome was ocular surface failure, whereas the secondary outcome was clinical allograft rejection.

RESULTS

Sixty-nine surgeries met inclusion criteria, consisting of 54 living-related conjunctival limbal allografts, 5 keratolimbal allografts, and 10 combined living-related conjunctival limbal allografts/keratolimbal allografts (Cincinnati procedure). The most common etiologies for LSCD were aniridia (33%), chemical/thermal injury (28%), and contact lens associated (14%). Surface failure occurred in 5 of 12 eyes (58%) with PRA ≥80% versus 12 of 57 eyes (21%) with PRA <80% (P = 0.01). The relative risk for surface failure with PRA ≥80% was 2.8 [confidence interval (CI), 1.38-5.55]. There was no significant difference in acute rejection (P = 1).

CONCLUSIONS

Pretransplant PRA level is an important prognostic factor for ocular surface stability in eyes undergoing OSST for LSCD, with implications for donor selection, perioperative management, and systemic immunosuppression.

Evaluation of Living Kidney Donor and Recipient Candidates: The Experience of Our Center

PURPOSE

We evaluated potential kidney living donors and recipients for donation in our transplant center.

MATERIALS AND METHODS

Candidates to be kidney living donors and kidney transplant recipients (KTxR) were retrospectively evaluated. All candidates were informed and assessed by transplant coordinator and nephrologists. All data were obtained from archive records.

RESULTS

The mean ages of 194 kidney living donors and 182 KTxR were 45.7 ± 13.1 and 37.7 ± 14.6 years, respectively. Percentages of female candidates were 55.2% and 34.1% among kidney living donors and KTxR respectively. The kidney living donor candidates were the patients' mothers (27.3%), spouses (24.2%), siblings (21.6%), fathers (12.4%), and sons or daughters (6.2%) of KTxRs and others (8.2%). The numbers of donors with body mass index (BMI) > 30 kg/m² and > 35kg/m² were 56 (28.9%) and 17 (8.8%) respectively. Due to withdrawal from donation (21.2%) and renal problems (15.3%), 85/194 (43.8%) kidney living donors were excluded. Of the remaining 51/182 (28%) KTxR candidates, 26/182 (14.2%) were unsuitable because their panel-reactive antibody (PRA) > 20%. Sixty-six KTxR were performed in our center. Nine donor candidates were rejected due to obesity (BMI > 35 kg/m²).

CONCLUSION

Most of our kidney living donors were mothers, housewives, and uneducated persons. Due to high percentages of suitability among candidates of KTxRs and kidney living donors as 72% and 56% may be an advantage for living kidney donation. However, PRA positivity in the recipients drew attention as a major barrier. The high incidence of obesity among the donor candidates suggests that societies must be more sensitive about this issue.

The Pre-Transplant Drop in Panel-Reactive Antibodies Titer Evaluated Using Complement-Dependent Cytotoxicity (PRA-CDC) and the Risk of Early Acute Rejection in Sensitized Kidney Transplant Recipients

Background: The panel-reactive antibodies that use the complement-dependent cytotoxicity test (PRA-CDC) are still a standard method for monitoring the degree of immunization in kidney transplant candidates on active waiting lists in some countries, including Poland. The aim of this study was to analyze the relationship between the maximum and the last pre-transplant PRA titer on the percentage of positive cross-matches and rate of early acute rejection episodes. Material and methods: The retrospective analysis included 528 patients from two transplant centers. All patients were divided into three groups, depending on their peak and last pre-transplant PRA titers. There were 437 (82.8%) patients with peak PRA <20% (non-sensitized group, non-ST) and 91 (17.2%) patients with peak PRA >20%. Among the latter group, 38 had maintained PRA level >20% at the time of transplantation (sensitized patients, ST), whereas 53 had pre-transplant PRA ≤20% (previously sensitized patients, prev-ST). Results: The percentages of positive crossmatches were 76.9% in ST and 53.7% in prev-ST groups versus 18.4 in non-ST group (both p < 0.001). The acute rejection rates were 18.9, 17.6 and 6.8%, respectively (p < 0.001 for ST or prev-ST versus non-ST). The pre-transplant PRA titer drop did not decrease the risk of early acute rejection [OR = 1.09 (95% CI: 0.31–3.85)] in a multiple logistic regression analysis. The occurrences of primary graft non-function and delayed graft function were similar in all study groups. Conclusions: Previously immunized kidney transplant candidates even with substantial decrease in pre-transplant PRA-CDC levels are still at high immunological risk when compared with non-immunized patients, and they should receive lymphocyte-depleting induction therapy.

Predictive Factors of Acute Rejection in Low Immunologic Risk Kidney Transplant Recipients Receiving Basiliximab

INTRODUCTION

The optimal immunosuppressive induction therapy in kidney transplant recipients with low immunologic risk of acute rejection (AR) is still controversial. The use of basiliximab (BSX) has led to a significant decrease of AR with a low side effect profile.

OBJECTIVE

This study sought to evaluate predictive risk factors for AR in low immunologic risk patients subjected to immunosuppressive induction therapy with BSX.

METHODS

We reviewed all low immunologic risk patients (panel reactive antibody [PRA] level <50%, who had undergone a first deceased-donor transplant) subjected to immunosuppressive induction therapy with BSX, calcineurin inhibitor, mycophenolate mofetil, and prednisolone (n = 346). AR was defined as any rejection occurring until 12 months posttransplantation. Predictive risk factors for AR were evaluated by logistic regression and, to find the best cut-off of PRA related to a higher incidence of AR, receiver-operator characteristic (ROC) curve analysis was performed.

RESULTS

The rate of AR was 7.8%. Multivariate logistic regression analysis identified age at the time of transplantation (P = .040) and PRA level (P = .001) as independent risk factors for AR. ROC curve analysis confirmed that PRA >10% was related to an increased incidence of AR (19.2% vs 6.0%, P = .005).

CONCLUSIONS

A higher incidence of AR was observed in low immunologic risk kidney transplant patients with a PRA level >10%. These data support the use of more intensive immunosuppressive induction therapy in patients with low immunologic risk and a PRA level >10%.

Management of sensitized pediatric patients prior to renal transplantation

BACKGROUND

Data on renal allograft outcome in sensitized children are scarce. We report the clinical courses of four children who received desensitization therapy prior to renal transplantation in our institution.

METHODS

Between 2009 and 2011, four pediatric patients with stage 5 chronic kidney disease received desensitization therapy due to: (1) positive donor-specific antibodies (DSA) and/or crossmatches with potential living donors, (2) more than three positive crossmatches with deceased donors or (3) high calculated panel-reactive antibody of >80 %. Desensitization with rituximab, intravenous immunoglobulin and bortezomib was performed in all patients. Induction therapy included combinations of plasmapheresis and/or alemtuzumab or anti-thymocyte globulin. Standard post-transplant medications included tacrolimus, mycophenolate mofetil and prednisolone.

RESULTS

Post-transplant screening revealed DSA in three patients. Biopsy showed no evidence of rejection at 1 month in two patients, one of whom developed chronic active antibody-mediated rejection 4.5 years later. One patient developed borderline acute cellular rejection at 1 month, but the serum creatinine level was stable and DSA disappeared without treatment 1 month later, with stable long-term allograft function at 3 years. Estimated or measured glomerular filtration rate of the patients ranged between 30 and 75 ml/min/1.73 m(2) after 1 to 4.5 years.

CONCLUSIONS

The four sensitized patients reported here who received desensitization therapy had successful renal transplants with a low risk of immediate post-transplant rejection. Overall, long-term allograft functions and complications from immunosuppression were encouraging.

Significance of HLA Antibody Detected by PRA-Bead Method in Kidney Transplant Outcomes

BACKGROUND

The impact of specific HLA antibodies on the allograft function in the Luminex era is not clearly known. This study aimed to investigate kidney transplantation outcomes in patients with different anti-HLA antibody status as detected by Luminex PRA.

METHODS

This retrospective study included 106 deceased-donor kidney transplantation (DDKT) patients divided into 3 groups by PRA status as detected by PRA-bead: (1) PRA = 0; (2) positive PRA but with negative antibody against donor's HLA antigens; and (3) positive PRA with positive anti-HLA antibody specificity against donor's HLA antigens.

RESULTS

There were 65, 23, and 18 patients in groups 1, 2, and 3, respectively. Early allograft rejections were highest in group 3 (22.2%) (P = .02). In multivariate analysis, delayed graft function was the only factor that was associated with allograft rejection (hazard ratio, 8.9; 95% confidence interval, 1.9-39.8; P = .004). Estimated glomerular filtration rates at 1 year of the 3 groups were 54.6, 55.8, and 60.0 mL/min (P = .71). One-year allograft failure and death were not different among the 3 groups. Expanded-criteria deceased donors were associated with both allograft failure (P = .003) and patient death (P = .02).

CONCLUSIONS

Anti-HLA antibody as detected by Luminex PRA was associated with early allograft rejection but not graft or patient survival. The effect of newer treatment modalities can improve the outcomes of PRA-positive patients to be similar to nonsensitized patients at 1 year.

Loss of CD28 on Peripheral T Cells Decreases the Risk for Early Acute Rejection after Kidney Transplantation

Background

End-stage renal disease patients have a dysfunctional, prematurely aged peripheral T-cell system. Here we hypothesized that the degree of premature T-cell ageing before kidney transplantation predicts the risk for early acute allograft rejection (EAR).

Methods

222 living donor kidney transplant recipients were prospectively analyzed. EAR was defined as biopsy proven acute allograft rejection within 3 months after kidney transplantation. The differentiation status of circulating T cells, the relative telomere length and the number of CD31⁺ naive T cells were determined as T-cell ageing parameters.

Results

Of the 222 patients analyzed, 30 (14%) developed an EAR. The donor age and the historical panel reactive antibody score were significantly higher (p = 0.024 and p = 0.039 respectively) and the number of related donor kidney transplantation was significantly lower (p = 0.018) in the EAR group. EAR-patients showed lower CD4⁺CD28null T-cell numbers (p<0.01) and the same trend was observed for CD8⁺CD28null T-cell numbers (p = 0.08). No differences regarding the other ageing parameters were found. A multivariate Cox regression analysis showed that higher CD4⁺CD28null T-cell numbers was associated with a lower risk for EAR (HR: 0.65, p = 0.028). In vitro, a significant lower percentage of alloreactive T cells was observed within CD28null T cells (p<0.001).

Conclusion

Immunological ageing-related expansion of highly differentiated CD28null T cells is associated with a lower risk for EAR.

Peak panel reactive antibody, cancer, graft, and patient outcomes in kidney transplant recipients

BACKGROUND

High levels of pretransplant panel reactive antibodies (PRA) are known to be associated with detrimental effects on graft outcomes, but the association between pretransplant PRA levels and long-term patient outcomes is unclear.

METHODS

Using the Australian and New Zealand Dialysis and Transplant Registry (ANZDATA), we assessed the risk of rejection, graft failure, mortality and cancer in kidney transplant recipients with varying peak PRA levels.

RESULTS

In 7,118 kidney transplant recipients between 1997 and 2009, there were a total of 3,171 (44.6%), 3,306 (46.4%), 323 (4.5%), and 318 (4.5%) recipients with peak PRA levels of 0%, 1% to 50%, 51% to 80%, and greater than 80%, respectively. Compared to recipients with 0% peak PRA level, recipients with peak PRA levels greater than 80% were at increased risk of acute rejection (odds ratio, 1.81, 95% confidence interval [95% CI], 1.30-2.35; P < 0.001), death censored graft failure (hazard ratio [HR], 2.06; 95% CI, 1.46-2.91; P < 0.001), all-cause mortality (HR, 1.56; 95% CI, 1.15-2.11; P < 0.001) and cancer (HR, 1.94; 95% CI, 1.26-2.97; P = 0.002) in the adjusted models independent of human leukocyte antigen mismatches and initial immunosuppression.

CONCLUSION

Highly sensitized kidney transplant recipients with peak PRA greater than 80% had a greater risk of rejection, graft failure, cancer and death independent of age and time on dialysis. Strategies to reduce transplant waiting time and avoidance of sensitization in all potential transplant candidates are imperative to improve the overall graft and patient survival.

Long-term outcome on kidney retransplantation: a review of 100 cases from a single center

Renal transplantation has become an effective form of treatment for end-stage renal failure. Unfortunately, as a consequence of immunological and nonimmunological pathogenic mechanisms, chronic allograft nephropathy is responsible for the loss of a large proportion of kidney grafts after several years and return to dialysis. We have reported herein our 24 years of experience with second kidney transplantations. Of 1,302 kidney transplantations between January 1983 and June 2007 performed in our transplantation center, 100 were second transplantations. Kidney retransplantation was performed in 74 men and 26 women of overall mean age of 35.4 +/- 12.6 years. Cadaveric donor grafts were transplanted in 92 patients, whereas the remaining 8 were living-related donor kidneys. At 1, 5, and 10 years after kidney transplantation, patient survival rates were 100%, 96%, and 92%, respectively, whereas graft survival rates were 85%, 72%, and 53%, respectively. Immunosuppressive therapy included induction therapy with polyclonal anti-lymphocyte antibodies (ALG/ATG) or (starting from 1999) monoclonal anti CD 25 antibody. Our results demonstrated good outcomes for kidney retransplantations with allocation based on anti- HLA antibody identification together with induction immunosuppression.

A successful bilateral lung transplantation in a patient with high panel reactive antibody and positive cross matching

A 44-year-old pregnant female patient gave stillbirth while being treated for pneumonia. She developed acute respiratory failure, which resulted in mechanical ventilator support. Diagnostic lung biopsy revealed a cryptogenic organizing pneumonia. The patient’s condition deteriorated and a venous-venous extracorporeal membrane oxygenation was placed. She was listed for lung transplantation. Because of her worsening condition lung transplantation was performed despite positive cross matching result. She was treated with rituximab, intravenous immunoglobulin, and plasmapheresis and recovered without event. There is no sign of rejection at the time of last follow-up.

Proinflammatory events are associated with significant increases in breadth and strength of HLA-specific antibody

Identification of factors responsible for an increase in the breadth or strength of HLA-specific antibody (HSA) is critical to the continued successful management and transplantation of sensitized patients. A retrospective review of our HLA registry identified 107 patients with known HSA and sufficient information in their electronic patient record to determine the presence or absence of a proinflammatory event. The patients were stratified according to transplant status [sensitized and on the transplant waitlist (n = 65); immunosuppressed recipients of a positive crossmatch (+XM) transplant (n = 42)]. Eighty-three percent of waitlist candidates and 55% of sensitized kidney transplant recipients with a documented proinflammatory event had an associated increase in HSA. Interestingly, among patients with a culture-proven infection, 97% of the waitlist patients and 54.8% of +XM recipients had an associated rise in HSA. Overall, proinflammatory events were associated with a greater increase among waitlist patients than +XM recipients, 5.3-fold [IRR 5.25, (95% CI 4.03-6.85), p < 0.001] versus 2.5-fold [IRR 2.54, (95% CI 1.64-3.95), p < 0.001] increase in HSA. Therefore, sensitized patients known to have an infection or undergoing surgery should be monitored for expansion of HSA.

Human facial allotransplantation: a 2-year follow-up study

BACKGROUND

Progress in composite tissue allotransplantation could provide a new treatment for patients with severe facial disfigurements. We did a partial facial allotransplantation in 2006, and report here the 2 year follow-up of the patient.

METHODS

The recipient, a 30-year-old man from China, had his face severely injured by a bear in October, 2004. Allograft composite tissue transplantation was done in April, 2006, after careful systemic preparation. The surgery included anastomosis of the right mandibular artery and anterior facial vein, whole repair of total nose, upper lip, parotid gland, front wall of the maxillary sinus, part of the infraorbital wall, and zygomatic bone. Facial nerve anastomosis was done during the surgery. Quadruple immunomodulatory therapy was used, containing tacrolimus, mycophenolate mofetil, corticosteroids, and humanised IL-2 receptor monoclonal antibody. Follow-up included T lymphocyte subgroups in peripheral blood, pathological and immunohistochemical examinations, functional progress, and psychological support.

FINDINGS

Composite tissue flap survived well. There were three acute rejection episodes at 3, 5, and 17 months after transplantation, but these were controlled by adjustment of the tacrolimus dose or the application of methylprednisolone pulse therapy. Hepatic and renal functions were normal, and there was no infection. The patient developed hyperglycaemia on day 3 after transplantation, which was controlled by medication.

INTERPRETATION

Facial transplantation could be successful in the short term, but the procedure was not without complications. However, promising results could mean that this procedure might be an option for long-term restoration of severe facial disfigurement.

Detection and analysis of HLA class I and class II specific alloantibodies in the sera of dialysis recipients waiting for a renal retransplantation

The objective of this study was to evaluate the specificities of HLA class I (-A,-B) and class II (-DR,-DQ) antibodies (Ab) detected in the sera of alloimmunized patients waiting for a subsequent renal transplantation. The study group consisted of 62 dialysis patients (42 men and 20 women, mean age: 43 +/- 18 yr) on waiting list for a subsequent kidney transplant (52 for a second and 10 for a third transplant) at S. Martino Hospital Transplant Centre in Genoa/Italy, who were enrolled from 2002 to 2004 for HLA antibody screening. Complement dependent cytotoxicity (CDC) technique was used firstly to select anti-HLA class I sensitized patients; indeed sera from 50 individuals out of 62 (80.6%) were found to display persistent HLA class I PRA (panel reactive antibody) values >4% (range: 20-100). ELISA technique was subsequently adopted to analyze HLA class I Ab positive sera for the presence also of HLA class II Ab and to characterize class I and class II Ab specificities. Anti-class I immunized patients were divided in three groups according to the type of class I Ab specificities, that were classified as private, public, and multispecific. The first group included 35 patients (70% of the total number of positive patients) showing only antibodies directed against private HLA class I specificities, represented in 33 cases by those expressed by graft donors (first or second transplant). In this group anti-class I PRA% values ranged from 20% to 60%. HLA class II Ab, with an heterogeneous specificity pattern (private, public or multispecific), were present in 25 (78.1%) out of the 32 patients, whose sera were also available for this analysis. The second group comprised 12 patients (24%) who displayed antibodies directed against class I public epitopes belonging to CREGs (Cross reactive Groups) or an association of anti-private and anti-public antibodies. In this group PRA values ranged from 25% to 90%. Five patients (46.7%) were positive for HLA class II Ab, whose specificity pattern appeared also heterogeneous (private or multispecific). The third group was represented by three patients (6%) displaying multispecific antibodies with PRA values > or = 90%. No multispecific class II Ab were found in this group, where only two patients had class II Ab showing anti-private or anti-private plus public specificities. Globally, 74% of anti-class I Ab positive patients, having at least one HLA class II antigen mismatch, appeared also positive for class II Ab. These results indicate that: (i) a large proportion of patients, waiting for a kidney retransplantation, display in their sera alloantibodies specific for graft mismatched HLA class I (80.6%) and class II antigens (54.2); (ii) the immunogenic determinants, mainly involved in HLA class I and II specific Ab production, were, in a significant rate, private specificities of mismatched HLA antigens (70% for class I and 59.4% for class II), and in a lesser percentage by public (CREG) epitopes (24% for class I and 34.3% for class II). In a few patients only no HLA class I and class II Ab specificities could be determined, as they displayed multispecific antibodies (6% for class I and 6.2% for class II). These findings may have important implications to improve donor-recipient matching in dialysis recipients waiting for a subsequent renal transplantation.