Panel Of Reactive Antibodies Research Articles

Imunological aspects of kidney retransplantation.

The number of patients on the waiting list for akidney retransplant has increased. Patients who are candidates for asecond kidney transplant often have higher levels of PRA (Panel of Reactive Antibodies). The previous failed kidney transplant is one of the main factors that leads to the production of antibodies against human leukocyte antigens ‒ HLA. The consequences of sensitisation are along waiting time for repeated kidney transplantation and anegative effect on graft survival after retransplantation.The aim of our analysis was to evaluate the immunological parameters of patients undergoing renal retransplantation at the Kosice Transplant Centre, their influence on graft function, the occurrence of rejection episodes and to analyse the sensitisation status of recipients on the waiting list for renal retransplantation at the Kosice Transplant Centre.We retrospectively analysed 46 adult patients who underwent secondary renal transplantation. In the group of retransplanted patients, we found ahigher immunological risk and PRA values (p<0.001) and ahigher need for induction therapy to reduce the lymphocyte count (p<0.001). Retransplant patients with DGF were 48% more likely to experience acute rejection.In the context of the published literature, we have observed increased sensitisation in retransplanted patients, which is amajor challenge to overcome the immunological barrier in transplantation medicine (Tab. 4, Fig. 1, Ref. 24). Keywords: retransplantation, sensitisation, panel of reactive antibodies.

I Got It from My Mamma: Sensitization by Transplacental Transfer of Maternal HLA Antibodies Managed with Manual Exchange Transfusion

<h3>Introduction</h3> During pregnancy antibodies are passed from mother to fetus with many known immunologic benefits. There is no data about the implications of this on pediatric transplant immunology. We report a case of transplacental transfer of maternal Human Leukocyte Antigen (HLA) antibodies affecting cardiac transplant candidacy in an infant with cardiomyopathy. <h3>Case Report</h3> A 3-week-old Amish boy with a homozygous MYBPC3 mutation causing severe cardiomyopathy admitted for refractory heart failure symptoms was referred for heart transplant evaluation. Labs were notable for high levels of high Mean Fluorescence Intensity (MFI) HLA antibodies (Panel of Reactive Antibodies (PRA) Class I: 74%, Class II: 80%) with no known sensitizing events. Maternal history was remarkable for multiple miscarriages raising the question that his HLA antibodies could be a result of maternal HLA sensitization with transplacental antibody transfer versus active antibody production by the child. Subsequent antibody testing of his mother's blood and breast milk revealed nearly identical HLA antibody profiles to that of the patient. Given the patient's prohibitively small size for antibody removal by plasmapheresis, we elected to perform double volume whole blood exchange transfusions with serial monitoring of his HLA antibodies. Considering his severe ventricular dysfunction, exchange transfusions were performed manually via the push pull method over 6 hours. He ultimately underwent 6 exchange transfusions over the course of 7 weeks. Serial antibody testing revealed a progressive decline in all his HLA antibody levels to <3,000 MFI with only mild rebound after each transfusion consistent with tissue redistribution rather than active antibody production. He was successfully transplanted with a negative PRA (Class I: 0%, Class II: 0%) without post-transplant complications. <h3>Summary</h3> We believe this is the first report demonstrating transplacental acquisition of maternal HLA antibodies in an infant successfully removed via serial whole blood exchange transfusions enabling successful cardiac transplantation.

Treatment of Antibody-Mediated Rejection After Kidney Transplantation: Immunological Effects, Clinical Response, and Histological Findings.

BackgroundAntibody-mediated rejection (AMR) presents with diverse clinical manifestations and can have a potential negative impact on graft function and survival. If not treated successfully, AMR can lead to 20–30% graft loss after 1 year. Little is known about the efficacy of AMR treatment, and the most appropriate therapeutic strategy has not yet been determined. This study evaluated the effects of AMR treatment with plasmapheresis (PP) and intravenous immunoglobulin (IVIG) on renal function, intensity of anti-HLA antibodies, and graft biopsy morphology.Material/MethodsThis single-center retrospective cohort study included renal transplant recipients with biopsy-proven AMR who were treated with PP and/or IVIG. Clinical findings, mean fluorescence intensity of donor-specific anti-HLA antibodies (DSA), and graft histology findings, classified according to Banff score at the time of AMR and 6 and 12 months later, were evaluated.ResultsOf the 42 patients who met the inclusion criteria, 38 (90.5%) received IVIG and 26 (61.9%) underwent PP. At AMR diagnosis, 36 (85.7%) patients had proteinuria, with their estimated glomerular filtration rate remaining stable during follow-up. During the first year, 8 (19.0%) patients experienced graft failure, but none died with a functioning graft. Reductions in the class I panel of reactive antibodies were observed 6 and 12 months after AMR treatment, with significant reductions in DSA-A and -B fluorescence intensity, but no changes in DSA-DQ. Graft biopsy showed reductions in inflammation and C4d scores, without improvements in microvascular inflammation.ConclusionsAMR treatment reduced biopsy-associated and serological markers of AMR, but did not affect DSA-DQ.

Elevated Cytotoxic T Cells is Associated with Allosensitization of Patients Supported by a Continuous-Flow Left Ventricular Assist Device

Introduction Use of CFLVADs as a BTT continues to increase. The mechanisms of host immune system activation following implantation leading to allosensitization complicating transplantation outcomes are not well understood. Hypothesis We hypothesize that pre-implant cell profiles may predict post-implant allosensitization. Methods Plasma and PBMC samples were collected before implant (D0), 48 hours post-implant (D2) and 8 days post-implant (D8) in 12 CFLVAD patients. HLA class I and II antibody profiles were obtained pre and post-implant. Calculated panel of reactive antibodies (cPRA) were calculated using the OPTN calculator. Plasma aliquots were randomized and performed in duplicate. Lymphocyte phenotypes were analyzed by multiparameter flow cytometry across 3 randomized panels. Results Mean age of patients was 53.6±15.3 years, 50% were female and 33% had ischemic cardiomyopathy. Following implant there was a significant increase of Treg cells (CD4+Foxp3+CD25+ 1.07±0.39 p=0.005), T effector cells (CD4+Foxp3−CD25+ 13.2±2.83 p=0.0007) and B cells (CD3−CD19+ 7.17±2.93 p=0.032). This was accompanied with a decrease in CD3+ T cells (-10.1±3.69 p=0.019), cytotoxic T cells (CD3+CD8+ -3.28±1.12 p=0.014), and NK cells (CD3−CD19−CD56+ -3.86±1.72 p=0.047). Three patients had an increase in cPRA post-implant. All 3 patients had significantly increased cytotoxic T cells compared to patients with no increase (D0 18.4±2.46 vs 7.69±5.79 p=0.013); (D2 15.8±3.12 vs 6.74±3.61 p=0.012); (D8 13.9±3.64 vs 4.83±2.99 p=0.002) ( Figure 1 ). A significant increase in the plasma cytokines IL-6 (D0 79.7 D2 1320 D8 240 p Conclusion We show an impaired cellular immunity characterized by an acute rise in Treg, T-effector cells as well as B cells while the tissue aggressive response decreased. IL-6, IL-8 and G-CSF increased significantly post-implant in sensitized patients. Surprisingly, high CD8+ T cells pre-implant were associated with an increased cPRA in our cohort. CD8+ T cells in these patients decreased after implant but remained 2-fold higher than those patients with no increase in cPRA. Higher levels of cytotoxic T cells pre-implant may predict post CFLVAD implant allosensitization. Characterizing pre-implant cell profiles may be useful in identifying appropriate CFLVAD recipients.

Prediction of delayed graft function after renal transplantation

Delayed graft function (DGF), defined as the need for dialysis during the first week after renal transplantation, is an important adverse clinical outcome. A previous model relied on 16 variables to quantify the risk of DGF, thereby undermining its clinical usefulness. We explored the possibility of developing a simpler, equally accurate and more user-friendly paradigm for renal transplant recipients from deceased donors. Logistic regression analyses addressed the occurrence of DGF in 532 renal transplant recipients from deceased donors. Predictors consisted of recipient age, gender, race, weight, number of HLA-A, HLA-B and HLA-DR mismatches, maximum and last titre of panel reactive antibodies, donor age and cold ischemia time. Accuracy was quantified with the area under the curve. Two hundred bootstrap resamples were used for internal validation. Delayed graft function occurred in 103 patients (19.4%). Recipient weight (p < 0.001), panel of reactive antibodies (p < 0.001), donor age (p < 0.001), cold ischemia time (p = 0.005) and HLA-DR mismatches (p = 0.05) represented independent predictors. The multivariable nomogram relying on 6 predictors was 74.3% accurate in predicting the probability of DGF. Our simple and user-friendly model requires 6 variables and is at least equally accurate (74%) to the previous nomogram (71%). We demonstrate that DGF can be accurately predicted in different populations with this new model.

Incidence and Factors Associated With Delayed Graft Function in Renal Transplantation at Carlos Van Buren Hospital, January 2000 to June 2008

Delayed graft function (DGF) is defined as the need for dialysis within the first week after renal transplantation, and slow graft function as persistence of serum creatinine concentration of at least 3 mg/dL on day 5 after the procedure. In the present study, we analyzed the incidence and risk factors for DGF at our center. This retrospective study included 106 patients who underwent renal transplantation between January 2000 and June 2008. Of these, 11 patients were excluded. Two of the remaining 95 patients received organs from living donors, and 93 received cadaver organs. Variables analyzed included donor age, cause of death, cause of chronic renal failure, recipient age, method and time of long-term renal replacement therapy, residual diuresis, panel of reactive antibodies (PRA), HLA mismatch, sex compatibility, cold and warm ischemia times, biopsy-confirmed episodes of acute rejection, urine output in the operating room and in the first 24 hours after the procedure, and intraoperative induction therapy. Data were analyzed using the chi(2) and Fisher exact tests and analysis of variance, and are given as mean (SD) and frequency. Variables associated with DGF at univariate analysis (P < .05) were divided between risk factors and predictors of DGF for inclusion in logistic regression models. The incidence of DGF was 32.6%; slow graft function, 16.8%; and immediate graft function, 50.5%. Cold ischemia time longer than 20 hours (P = .02) and donor age (P = .008) were directly associated with DGF. Twenty-four-hour urine output was a strong predictor of DGF. Patients with DGF demonstrated a 25% incidence of an episode of acute rejection before discharge from the hospital. No difference in DGF was observed for use of intraoperative induction therapy.

Alemtuzumab induction and triple maintenance immunotherapy in kidney transplantation from donors after cardiac death

We have used alemtuzumab in combination with triple maintenance immunosuppression in renal transplantation from donors after cardiac death between 2002 and 2006. We compared outcomes of induction therapy with alemtuzumab with interleukin-2 (IL-2) receptor antagonists (RA) and anti-lymphocyte antibodies. We used a retrospective sequential study design to examine 170 recipients of kidneys from donor after cardiac death (DCD) for survival, graft survival, time to first rejection, glomerular filtration and complications. Patients were stratified into high-risk and low-risk groups based on the following criteria: panel of reactive antibodies >20%, retransplants, Afro-American race. Induction with alemtuzumab was compared with anti-thymocyte globulin (ATG) in the high-risk and with IL-2RA in the low-risk group. Patients received triple immunosuppression with steroids, mycophenolate mofetil and calcineurin inhibitors. Patient survival, graft survival, rejection rate and glomerular filtration rate did not significantly differ between patients treated with alemtuzumab versus IL-2RAs or ATG. There was a trend towards reduced graft- and patient survival in the alemtuzumab group. There was an increased incidence of cytomegalovirus (CMV) infections in the alemtuzumab-induced group and a trend towards increased BK virus and bacterial infections. Induction of DCD kidney transplants with alemtuzumab compared to IL-2RA and ATG has no significant impact on acute rejection. It appears however that CMV infections are increased in patients induced with alemtuzumab. We therefore conclude that induction with alemtuzumab does not confer any advantage over traditional induction agents.

A Comparative Analysis Between Survivors and Nonsurvivors with Antibody Mediated Cardiac Allograft Rejection

Antibody mediated rejection (AMR) is an important cause of graft loss in the post heart transplant period. The following study was conducted to determine differences between survivors and nonsurvivors who developed post heart transplant AMR. We retrospectively reviewed the charts of patients who received a heart transplant between January 1993 and December 2002. Patients with biopsy proven AMR were identified. This group was divided into survivors and nonsurvivors. Groups were compared with regards to demographics, T-cell flow panel of reactive antibodies (PRA), flow cross-matches (anti-donor HLA Class I and II), and short- and long-term outcomes. Results of endomyocardial biopsies were collected to allow calculation of sensitivity, specificity, negative- and positive predictive values as well as accuracy of immunoglobulins and complement split products in association to death. A total of 65 patients (8.9%) were diagnosed with AMR. Mean age was 48 y (range: 8-68 y) and 53.8% were males. Episodes of hemodynamic instability associated with AMR were observed in 37% of patients. Only two deaths were directly attributed to acute AMR. Nearly 20% of AMR patients developed transplant coronary artery disease. Univariate analysis identified T-PRA (P < 0.001), mean T-cell molecules of equivalent soluble fluorochrome (MESF) (P < 0.001) and mean B-cell MESF (P < 0.001) as possible factors associated with death. Neither demographics of complement split products were associated to late death. When studying patients with AMR, pretransplant T-PRA, T-cell, and B-cell MESF may identify individuals at risk of late death.

P147: A comparative analysis between survivors and non-survivors with cardiac allograft antibody-mediated rejection

Background: Antibody mediated rejection (AMR) is an important cause of graft loss in the post heart transplant period. The following study was conducted to determine differences between survivors and non-survivors who developed post heart transplant AMR. Methods: We retrospectively reviewed the charts of patients who received a heart transplant between Jan 1993 and Dec 2002. Patients with biopsy proven AMR were identified. This group was divided into survivors and non-survivors. Groups were compared with regards to demographics, T-cell flow panel of reactive antibodies (PRA), flow cross-matches (anti-donor HLA Class I and II), and short- and long-term outcomes.