Acute T Cell-mediated Rejection Research Articles

Very Low Frequency of Pathological Findings in One-year Protocol Biopsies of Uneventful Standard Risk Kidney Transplant Recipients: Results From the Nordic Protocol Biopsy Study.

The clinical significance of kidney transplant protocol biopsies has been debated. We studied the frequency of borderline changes and T cell-mediated rejection (TCMR) in 1-y protocol biopsies in standard risk kidney transplant recipients. Consecutive non-HLA-sensitized recipients of kidney transplants between 2006 and 2017, who underwent a protocol biopsy at 1 y in 2 national transplant centers were studied retrospectively (N = 1546). Donor-specific HLA antibodies (DSAs), graft function (plasma creatinine), and proteinuria were measured at the time of 1-y protocol biopsy. The occurrence of subclinical acute TCMR (i2t2v0 or higher) or borderline changes suspicious of TCMR (i1t1v0 or higher) in the protocol biopsy was studied, together with frequency of findings causing changes in the composite score iBox. Subclinical acute TCMR was detected in 30 of 1546 (1.9%) of the protocol biopsies, and borderline or TCMR in 179 of 1546 (12%). Among patients with no history of acute rejection, and no proteinuria or DSA, TCMR was detected in only 1 of 974 (0.1%) and borderline or TCMR in only 48 of 974 (4.9%) patients at 1 y. In the absence of proteinuria (<30 mg/g, or equivalent as measured with a negative dipstick proteinuria) or DSA, or history of acute rejection, only 50 of 974 (5.1%) biopsies showed any lesions significant for the iBox score. The likelihood of pathological findings in 1-y protocol biopsies in non-HLA-sensitized patients without previous immunological events is low. Clinical usefulness of protocol biopsies seems limited in these patients.

Borderline rejection: To treat or not to treat?

IntroductionIt is unclear whether kidney transplant recipients with a biopsy diagnosis as a “borderline” acute T-cell mediated rejection (TCMR) requires the treatment with intravenous (iv) steroids pulse plus/minus intensification of the maintenance therapy (TRT) in comparison with the simple clinical follow-up (F-UP). MethodsWe retrospectively followed a consecutive series of kidney transplant recipients diagnosed with a borderline acute TCMR at biopsy by surveillance or clinical indication for 12 months and compared TRT and F-UP groups. We evaluated trends in renal function by measuring estimated glomerular filtration rate (eGFR) using multiple regression models. Repeated eGFR measures (REML) were adjusted for potential confounding factors for 12 months. The difference in 12-month eGFR values were observed in the TRT vs F-UP groups, type of biopsy, as well as the surveillance vs. clinical outcomes. ResultsOut of 59 included patients, 37% of them were in the TRT group and remaining 63% in the F-UP group. As expected, the TRT group had, at the time of biopsy, lower eGFR value of 39.0 ml/min/m2 [16.5] in comparison to 49.6 [19.6] ml/min/m2 in the F-UP group (P = 0.043), Similarly, the TRT group required more frequent clinical biopsies vs. F-UP group (68% vs. 32%; P = 0.014). However, the TRT group recovered kidney function reaching the eGFR values of the F-UP group at 12 months; the increase being significant only in patients who received indication biopsies (P < 0.001). The estimated adjusted TRT effect on 12-month eGFR change after indication biopsy was improved by +15.8 ml/min/1.73m2 (95%CI: +0.1 to +31.4 ml/min/1.73 m2; P = 0.048 by three-way interaction term) compared to the F-UP group. ConclusionOur preliminary study supports the indication for the treatment of acute borderline TCMR only in cases with biopsies performed by clinical indication.

Screening of novel biomarkers for acute kidney transplant rejection using DIA-MS based proteomics.

Kidney transplantation is the preferred treatment for patients with end-stage renal disease. However, acute rejection poses a threat to the graft long-term survival. The aim of this study was to identify novel biomarkers to detect acute kidney transplant rejection. The serum proteomic profiling of kidney transplant patients with T cell-mediated acute rejection (TCMR) and stable allograft function (STA) was analyzed using data-independent acquisition mass spectrometry (DIA-MS). The differentially expressed proteins (DEPs) of interest were further verified by enzyme-linked immunosorbent assay (ELISA). A total of 131 DEPs were identified between STA and TCMR patients, 114 DEPs were identified between mild and severe TCMR patients. The verification results showed that remarkable higher concentrations of serum amyloid A protein 1 (SAA1) and insulin like growth factor binding protein 2 (IGFBP2), and lower fetuin-A (AHSG) concentration were found in TCMR patients when compared with STA patients. We also found higher SAA1 concentration in severe TCMR group when compared with mild TCMR group. The receiver operating characteristics (ROC) analysis further confirmed that combination of SAA1, AHSG, and IGFBP2 had excellent performance in the acute rejection diagnosis. Our data demonstrated that serum SAA1, AHSG, and IGFBP2 could be effective biomarkers for diagnosing acute rejection after kidney transplantation. DIA-MS has great potential in biomarker screening of kidney transplantation.

IL-34 attenuates acute T cell-mediated rejection following renal transplantation by upregulating M2 macrophages polarization

ObjectiveTo investigate the role of Interleukin-34 (IL-34) in acute T cell-mediated rejection (TCMR) following renal transplantation. MethodsThe mice acute TCMR model of renal transplantation was established and identified by hematoxylin and eosin (HE) and immunohistochemistry (IHC) staining. Then, IHC staining of IL-34 was also performed to determine the expression of IL-34 in allografts. Recipients were infected with IL-34 overexpression adeno-associated virus, infection efficiency of which was estimated by enzyme linked immunosorbent assay (ELISA), Western blot, and immunofluorescence. HE and IHC staining were used to estimate the grades of TCMR. Flow cytometry was performed on lymphocytes in spleens of recipients including regulatory T cells (Tregs) and M2 macrophages. The expression of cytokines in vivo was analyzed by Mouse Cytokine Grp I Panel. Finally, Tregs and M2 macrophages were cultured in vitro and treated with IL-34 to observe the effects of IL-34 on the differentiation of the cells. ResultsThe mouse TCMR model was successfully established by HE, periodic acid shiff (PAS), CD4 and CD8 IHC staining. The expression of IL-34 was significantly decreased in allografts with TCMR. BALB/c mice were successfully infected with IL-34 overexpression adeno-associated virus. Subsequently, the grade of rejection in mice TCMR model was evaluated by HE and IHC staining according to Banff criteria. It is suggested that the grade of TCMR in IL-34 overexpressed mice was significantly decreased. IHC staining and Flow cytometry showed that the proportion of Tregs and M2 macrophages in the spleens and allografts were significantly increased in IL-34 overexpressed mice. Serum levels of interferon-gamma (IFN-γ), IL-17 and tumor necrosis factor-alpha (TNF-α) were downregulated in IL-34 overexpressed mice. Moreover, IL-34 could promote macrophage M2 polarization, while failed to promote differentiation of naïve T cells into Tregs in vitro. ConclusionOverexpression of IL-34 may attenuate the progression of TCMR episodes in allografts by increasing the polarization of M2 macrophages in the spleens and allografts, which may become a potential therapeutic strategy for TCMR.

Histopathological diagnoses revealed by indication-based renal allograft biopsies: a retrospective analysis

Objectives: Although there have been several advances in post-solid organ transplantation immunosuppression medications over the last two decades, the long-term survival of renal allografts did not significantly improve. Renal allograft biopsy is a helpful tool for determining the cause of graft dysfunction and adjusting patient management. Methods: Patients who received kidney transplantation and underwent allograft biopsy in Istinye University Hospital between January 2017 and January 2023 constituted the target population of this study. Demographic parameters, clinical data and biopsy indications, and histopathological assessment results of the patients were retrospectively analyzed. Results: Overall, 74 patients were included. The histopathology results included acute T-Cell mediated rejection (TCMR) (n = 15, 20%), tubular atrophy/chronic allograft nephropathy (IFTA) (n = 11, 15%), calcineurin inhibitor (CNI) toxicity (n = 2, 3%), chronic antibody-mediated rejection (ABMR) (n = 2, 3%), borderline pathology (n = 10, 13.5%), normal histology (n = 5, 6.5%), transplant glomerulopathy (TG) (n = 5, 6.5%), acute ABMR (n = 4, 5%), acute tubular necrosis (n = 7, 9%), polyomavirus nephropathy (n = 3, 4%) and non-specific changes (n = 10, 13.5%). The C4d was positive in 12% (n = 9) of the graft biopsies. In 73% (n = 54) of cases, the treatment strategy was changed based on biopsy results. Among all patients, 19 (25.6%) lost their grafts during follow-up. Conclusions: According to the histopathological analysis results, acute TCMR, IFTA, and borderline pathology were the most common causes of renal graft dysfunction. Renal allograft biopsy led to a remarkable change in treatment strategies in a significant number of cases.

Long-Term Results in Recipients of Late Conversion to a Calcineurin Inhibitor-Free Regimen with Everolimus After Kidney Transplantation

Conversion to a calcineurin inhibitor (CNI)-free regimen in cases of CNI nephrotoxicity (CNIT) is a strategy to improve the long-term outcomes of kidney transplantation. However, the long-term results of late conversion to a CNI-free regimen using everolimus (EVR) remain uncertain. Nine kidney transplant recipients with biopsy-confirmed CNIT were enrolled. The median time of CNIT diagnosis was 9.0 years. All recipients underwent a conversion from CNI to EVR. We evaluated the clinical outcomes, development of donor-specific antibody (DSA), the incidence of rejection, alternativearteriolar hyalinosis (aah) scores, renal function changes, and T cell responses by mixed lymphocyte reaction (MLR) assay after conversion. The median follow-up after conversion was 5.4 years. Currently, 7 of 9 recipients have received a CNI-free regimen for 1.6 to 9.5 years. In the other 2 recipients, one experienced graft loss due to CNIT 3.8 years after conversion, and the other had to resume CNI due to acute T cell-mediated rejection (ATMR) a year after conversion. None of the recipients developed DSA. No rejection was observed in the kidney allograft histology except for the ATMR case. Moreover, improvement in aah scores was noted in one patient. Furthermore, serum creatinine levels were stable in recipients without proteinuria before the EVR add-on. In the MLR analysis, low responses against donors were observed in stable patients. Late conversion to an EVR-based regimen without CNI may be a promising therapeutic strategy against CNIT, particularly for recipients without proteinuria before the EVR add-on.

Banff 2016 Global Assessment and Quantitative Scoring for T Cell-Mediated Liver Transplant Rejection are Interchangeable.

Histopathological assessment of liver biopsies is the current "gold standard" for diagnosing graft dysfunction after liver transplantation (LT), as graft dysfunction can have nonspecific clinical presentations and inconsistent patterns of liver biochemical dysfunction. Most commonly, post-LT, graft dysfunction within the first year, is due to acute T-cell mediated rejection (TCMR) which is characterised histologically by the degree of portal inflammation (PI), bile duct damage (BDD), and venous endothelial inflammation (VEI). This study aimed to establish the relationship between global assessment, which is the global grading of rejection using a "gestalt" approach, and the rejection activity index (RAI) of each component of TCMR as described in revised Banff 2016 guidelines. Liver biopsies (n = 90) taken from patients who underwent LT in 2015 and 2016 at the Australian National Liver Transplant Unit were identified from the electronic medical records. All biopsy slides were microscopically graded by at least two assessors independently using the revised 2016 Banff criteria. Data were analysed using IBM SPSS v21. A Fisher-Freeman-Halton test was performed to assess the correlation between the global assessment and the RAI scores for each TCMR biopsy. Within the cohort, 60 (37%, n = 164) patients underwent at least 1 biopsy within 12 months after LT. The most common biopsy outcome (total n = 90) was acute TCMR (64, 71.1%). Global assessment of TCMR slides strongly positively correlated with PI (p value <0.001), BDD (p value <0.001), VEI (p value <0.001), and total RAI (p value <0.001). Liver biochemistry of patients with TCMR significantly improved within 4 to 6 weeks post-biopsy compared to the day of the biopsy. In acute TCMR, global assessment and total RAI are strongly correlated and can be used interchangeably to describe the severity of TCMR.

Diagnosing Acute Cellular Rejection after Paediatric Liver Transplantation-Is There Room for Interleukin Profiles?

The current gold standard to diagnose T-cell-mediated acute rejection (TCMR) requires liver histology. Using data from the ChilSFree study on immune response after paediatric liver transplantation (pLT), we aimed to assess whether soluble cytokines can serve as an alternative diagnostic tool in children suspected to have TCMR. A total of n = 53 blood samples obtained on the day of or up to 3 days before liver biopsy performed for suspected TCMR at median 18 days (range 7-427) after pLT in n = 50 children (38% female, age at pLT 1.8 (0.5-17.5) years) were analysed for circulating cytokine levels using Luminex-based Multiplex technology. Diagnostic accuracy of cytokine concentrations was assessed using a multivariable model based on elastic net regression and gradient boosting machine analysis. TCMR was present in 68% of biopsies. There was strong evidence that patients with TCMR had increased levels of soluble CXCL8, CXCL9, CXCL10, IL-16, IL-18, HGF, CCL4, MIF, SCGF-β, and HGF before biopsy. There was some evidence for increased levels of sCD25, ICAM-1, IL-6, IL-3, and CCL11. Diagnostic value of both single cytokine levels and a combination of cytokines and clinical markers was poor, with AUROCs not exceeding 0.7. Patients with TCMR showed raised levels of cytokines and chemokines reflective of T-cell activation and chemotaxis. Despite giving insight into the mechanisms of TCMR, the diagnostic value of soluble cytokines for the confirmation of TCMR in a clinical scenario of suspected TCMR is poor.

The Histological Spectrum and Clinical Significance of T Cell-mediated Rejection of Kidney Allografts.

T cell-mediated rejection (TCMR) remains a significant cause of long-term kidney allograft loss, either indirectly through induction of donor-specific anti-HLA alloantibodies or directly through chronic active TCMR. Whether found by indication or protocol biopsy, Banff defined acute TCMR should be treated with antirejection therapy and maximized maintenance immunosuppression. Neither isolated interstitial inflammation in the absence of tubulitis nor isolated tubulitis in the absence of interstitial inflammation results in adverse outcomes, and neither requires antirejection treatment. RNA gene expression analysis of biopsy material may supplement conventional histology, especially in ambiguous cases. Lesser degrees of tubular and interstitial inflammation (Banff borderline) may portend adverse outcomes and should be treated when found on an indication biopsy. Borderline lesions on protocol biopsies may resolve spontaneously but require close follow-up if untreated. Following antirejection therapy of acute TCMR, surveillance protocol biopsies should be considered. Minimally invasive blood-borne assays (donor-derived cell-free DNA and gene expression profiling) are being increasingly studied as a means of following stable patients in lieu of biopsy. The clinical benefit and cost-effectiveness require confirmation in randomized controlled trials. Treatment of acute TCMR is not standardized but involves bolus corticosteroids with lymphocyte depleting antibodies for severe, refractory, or relapsing cases. Arteritis may be found with acute TCMR, active antibody-mediated rejection, or mixed rejections and should be treated accordingly. The optimal treatment ofchronic active TCMR is uncertain. Randomized controlled trials are necessary to optimally define therapy.

P8.054: Out of the Box. Immunosuppressive Therapy With Four Drugs As Rescue Therapy in Kidney Transplant Recipients With Chronic Allograft Rejection

Introduction: Persistent or repeated episodes of acute rejection (AR) may lead to chronic allograft damage. Antibody-mediated rejection (AMR); T-cell mediated rejection (TCMR) and mixed variants (MR) of chronic kidney allograft rejection (CR) are nowadays considered as the main causes of graft loss (GL). This encompasses from endothelial damage up to fibrosis challenging immunosuppressive therapy (IT) management. IT reinforcement with a four-drug scheme (4D) including m-TOR inhibitors, anticalcineurinics, mycophenolate and steroids, could be a good strategy in this scenario, nevertheless there is no consensus about it. We present our experience with 4D in kidney transplant recipients (KT) That presented with CR or recurrent episodes of AR. Objectives: To evaluate kidney graft function (KGF), incidence of rejection and safety of a 4D in KT with CR or recurrent episodes of AR. Methods: KT on treatment with 4D from 2008 to 2021 were included. KGF was evaluated by estimated glomerular filtration rate with CKD-EPI (eGFR) and urinary protein/creatinine ratio (PCR) at 3, 6 and 12 months. Kidney biopsies and panel reactive antibodies (PRA) by Luminex were performed before and after introduction of 4D. BK virus (BKV) incidence, infectious (IE) and neoplastic (NE) events were recorded during the follow up. Results: 16 KT (median age 45 ± 11 years) were treated with 4D during 52.8 (17-106) months. 43.8% of them were women, 50% were deceased KT. The median post transplant time was 108 (60-129) months. Reasons for 4D introduction were CR in 87.4% of the cases (MR 50%; TCMR 31.3%; AMR 6.3%) and in the remaining 12, 6%, recurrent or persistent acute TCMR. Median eGFR was 42 (27-66); 44 (31-62); 48 (33-60) and 48 (32-65) ml/min prior to IT change, at 3, 6 and 12 months respectively. At baseline, mean PCR was 179 (147-664) mg/g without significant changes during follow up. Biopsy proven AR was found in 37% of KT under 4D. No NE were registered. 43% of the patients presented a non major IE, and only one patient was BKV positive during follow up with 4D. There was one GL, one loss of follow up and one death due to sepsis with functioning graft. Conclusions: KT patients with CR or recurrent episodes of AR changed to 4D IT stabilized their renal function and proteinuria. The incidence of new biopsy proven AR was 37%, and no new DSA were found or serious adverse events reported during follow-up. 4D could be a good option to halt the progression of renal damage due to rejection in KT.

Association of Predicted HLA T-Cell Epitope Targets and T-Cell–Mediated Rejection After Kidney Transplantation

The relationship between human leukocyte antigen (HLA) molecular mismatches and T-cell-mediated rejection (TCMR) is unknown. We investigated the associations between the different donor HLA-derived T-cell targets and the occurrence of TCMR and borderline histologic changes suggestive of TCMR after kidney transplantation. Retrospective cohort study. All kidney transplant recipients at a single center between 2004 and 2013 with available biopsy data and a DNA sample for high-resolution HLA donor/recipient typing (N = 893). Scores calculated by the HLA matching algorithm PIRCHE-II and HLA eplet mismatches. TCMR, borderline changes suggestive of TCMR, and allograft failure. Multivariable cause-specific hazards models were fit to characterize the association between HLA epitopes targets and study outcomes. We found 277 patients developed TCMR, and 134 developed only borderline changes suggestive of TCMR on at least 1 biopsy. In multivariable analyses, only the PIRCHE-II scores for HLA-DRB1 and HLA-DQB1 were independently associated with the occurrence of TCMR and with allograft failure; this was not the case for HLA class I molecules. If restricted to rejection episodes within the first 3 months after transplantation, only the T-cell epitope targets originating from the donor's HLA-DRB1 and HLA-DQB1, but not class I molecules, were associated with the early acute TCMR. Also, the median PIRCHE-II score for HLA class II was statistically different between the patients with TCMR compared to the patients without TCMR (129 [IQR, 60-240] vs 201 [IQR, 96-298], respectively; P< 0.0001). These differences were not observed for class I PIRCHE-II scores. Observational clinical data and residual confounding. In the absence of HLA-DSA, HLA class II but not class I mismatches are associated with early episodes of acute TCMR and allograft failure. This suggests that current immunosuppressive therapies are largely able to abort the most deleterious HLA class I-directed alloimmune processes; however, alloresponses against HLA-DRB1 and HLA-DQB1 molecular mismatches remain insufficiently suppressed. Genetic differences in the human leukocyte antigen (HLA) complex between kidney transplant donors and recipients play a central role in T-cell-mediated rejection (TCMR), which can lead to failure of the transplanted kidney. Evaluating this genetic disparity (mismatch) in the HLA complex at the molecular (epitope) level could contribute to better prediction of the immune response to the donor organ posttransplantation. We investigated the associations of the different donor HLA-derived T-cell epitope targets and scores obtained from virtual crossmatch algorithms with the occurrence of TCMR, borderline TCMR, and graft failure after kidney transplantation after taking into account the influence of donor-specific anti-HLA antibodies. This study illustrates the greater importance of the molecular mismatches in class II molecules compared to class I HLA molecules.

Immune Subsets From Ficoll Density Gradient Separation in Kidney Transplant Recipients.

Immune Subsets From Ficoll Density Gradient Separation in Kidney Transplant Recipients.

Noninvasive Diagnosis of Acute Rejection in Renal Transplant Patients Using Mass Spectrometric Analysis of Urine Samples: A Multicenter Diagnostic Phase III Trial.

Background.Timely recognition and treatment of acute kidney graft rejection is important to prevent premature graft failure. A predefined urinary marker set for acute T cell–mediated rejection (TCMR) containing 14 peptides was tested for this purpose in a multicenter in-place validation study.Methods.Three hundred twenty-nine prospectively collected and 306 archived urine samples from 11 transplant centers in Germany, France, and Belgium were examined. Samples were taken immediately before a biopsy, performed for graft dysfunction within the first transplant year. Primary outcomes were sensitivity and specificity of the marker set for the diagnosis of biopsy-proven acute TCMR, with prespecified thresholds of 83% for sensitivity and 70% for specificity.Results.Eighty-two patients (13%) had acute TCMR grade I–III. In relation to the biopsy diagnosis of TCMR, the sensitivity of the urine test was 0.66 (95% confidence interval, 0.56-0.76) and the specificity 0.47 (95% confidence interval, 0.43-0.51), with an area under the curve (AUC) of 0.60. The different TCMR grades I–III were not reflected by the marker set, and borderline TCMR was not specifically detected. Secondary independent masked assessment of biopsies consented by 2 pathologists revealed an interobserver kappa value of 0.49 for diagnosing TCMR, compared with the local center’s diagnosis. Using this consensus diagnosis, the AUC of the urine test was 0.63 (sensitivity 0.73, specificity 0.45). Post hoc optimization of the marker set improved the diagnostic performance in the study cohort (AUC 0.67) and in an independent patient cohort (AUC 0.69).Conclusions.This study illustrates the difficulty of proteomics-based diagnosis of TCMR and highlights the need for rigorous independent in-place validation and optimization of diagnostic biomarkers.

How Should Acute T-cell Mediated Rejection of Kidney Transplants Be Treated: Importance of Follow-up Biopsy.

Background.Limited published data exist to guide patient monitoring after the treatment of T-cell mediated rejection (TCMR) of kidney allografts.Methods.We reviewed the kidney function and histological outcomes after treatment of 163 first episodes of biopsy-proven TCMR between January 1‚ 2015‚ and July 31‚ 2020.Results.Of the 146 patients treated with steroid pulse alone, complete histological response was seen in 83% of patients with borderline rejection, 82.5% with grade 1A, 67% with grade 1B, and 50% with grade IIA. Of the 17 patients treated with steroids plus antithymocyte globulin, the complete histological response rate was 100% with grade 1A, 75% with grade 1B, 100% with grade IIA, and 57% with grade IIB. Among the patients with complete response as assessed by kidney function, 14% only had a partial or no response histologically. Among patients with no kidney function response, 68% had a complete response histologically.Conclusion.We thus find that responses based on kidney function alone do not correlate well with histological responses. If further treatment had been based solely on changes in estimated glomerular filtration rate, a significant number of patients would have been subsequently undertreated or overtreated. These results support the use of protocol follow-up biopsies after the treatment of TCMR.

Low Levels of Hepatocyte-Specific Methylation in Cell-Free DNA Are a Strong Negative Predictor for Acute T Cell-Mediated Rejection Requiring Treatment Following Liver Transplantation.

Graft-derived cell-free DNA (gdcfDNA) quantification is a promising, minimally invasive tool for detecting acute T cell-mediated rejection (ATCMR) following liver transplantation (LT). We investigated the utility of measuring hepatocyte-specific methylation in cfDNA (HS-cfDNA) to quantify gdcfDNA, examining its accuracy in detecting ATCMR in a prospective, cross-sectional study. Blood was collected from LT recipients immediately prior to graft biopsy for suspected rejection. HS-cfDNA was quantified using droplet-digital polymerase chain reaction. Prebiopsy liver function tests (LFTs) and HS-cfDNA levels were correlated with biopsy results and the primary outcome of treated biopsy-proven acute rejection (tBPAR). A total of 51 patients were recruited; 37 had evidence of rejection on biopsy and 20 required treatment. As much as 11 patients needed inpatient treatment for rejection. HS-cfDNA significantly outperformed LFTs in identifying patients with tBPAR, particularly those needing inpatient treatment (area under the curve, 73.0%; 95% confidence interval, 55.4%-90.6%; P = 0.01). At a threshold of <33.5% of the total cfDNA fraction, HS-cfDNA had a specificity of 97%, correctly excluding tBPAR in 30/31 patients. Quantifying graft-specific methylation in cfDNA has a major advantage over previous gdcfDNA techniques: it does not require genotyping/sequencing, lending it greater feasibility for translation into transplantation care. Low levels of HS-cfDNA were a strong negative predictor for tBPAR (negative predictive value, 86%) and may have a future role in triaging patients prior to invasive graft biopsies.

C4d Deposition after Allogeneic Renal Transplantation in Rats Is Involved in Initial Apoptotic Cell Clearance.

In the context of transplantation, complement activation is associated with poor prognosis and outcome. While complement activation in antibody-mediated rejection is well-known, less is known about complement activation in acute T cell-mediated rejection (TCMR). There is increasing evidence that complement contributes to the clearance of apoptotic debris and tissue repair. In this regard, we have analysed published human kidney biopsy transcriptome data clearly showing upregulated expression of complement factors in TCMR. To clarify whether and how the complement system is activated early during acute TCMR, experimental syngeneic and allogeneic renal transplantations were performed. Using an allogeneic rat renal transplant model, we also observed upregulation of complement factors in TCMR in contrast to healthy kidneys and isograft controls. While staining for C4d was positive, staining with a C3d antibody showed no C3d deposition. FACS analysis of blood showed the absence of alloantibodies that could have explained the C4d deposition. Gene expression pathway analysis showed upregulation of pro-apoptotic factors in TCMR, and apoptotic endothelial cells were detected by ultrastructural analysis. Monocytes/macrophages were found to bind to and phagocytise these apoptotic cells. Therefore, we conclude that early C4d deposition in TCMR may be relevant to the clearance of apoptotic cells.

Pure T-cell mediated rejection following kidney transplant according to response to treatment.

The focus of studies on kidney transplantation (KT) has largely shifted from T-cell mediated rejection (TCMR) to antibody-mediated rejection (ABMR). However, there are still cases of pure acute TCMR in histological reports, even after a long time following transplant. We thus evaluated the impact of pure TCMR on graft survival (GS) according to treatment response. We also performed molecular diagnosis using a molecular microscope diagnostic system on a separate group of 23 patients. A total of 63 patients were divided into non-responders (N = 22) and responders (N = 44). Non-response to rejection treatment was significantly associated with the following factors: glomerular filtration rate (GFR) at biopsy, ΔGFR, TCMR within one year, t score, and IF/TA score. We also found that non-responder vs. responder (OR = 3.31; P = 0.036) and lower GFR at biopsy (OR = 0.56; P = 0.026) were independent risk factors of graft failure. The responders had a significantly superior overall GS rate compared with the non-responders (P = 0.004). Molecular assessment showed a good correlation with histologic diagnosis in ABMR, but not in TCMR. Solitary TCMR was a significant risk factor of graft failure in patients who did not respond to rejection treatment.

MO1001THE OUTCOME OF PLASMA CELL-RICH ACUTE REJECTION IN KIDNEY TRANSPLANTATION, IS IT REALLY POOR?

Abstract Background and Aims The outcome of Plasma cell-rich acute rejection (PCAR) in kidney transplant is reported to be poor. However, PCAR which can be associated with any type of rejection, may not be considered as independent morphological prognostic feature. Different treatment modalities were prescribed with variable responses. We report here four cases of PCAR and describe their presentations, type of rejection, associated conditions and treatment outcome. Method Out of 1920 kidney transplant recipients under follow up in our centre from 1996 till 2019, four patients were reported to have PCAR according to 2007 Banff classification. They were re-evaluated based on 2015 Banff classification. The treatment protocol was tailored according to the type of rejection and associated conditions. Results The four patients, aged 28, 44, 46 and 54 years, had live unrelated renal transplant done somewhere abroad with no data about donor HLA typing. Two of them were females. One had high PRA and she was positive for HBsAg. One patient received induction immunosuppression with basiliximab. They all received prednisolone, mycophenolate and cyclosporine as the maintenance immunosuppression and had immediate graft function. Rejection happened between 23 to 180 months post-transplant. Two patients had acute T-cell mediated Banff 1A rejections with features consistent with early membranous nephropathy. One had acute T-cell mediated rejection Banff 1B and the fourth had borderline T-cell mediated rejection with morphological changes suggestive of chronic active antibody mediated rejection (AMR). Plasma cells constituted 10 to 30% of the interstitial infiltration. All patients received solumedrol pulse. Both patients with features of membranous nephropathy received rituximab and one of them had additionally IVIG. The patient with AMR received plasma exchange and IVIG. However, she did not receive rituximab as she was positive for HBsAg. All patients responded well to treatment and the mean improvement in eGFR was 12.8%, 24.9%, 40.3% and 39.1% at 1-, 3-, 6- and 12-months post treatment. Repeat kidney biopsy at 3 to 12 weeks post treatment showed resolution of plasma cell infiltration in all patients. Conclusion Outcome of PCAR management was favourable among our patients irrespective of the type of rejection and associated conditions.

MO963GRAFT- AND PATIENT-SURVIVAL AFTER FIRST KIDNEY TRANSPLANT BIOPSY

Abstract Background and Aims Kidney transplantation is frequently used as a treatment in uremic patients. However, long term function is not easily predicted. The aim of this study was to investigate to what extent histological diagnosis in the first registered transplant kidney biopsy is related to clinical outcome. Method Included were data of 1463 patients (36.6 % women, 63.4 % men) that were merged from a kidney transplantation register and a biopsy register. These patients obtained their first registered transplant biopsy during the period January 1, 2007 until July 30, 2017. Fisher’s exact test and χ-2 analyses were used for cross-tabulation of data. Graft- and patient-survival analysis was performed by Kaplan-Meier analysis with log-rank tests comparing different groups and in next step age and gender adjusted analysis were performed by multivariate Cox-regression-analysis. Data are presented as Hazard Ratio (HR) and 95% Confidence Intervals (CI). A two-sided p-value of &amp;lt;0.05 was considered as statistically significant. Results The graft-survival was shorter for patients with biopsy-proven glomerular diseases (HR 8.1, CI 3.1-20.7) and rejections (HR 4.3, CI 1.7 -10.5) compared to normal biopsy findings. Further, there was a shorter graft-survival for those with chronic damages (HR 3.2, CI 1.3-8.0), acute tubular injuries (HR 3.0, CI 1.2-7.8), and borderline changes (HR 2.9, CI 1.1-7.6). The patient-survival was reduced for patients with biopsy-proven hematological diseases (HR 9.6, CI 2.1-44.0). Sub analysis of all types of rejections showed shorter graft-survival for chronic T-cell-mediated rejection (TCMR) (HR 4.8, CI 2.1-11.7), active antibody-mediated rejection (ABMR) (HR 4.4, CI 2.1-9.3), chronic ABMR (HR 3.8, CI 2.2-6.7), combined chronic ABMR and TCMR (HR 4.0, CI 2.4-6.9) and other rejections (HR 3.3, CI 1.1-9.6) compared to acute TCMR. Patients with TCMR Banff grade II rejection had a better graft-survival (HR 0.35, CI 0.20-0.63) compared to other rejections as well as patients with TCMR Banff grade I (HR 0.52, CI 0.29-0.93). 265 patients had graft-loss and 42 of those patients died afterwards (15.8%). Of the 42 who died after graft-loss 9 patients died within 30 days after transplant failure (21.4%). Conclusion A shorter graft-survival was found in kidneys with glomerular diseases, rejections, acute tubular injuries, borderline changes and chronic damages. A shorter patient-survival was noted for patients with transplant kidney biopsies with hematological diseases. Patients with Banff grade II rejection had a better graft-survival compared to all other diagnosis and other rejections. Further, awareness should be given to patients the first month after graft-loss.

Six-month risk of Pneumocystis pneumonia following acute cellular rejection: A case-control study in solid organ transplant recipients.

Solid organ transplant (SOT) recipients are at risk of Pneumocystis pneumonia (PCP). PCP is associated with significant morbidity and mortality. The effect of acute T cell-mediated rejection (TCMR) on post-transplant PCP has not been determined yet. In this case-control study, we estimated the risk of PCP following acute TCMR during a lookback period of 180days. We also determined the effects of contributing factors such as CMV infection. We compared 15 SOT (8 kidney, 4 heart, 2 liver, and 1 kidney-pancreas) recipients with PCP with 60 matched recipients who did not develop PCP (control group) during the study period (December 2013 to February 2016). PCP occurred after a complete course of prophylaxis (ie, late-onset PCP) in 60% of patients. Patients with PCP frequently required intensive care unit (ICU) admission (73.3%). Post-transplant PCP was associated with considerable allograft loss (53.4%) and mortality (26.7%). In the 6-month lookback period, acute TCMR (OR: 13.1, 95% CI: 3.2, 53.2), and CMV infection (OR: 15.1,95% CI: 4.0, 53.2.1) were significantly associated with post-transplant PCP. Post-transplant PCP is associated with substantial risk of ICU admission, allograft failure, and mortality. Anti-Pneumocystis prophylaxis for at least 6months following acute TCMR may reduce the risk.