Acute Acute Antibody-mediated Rejection Research Articles

C1q Binding Ability for Prior Risk Assessment of Acute Antibody-Mediated Rejection in ABO-Incompatible Kidney Transplantation.

In ABO blood group incompatible kidney transplantation (ABO-I), potential issues on acute antibody-mediated rejection (ABMR) remain to be solved. This study aimed to assess the risk factors of acute ABMR using recipient- or donor-derived specimens. Quantitative analysis of A/B antigen expression was conducted in 104 donor kidney tissues (Kt), platelets (Plt), and red blood cells (RBC) by immunohistochemical staining or flow cytometry (FCM). ABO-I pre-transplant recipient serum samples (ABMR = 12, non-ABMR = 27) were extracted by propensity score matching. Anti-A antibody titers of IgM, IgG and IgG subclasses, and C1q binding ability (%) on antibody were measured using RBC-FCM. No association was observed between ABMR and A/B antigen expression levels in donor's Plt, RBC, or Kt. In recipient's sample, C1q-IgG binding ability was significantly higher in the ABMR group than in the non-ABMR group (C1q-IgG: 9.04% vs. 5.93% p = 0.049). Neither the A/B antigen expression level in donors (grafts) nor anti-blood group IgG/IgM antibodies in recipient sera before desensitization seemed to influence ABMR incidence in ABO-I. In contrast, C1q-IgG binding ability could be a potential predictor for ABMR in ABO-I.

Long-term isoagglutinin monitoring after ABO-incompatible kidney transplantation.

This study aimed to evaluate whether a 2-week period of daily isoagglutinin titer testing after ABO-incompatible kidney transplantation (ABOi-KT) is sufficient to ensure successful engraftment and to advocate for an extension of the monitoring duration in specific situations. We reviewed patients from January 2022 to December 2023 at Asan Medical Center who underwent therapeutic plasma exchange (TPE) due to elevated ABO antibody titers and suspected acute antibody-mediated rejection (AMR) after ABOi-KT. Data collected included pre- and posttransplantation laboratory results, clinical and procedural information, imaging studies, and needle biopsy results of the renal graft. We encountered 3 cases of acute AMR 2 weeks after transplantation. All cases exhibited simultaneous increases in anti-ABO antibody isoagglutinin titers, creatinine, and C-reactive protein levels. Clinical signs, including fever, suggested possible infection, and renal graft biopsy, confirmed AMR in all cases. Two cases underwent graftectomy, while the third recovered renal function after conservative treatment, including TPE. Our findings suggest that a 2-week monitoring period for isoagglutinin titers after ABOi-KT may not be sufficient to detect late AMR. Extending the monitoring duration and considering lifelong fresh-frozen plasma transfusion with graft-compatible blood types, along with periodic isoagglutinin titer testing in cases of suspected AMR, may improve long-term graft outcomes.

Comparative Analysis of Determinants and Outcome of Early and Late Acute Antibody Mediated Rejection (ABMR).

Antibody-mediated rejection (ABMR) is one of the major determinants of graft survival. Although diagnostic precision and treatment options have improved, response to therapy and graft survival has not improved very significantly. The phenotypes of early and late acute ABMR differ in many ways. In this study, we assessed the clinical characteristics, response to therapy, DSA positivity, and outcomes of early and late ABMR. During the study period, 69 patients with acute ABMR diagnosed on renal graft histopathology were included with a median follow-up of 10 months after rejection. Recipients were stratified into early acute ABMR (<3 months of transplant; n = 29) and late acute ABMR (>3 months of transplant; n = 40). Graft survival, patient survival, response to therapy, and doubling of serum creatinine were assessed and compared between the two groups. Baseline characteristics and immunosuppression protocols were comparable between the early and late ABMR groups. Late acute ABMR had an increased risk of doubling of serum creatinine than the early ABMR group (P = 0.002). Graft and patient survival were not statistically different between the two groups. Response to therapy was inferior in the late acute ABMR group (P = 0.00). Pretransplant DSA was present in 27.6% in the early ABMR group. Late acute ABMR was frequently associated with nonadherence or suboptimal immunosuppression and low DSA positivity (15%). Infections such as CMV, bacterial, and fungal infections were similar in the earlier and late ABMR groups. Late acute ABMR group had a poor response to anti-rejection therapy and also an increased risk of doubling of serum creatinine compared to the early acute ABMR group. There was also a tendency toward increased graft loss in late acute ABMR patients. Late acute ABMR patients are more frequently associated with nonadherence/suboptimal immunosuppression. There was also a low incidence of anti-HLA DSA positivity in late ABMR.

Acute Antibody-mediated Rejection Coexisting With T Cell-mediated Rejection in Pediatric ABO-incompatible Transplantation.

Background.The management and outcome of ABO-incompatible (ABO-I) liver transplantation (LT) has been improving over the past few decades. Recently, the introduction of a pathological evaluation of acute antibody-mediated rejection (AMR) for liver allograft has provided a new recognition of allograft rejection in LT.Methods.One hundred and one pediatric ABO-I LTs performed in our institute were retrospectively analyzed. We assessed the clinical manifestations, diagnosis, and treatment of acute AMR, focusing on the recipient age and pathological findings.Results.Twelve cases (11.9%) of acute AMR related to ABO-I were observed. Nine cases developed mixed T cell–mediated rejection (TCMR)/AMR. These consisted of 6 patients in the younger age group for whom the preconditioning treatment was not indicated and 4 patients in the older age group to whom rituximab was administered as planned. Two patients in the older age group to whom preoperative rituximab was not administered as planned developed isolated AMR. Acute AMR in the older group required plasma exchange for treatment, regardless of the coexistence of TCMR. In contrast, those in the younger group were successfully treated by intravenous methylprednisolone pulse and intravenous immunoglobulin without plasma exchange, accounting for mild immune reaction.Conclusions.Acute ABO-I AMR can develop simultaneously with TCMR, even in young patients with a compromised humoral immune response following ABO-I LT. Establishing the accurate diagnosis of AMR with a pathological examination, including component 4d staining, is crucial for optimizing treatment.

MP36-05 A NOVEL METHOD OF CD31 COMBINED ABO CARBOHYDRATE ANTIGEN MICROARRAY PREDICTS ACUTE ANTIBODY MEDIATED REJECTION IN ABO-INCOMPATIBLE KIDNEY TRANSPLANTATION

You have accessJournal of UrologyCME1 May 2022MP36-05 A NOVEL METHOD OF CD31 COMBINED ABO CARBOHYDRATE ANTIGEN MICROARRAY PREDICTS ACUTE ANTIBODY MEDIATED REJECTION IN ABO-INCOMPATIBLE KIDNEY TRANSPLANTATION Masayuki Tasaki, Hiroaki Tateno, Takashi Sato, Azusa Tomioka, Hiroyuki Kaji, Hisashi Narimatsu, Kazuhide Saito, Toshinari Aoki, Masami Kamimura, Takashi Ushiki, Yutaka Yoshida, Kota Takahashi, and Yoshihiko Tomita Masayuki TasakiMasayuki Tasaki More articles by this author , Hiroaki TatenoHiroaki Tateno More articles by this author , Takashi SatoTakashi Sato More articles by this author , Azusa TomiokaAzusa Tomioka More articles by this author , Hiroyuki KajiHiroyuki Kaji More articles by this author , Hisashi NarimatsuHisashi Narimatsu More articles by this author , Kazuhide SaitoKazuhide Saito More articles by this author , Toshinari AokiToshinari Aoki More articles by this author , Masami KamimuraMasami Kamimura More articles by this author , Takashi UshikiTakashi Ushiki More articles by this author , Yutaka YoshidaYutaka Yoshida More articles by this author , Kota TakahashiKota Takahashi More articles by this author , and Yoshihiko TomitaYoshihiko Tomita More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002590.05AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Isohemagglutinin assays employing red blood cells (RBCs) are the most common assays used to measure antibody titer in ABO-incompatible kidney transplantation (ABOi KTx). However, ABO blood group antigens expressed on RBCs are not identical to those of the kidney due to different proteins linked to ABO carbohydrate antigens. Antibody titers measured by isohemagglutinin assays do not always correlate with clinical outcome and a new method is necessary to precisely predict acute antibody mediated rejection (ABMR) following ABOi KTx. METHODS: We previously reported that CD31 was the most abundant protein linked to ABO carbohydrate antigens on kidney endothelial cells, and developed a new method to measure antibody titer using a microarray of recombinant CD31 (rCD31) linked to ABO carbohydrate antigens (CD31-ABO microarray. Figure 1). To confirm clinical use, a total of 252 plasma samples including volunteers, hemodialysis patients and transplant recipients were examined by both of CD31-ABO microarray and isohemagglutinin assays. RESULTS: Mass spectrometry analysis suggested that rCD31 and native CD31 had similar ABO glycan, meaning CD31-ABO microarray were the mimic of ABO antigens on renal endothelial cells. In transplant recipients, any initial IgG or IgM antibody intensity >30,000 against the donor blood type in the CD31-ABO microarray showed higher sensitivity, specificity, positive predictive value, and negative predictive value to predict acute ABMR following ABOi KTx, compared to isohemagglutinin assays. Representative data were shown in Figure 2 (Blood group A-incompatible). Ten out of 12 patients with ABMR (83.3%) had anti-A IgG Ab levels >30,000 in the CD31-ABO microarray, in contrast, only 1 out of 17 patients without ABMR (5.9%) had anti-A IgG Ab levels >30,000 (Figure 5a). No one had anti-A IgM Ab levels >30,000 in the ABMR (-) group (Figure 5b). CONCLUSIONS: Use of a CD31-ABO microarray will contribute to precisely predicting ABMR following ABOi KTx in advance. Source of Funding: This study was supported by JSPS KAKENHI Grant Number 17K11195 © 2022 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 207Issue Supplement 5May 2022Page: e598 Advertisement Copyright & Permissions© 2022 by American Urological Association Education and Research, Inc.MetricsAuthor Information Masayuki Tasaki More articles by this author Hiroaki Tateno More articles by this author Takashi Sato More articles by this author Azusa Tomioka More articles by this author Hiroyuki Kaji More articles by this author Hisashi Narimatsu More articles by this author Kazuhide Saito More articles by this author Toshinari Aoki More articles by this author Masami Kamimura More articles by this author Takashi Ushiki More articles by this author Yutaka Yoshida More articles by this author Kota Takahashi More articles by this author Yoshihiko Tomita More articles by this author Expand All Advertisement PDF DownloadLoading ...

Synergistic impact of pre-sensitization and delayed graft function on allograft rejection in deceased donor kidney transplantation

The aim of this study is to investigate whether or not delayed graft function (DGF) and pre-transplant sensitization have synergistic adverse effects on allograft outcome after deceased donor kidney transplantation (DDKT) using the Korean Organ Transplantation Registry (KOTRY) database, the nationwide prospective cohort. The study included 1359 cases between May 2014 and June 2019. The cases were divided into 4 subgroups according to pre-sensitization and the development of DGF post-transplant [non-pre-sensitized-DGF(−) (n = 1097), non-pre-sensitized-DGF(+) (n = 127), pre-sensitized-DGF(−) (n = 116), and pre-sensitized-DGF(+) (n = 19)]. We compared the incidence of biopsy-proven allograft rejection (BPAR), time-related change in allograft function, allograft or patient survival, and post-transplant complications across 4 subgroups. The incidence of acute antibody-mediated rejection (ABMR) was significantly higher in the pre-sensitized-DGF(+) subgroup than in other 3 subgroups. In addition, multivariable cox regression analysis demonstrated that pre-sensitization combined with DGF is an independent risk factor for the development of acute ABMR (hazard ratio 4.855, 95% confidence interval 1.499–15.727). Moreover, DGF and pre-sensitization showed significant interaction (p-value for interaction = 0.008). Pre-sensitization combined with DGF did not show significant impact on allograft function, and allograft or patient survival. In conclusion, the combination of pre-sensitization and DGF showed significant synergistic interaction on the development of allograft rejection after DDKT.

Infectious complications and graft outcome following treatment of acute antibody-mediated rejection after kidney transplantation: A nationwide cohort study.

Acute antibody-mediated rejection (AMR) remains a challenge after kidney transplantation (KT). As there is no clear-cut treatment recommendation, accurate information on current therapeutic strategies in real-life practice is needed. KT recipients from the multicenter Swiss Transplant Cohort Study treated for acute AMR during the first post-transplant year were included retrospectively. We aimed at describing the anti-rejection protocols used routinely, as well as patient and graft outcomes, with focus on infectious complications. Overall, 65/1669 (3.9%) KT recipients were treated for 75 episodes of acute AMR. In addition to corticosteroid boluses, most common therapies included plasmapheresis (56.0%), intravenous immunoglobulins (IVIg) (38.7%), rituximab (25.3%), and antithymocyte globulin (22.7%). At least one infectious complication occurred within 6 months from AMR treatment in 63.6% of patients. Plasmapheresis increased the risk of overall (hazard ratio [HR]: 2.89; P-value = 0.002) and opportunistic infection (HR: 5.32; P-value = 0.033). IVIg exerted a protective effect for bacterial infection (HR: 0.29; P-value = 0.053). The recovery of renal function was complete at 3 months after AMR treatment in 67% of episodes. One-year death-censored graft survival was 90.9%. Four patients (6.2%) died during the first year (two due to severe infection). In this nationwide cohort we found significant heterogeneity in therapeutic approaches for acute AMR. Infectious complications were common, particularly among KT recipients receiving plasmapheresis.

Rigetto anticorpo-mediato nel trapianto di rene: fisiopatologia, clinica e terapia

Introduction. Over the past two decades, our thinking has changed from considering rejection as primarily a T-cell mediated process to the realization that insufficient control of the humoral arm of a recipient’s immune system is the factor primarily responsible for the allograft dysfunction and loss. Acute Antibody Mediated Rejection (ABMR) in kidney transplantation is a severe complication that frequently occurs after transplantation and is due either to pre-transplant Donor Specific Antibodies (DSAs) or to de novo DSAs. New techniques to detect DSAs in the recipient serum and advances in the assessment of graft pathology have allowed us to recognize this entity in recent years.&#x0D; Methods. The treatment of ABMR is a multistep process consisting in the desensitization of the patients with preformed antibodies to prevent acute ABMR: in case of acute ABMR, the antibodies are removed from the serum and anti-B cells immunosuppressants are used.&#x0D; Results and Discussion. Along with our knowledge on acute ABMR, a distinct entity has been recognized: the chronic AMBR. Chronic ABMR is a frequent cause of late graft dysfunction and is characterized by a typical histopathologic feature. The treatment is often difficult and new drugs are now tested to control the disease.

Mechanism of Graft Damage Caused by NTPDase1-activated Macrophages in Acute Antibody-Mediated Rejection

ObjectivesTo investigate the effect and mechanism of macrophage activation and graft damage caused by nucleoside triphosphate diphosphohydrolase 1 (NTPDase1) in acute antibody-mediated rejection (AMR). MethodsAcute AMR was induced in different skin-grafted nude mouse models with wild-type NTPDase1 expression, transgene-enhanced NTPDase1 expression, or NTPDase1 gene knockout. Several methods (eg, real-time fluorescence quantitative polymerase chain reaction, high-performance liquid chromatography [HPLC], immunofluorescence, flow cytometry, and luciferin/luciferase assays) were used to study (at the histologic and molecular levels) the extracellular adenosine diphosphate (ADP) concentration, macrophage proliferation, major histocompatibility complex (MHC) class II antigen expression on the surface of macrophages, B-cell activating factor (BAFF) expression in the peripheral blood serum, and the total number of SmIg-positive B cells during acute AMR. The relative activity of NTPDase1 in B cells and epithelial cells, pathologic changes, and the incidence of positive C4d deposition around the capillaries of skin grafts on the different nude mice were studied. ResultsMacrophages proliferated significantly when acute AMR occurred. The higher the NTPDase1 expression level, the lower the extracellular ADP concentration, the expression of MHC class II antigens on the surface of macrophages, the expression of BAFF in the peripheral blood serum, and the total number of SmIg-positive B cells, indicating negative correlations. The relative activity of NTPDase1 in B cells and epithelial cells of the skin graft was different among the different mice. The higher the NTPDase1 expression level, the lower the degree of pathologic damage to the skin graft. ConclusionsImbalance in extracellular ADP degradation by NTPDase1 may promote macrophage activation, and activated macrophages may be an important cause of graft damage.

Prognostic value of C3d-fixing, preformed donor-specific antibodies in crossmatch-positive living kidney transplantation

The occurrence of acute antibody-mediated rejection (ABMR) is higher in flow cytometric crossmatch (FCXM)-positive patients despite desensitization. Accumulating evidence suggests a correlation between the complement-binding ability of donor-specific antibodies (DSAs) and the risk of ABMR. Here, we investigated the correlation between complement C3d-fixing ability of preformed DSA and ABMR risk, the efficacy of a desensitization protocol for patients with C3d-fixing DSA, and the risk of ABMR in 21 DSA- and FCXM-positive patients. We retrospectively analyzed the C3d-fixing ability and mean fluorescence intensity (MFI) of preformed DSA before and after desensitization. Six patients had non-C3d-fixing DSA and 15 had C3d-fixing DSA. The presence of C3d-fixing DSA before desensitization was correlated with the incidence of acute ABMR within 1 year after transplantation (p = .04) and chronic ABMR (p = .03). Moreover, the MFI of preformed DSA differed between responder and non-responder C3d-fixing DSA after desensitization (p < .0001). The C3d-fixing ability of preformed DSA with low MFI disappeared after desensitization. These results indicate that measuring DSA C3d-fixing ability may identify patients with a high risk of ABMR, especially before desensitization. Clinical trial notationUMIN Clinical Trials Registry (UMIN-CTR) number: UMIN000033449.

Bortezomib for Management of Acute Antibody Mediated Rejection Post-Liver Transplantation

Introduction: Acute antibody mediated rejection (AMR) post liver transplaniont (LT) is uncommon and characterized by histopathologic features on liver biopsy, positive c4d stain, and elevated human leucocyte antigen (HLA) donor-specific antibodies (DSA). There is a paucity of literature on the use of Bortezomib for acute AMR in LT. Herein, we present our experience with Bortezomib for management of acute AMR post LT. Methods: Patients who underwent LT and developed acute AMR at a single center from January, 2014 to present were reviewed. Those treated with Bortezomib were included. Results: Two patients developed acute AMR post LT and both patients received Bortezomib for management of acute AMR. Patient 1: 62-year-old female who underwent LT for cirrhosis secondary to hepatitis C. 124 days after LT, patient developed abnormal liver function tests (LFT). Liver biopsy demonstrated acute on chronic rejection and c4d stain was positive. DSA was very high for HLA class II antibodies. DSA remained elevated after pulse steroids. Patient underwent 6 cycles of plasmapheresis (PP) and IVIG with persistently elevated DSA. 145 days after LT, she began Bortezomib (1.3mg/m2 IV) and PP. She received 6 cycles of therapy. DSA 6 days after completion of therapy showed trace HLA class II DSA. Liver biopsy performed 6 days after completion of therapy showed changes of chronic rejection however no cellular infiltrate and C4d stain was negative. Patient 2: 18-year-old male who underwent LT for chronic rejection in a liver graft. 2 days after LT, HLA class II DSA was elevated. Liver biopsy demonstrated a mixed inflammatory infiltrate and c4d stain was positive. He received pulse dose steroids and repeat DSA was elevated. 8 days after OLT, patient received Bortezomib (1.3mg/m2 IV) and PP. He received 4 cycles of therapy. 9 days after last dose of Bortezomib, liver biopsy showed decreased, yet persistent, inflammatory infiltration and c4d stain was positive. Class II DSA remains persistently elevated. Conclusion: Bortezomib appears to have a role in the management of acute AMR in LT recipients. While patient #2 continued to have persistent AMR, he only received 4 cycles of Bortezomib and PP as compared to 6 cycles for patient #1. The literature on the use of Bortezomib in this setting is limited to a single case series of 3 patients. While additional research is required, our study suggests that Bortezomib may be considered as salvage therapy in select patients with acute AMR.

Mechanism of Nucleoside Triphosphate Diphosphohydrolase-1–Associated Imbalance in Adenosine Diphosphate Degradation, B-Cell Activation, and Related Injury During Acute Antibody-Mediated Rejection

ObjectiveThe objective of this study was to investigate the effect of nucleoside triphosphate diphosphohydrolase-1 (NTPDase1) during acute antibody-mediated rejection (AMR). MethodsNTPDase1 overexpression, NTPDase1 knockout, and wild-type nude mice skin graft models were used to induce acute AMR. NTPDase1 expression in B cells, NTPDase1 messenger RNA expression in skin grafts, extracellular adenosine diphosphate (ADP) concentration, B-cell volume and surface antigens expression, average platelet transport rate, and ultrastructure and apoptosis of skin graft cells were investigated. ResultsDuring acute AMR in nude mice, higher NTPDase1 expression caused lower extracellular ADP concentration, smaller increase in B-cell volume, and major histocompatibility complex II surface antigen expression, suggesting a negative correlation between them; higher NTPDase1 expression also caused slower average platelet transport rate and less severe skin graft injury, suggesting a negative correlation between them. Pretreatment with high-dose exogenous NTPDase1 inhibited platelet activation and protected skin grafts, but it resulted in prolonged bleeding time (by 51.4%) and prolonged coagulation time (by 44.1%). ConclusionAn NTPDase1-associated imbalance in extracellular ADP degradation may contribute to B-cell activation, platelet activation, and more severe skin graft injury in nude mice. Pretreatment with high-dose exogenous NTPDase1 effectively protected skin grafts in nude mice at 1 week, but it increased the risk of bleeding.

Prognostic Value of the Persistence of C1q-Binding Anti-HLA Antibodies in Acute Antibody-Mediated Rejection in Kidney Transplantation.

The differential pathogenicity of anti-HLA donor-specific antibodies (DSAs) is not fully understood. The presence of complement-binding DSAs helps in better defining the prognosis of acute antibody-mediated rejection (ABMR). The evolution of these antibodies after the treatment of ABMR is unknown. We included patients from the French multicenter RITUX ERAH study diagnosed with acute ABMR within the first year of renal transplantation, with circulating anti-HLA DSAs and treated randomly by rituximab or placebo (and intravenous immunoglobulins, plasma exchange). We centrally analyzed serum samples at the time of ABMR, 3 and 6 months after ABMR, with anti-HLA DSAs specificities and C1q-binding capacity assessment. Twenty-five patients were included: 68% had C1q-binding DSAs at the time of ABMR. The presence of C1q-binding DSAs was associated with a poorer evolution of chronic glomerulopathy at 6 months (P = 0.036). The persistence of C1q-binding DSAs at 3 and/or 6 months after ABMR was associated with more severe chronic glomerulopathy (P = 0.006), greater C4d score deposition score at 6 months after ABMR (P = 0.008), and graft loss 5 years after ABMR (P = 0.029). C1q-binding capacity was associated with the DSA MFI but 5 C1q-binding DSAs in 4 patients had low MFI values without a prozone effect. The presence and persistence of anti-HLA C1q-binding DSAs after ABMR is a detrimental marker, leading to transplant glomerulopathy and graft loss. Assessment of the complement-binding capacities of DSAs could help decide treatment intensification.

Graft immunologic events in deceased donor kidney transplant recipients with preformed HLA-donor specific antibodies

IntroductionPretransplant donor-specific HLA alloantibodies detected with the Single Antigen Bead (SAB) assay reflect an increased risk for acute antibody-mediated rejection (AMR). We herein report the incidence of both acute AMR and acute cellular rejection (ACR) during the first year posttransplantation, in a cohort of kidney transplant recipients (KTR) of deceased donor (DD) grafts, according to their DSA status. Pretransplant DSA do not preclude DD-KT in negative CDC-XM recipients at our center. Patients and methods246 KT were performed at our center between 01/2012 and 12/2015 and 100 KTR obtained from a DD were analyzed; 24% harbored DSA by SAB assay, MFI values >500 were considered positive. All recipients received thymoglobulin induction and generic tacrolimus-based maintenance therapy. Graft biopsies were performed by protocol on months 3 and 12 as well as per indication. The incidence of AMR and ACR was correlated with the existence of pretransplant DSA. ResultsOverall, 34% of patients developed an acute rejection episode, 54.2% in the DSA group versus 27.6% in the non-DSA group (p=0.032), and most of these events were detected as subclinical conditions in protocol biopsies. AMR events developed in 33.3% and 19.7% (p=0.176) in the DSA and the non-DSA groups, respectively. ACR events were found in 16.6% and 6.6% (p=0.127) in the DSA and non-DSA groups, respectively. Graft function was similar between groups at the end of the 1st year posttransplant and no immunological graft loss occurred. ConclusionDespite the use of depleting induction therapy and adequate tacrolimus trough levels along with MMF and steroids, a high rate of rejection events was observed during the first year post-transplantation.

C1q Test for Identification of Sensitized Liver Recipients at Risk of Early Acute Antibody-Mediated Rejection.

BACKGROUND The majority of liver recipients transplanted with positive crossmatch have a post-transplant course free of acute antibody-mediated rejection (AMR). However, 10% of sensitized recipients develop early severe AMR. There is no clear strategy that would allow for predicting the postoperative course in sensitized liver recipients. One of the possible factors contributing to the dichotomous course in sensitized recipients may be the complement-binding characteristics of the donor-specific antibodies (DSA). MATERIAL AND METHODS We tested sera of sensitized recipients with DSA at the time of transplant, diagnosed with severe AMR or 'AMR-free' for C1q reactivity and strength of mean fluorescence intensity (MFI) in single-antigen beads (SAB) assay. RESULTS Both groups tested positive for DSA C1q binding and DSA-SAB. Recipients with early AMR had significantly stronger DSA MFI in the C1q assay (P<.0001). AMR was observed in patients with very high DSA C1q MFI (22681±8841 vs. the no-AMR group 7954±2061). In SAB assay, DSA MFI strength differences were equivocal (P=0.31). CONCLUSIONS The C1q test is a supportive adjunct in identifying patients at risk of postoperative acute AMR and selects an AMR-free course with 100% negative predictive value despite the presence of DSA.

A model of acute antibody mediated rejection in mouse renal transplantation

Objective To establish a model of acute antibody mediated rejection (AMR) in mouse kidney transplantation. Methods 6-8 weeks old male C3H (H2k) and BALB/c (H2d) mice were used as skin or kidney graft donors and recipients, respectively. All animals were provided by Beijing vital river experimental animal technical limited company. Recipient animals were divided into 2 groups. AMR group, recipient animals were presensitized by transplanting skin grafts before one week of kidney transplantation (n=10). Cell mediated rejection (CMR) group, recipient animals received kidney grafts without being presensitized by skin transplantation (n=10). Normal balb/c mice acted as control (n=3). Animal survival time was recorded and renal allograft function of creatinine (Cr) and blood urea nitrogen (BUN) was monitored. On the fifth day after kidney transplantation, recipient animals were sacrificed, analysis of renal graft histology based on Banff 2013 for rejection diagnosis, immunohistochemistry for mouse IgG, complement fragment C3d deposition detection intragraft, and flow cytometry for circulating donor specific antibody (DSA)-IgG, IgM detection were performed. Results The mean survival time of AMR group was (4.4±1.1) d and longer than 60 days for CMR goup. Graft function of serum Cr [ (415.6±25.6) μmol/L] and BUN [ (2 394.0±94.0) pmol/L] were remarkably increased on postoperative 2 d in AMR group. CMR control group showed normal serum levels of Cr [ (77.8±7.2) μmol/L] and BUN [ (1 343.0±233.9) pmol/L] on 60 days after kidney transplantation. On 5 d after kidney transplantation, the macroscopic morphology of renal grafts in AMR group was significantly swelling while grafts in CMR group were normal. The circulating IgG DSA level in AMR group was remarkably higher than CMR group with mean fluorescence intensity (MFI) values 223.0±29.0 vs. 134.5±39.6. The serum IgM DSA level did not change significantly with MFI values 9.2±0.1 vs. 10.0±0.7. Grafts in AMR group demonstrated dilation of peritubular capillaries (PTC), peritubular capillaritis, glomerulitis, glomerular/tubular necrosis and interstitial inflammation, hemorrhage, and edema. Extensively deposition of IgG and C3d intragraft were also observed in AMR group, while mild changes presented in CMR group which showed no significant difference from the normal control BALB/c mice. Conclusion We successfully established a model of acute AMR in C3H→BALB/c mouse kidney transplantation by presensitizing recipient mice using donor-strain derived skin transplantation at 1 week prior to kidney transplantation, which showed significantly different from non-presensitized recipient mice. Key words: Kidney transplantation; Antibody mediated rejection; Model, animal; Mice

Intravenous immunoglobulin therapy in kidney transplant recipients with de novo DSA: Results of an observational study

BackgroundApproximately 25% of kidney transplant recipients develop de novo anti-HLA donor-specific antibodies (dnDSA) leading to acute antibody-mediated rejection (ABMR) in 30% of patients. Preemptive therapeutic strategies are not available.MethodsWe conducted a prospective observational study including 11 kidney transplant recipients. Inclusion criteria were dnDSA occurring within the first year after transplant and normal allograft biopsy. All patients were treated with high-dose IVIG (2 g/kg 0, 1 and 2 months post-dnDSA). The primary efficacy outcome was incidence of clinical and subclinical acute ABMR within 12 months after dnDSA detection as compared to a historical control group (IVIG-).ResultsAcute ABMR occurred in 2 or 11 patients in the IVIG+ group and in 1 of 9 patients in the IVIG- group. IVIG treatment did not affect either class I or class II DSA, as observed at the end of the follow-up. IVIG treatment significantly decreased FcγRIIA mRNA expression in circulating leukocytes, but did not affect the expression of any other markers of B cell activation.ConclusionsIn this first pilot study including kidney allograft recipients with early dnDSA, preemptive treatment with high-dose IVIG alone did not prevent acute ABMR and had minimal effects on DSA outcome and B cell phenotype.

Treatment of Acute Antibody-Mediated Rejection.

Acute antibody-mediated rejection (AMR) remains an important challenge in the field of kidney transplantation despite the advances in immunosuppressive strategies, and has been recognized as an important cause of allograft dysfunction and graft loss. The treatments of acute AMR are not standardized and poor evidence is currently available on the effectiveness of therapy regimens with combinations of drugs. Standard treatment for acute AMR is based on 3 cornerstones: removal of donor-specific antibodies (DSAs) from the bloodstream, reduction of DSAs synthesis, and inhibition of the interaction between DSAs and human leukocyte antigen antigens on donor's cells. In this paper, we discuss the mechanism of action of the principal drugs currently in use, the main published studies on this topic, and the future insights related to the treatment of acute AMR.

COMPARISON OF DIFFERENT METHODS OF ANTI-HLA ANTIBODIES DETECTION IN DIAGNOSIS OF ANTIBODY-MEDIATED RENAL ALLOGRAFT REJECTION

Aim: to analyze the relationship between circulating anti-HLA antibodies (class-I and class-II), renal pathology and C4d deposition in cases of late acute and chronic antibody-mediated renal allograft rejection according to the method of antibodies detection (ELISA and LUMINEX). Materials and methods. Th e study included 192 patients with indicative graft biopsies (with C4d-staining) and screening detection of anti-HLA antibodies (109 patients by ELISA, 58 patients by LUMINEX, 25 patients – both methods). Patients were divided into 3 groups based on pathology fi ndings: 85 patients with chronic graft rejection, 39 patients with acute antibodymediated rejection (AMR), 68 patients of control group had no signs of AMR. Results. Anti-HLA antibodies (predominantly class-II anti-HLA) were identifi ed in 84.7% of patients with chronic graft rejection, in 84.6% of patients with acute AMR and 33.8% of control group (р &lt; 0.001). Close correlation between the levels of anti￾HLA antibodies detected by different methods was revealed for both classes of antibodies (r² class-I anti-HLA = 0.773, r² class-II anti-HLA = 0.379, р &lt; 0.01). LUMINEX proved to be more sensitive in anti-HLA antibodies detection in all groups. It was especially signifi cant for the diagnosis of C4d-negative acute AMR whose frequen￾cies were 22.2% and 4.8% in detection by LUMINEX and ELISA, respectively (р &lt; 0.01). On the other hand, anti-HLA antibodies being detected by LUMINEX in 55% of patients of the control group more often required determination of donor specifi city. Conclusion. Screening of anti-HLA antibodies (by ELISA and LUMINEX) along with specifi c renal pathology and C4d deposition is suffi cient for the diagnosis of acute and chronic AMR in most cases. Being more sensitive LUMINEX method is preferable for the revealing of C4d-negative AMR, but it requires specifi c DSA detection in many cases.

Optimal Dose of Thymoglobulin for Induction Therapy in High Risk Kidney Transplant Recipients

Background: Thymoglobulin has been used for induction therapy to prevent acute rejection and delayed graft function (DGF) in kidney transplant patients. However, the usual dose of thymoglobulin is considered to be related with frequent infection. We compared the efficacy and safety of low-dose thymoglobulin to high-dose treatment in high risk recipients with kidney transplantation. Methods: Twenty-one kidney transplant recipients underwent induction treatment with thymoglobulin and were divided into two groups: patients treated with low-dose (＜6.0 mg/kg) and high-dose thymoglobulin (≥6.0 mg/kg). All patients showed one or more risk factors for acute rejection or DGF. The risk factors were re-transplantation, recipient or donor age over 60 years, human leukocyte antigen full mismatch, and panel-reactive antibody more than 50%. We compared incidence of acute rejection, infection, hematologic complications, and graft survival between two groups. Results: The demographic characteristics of the two groups were comparable. Mean follow-up duration was 11.9±4.3 months, and cumulative thymoglobulin dosage was 6.3±1.6 mg/kg. The incidence rates of acute antibody-mediated rejection (AMR), DGF and infectious events as cytomegalovirus disease, or urinary tract infection were not significantly different between the two groups. Neutropenia occurred more frequently in the high-dose thymoglobulin group, but there was no statistically significant difference. The rate of graft loss were similar between the two groups. Conclusions: There were no differences in graft survival, infectious disease, and hematologic problems between the two groups. We suggest to lower the dose of thymoglobulin to less than 6 mg/kg for prevent acute AMR and DGF in high risk patients.