C4d Deposition In Peritubular Capillaries Research Articles

Plasma exchange-sensitive syncytial glomerulopathy in a kidney transplant patient.

Microvascular inflammation (MVI), defined as the presence of glomerulitis and/or peritubular capillaritis, is the key histological lesion of anti-HLA donor-specific antibodies (DSA)-related antibody mediated rejection, but recently other possible mechanisms of MVI have emerged. However, except for peritubular capillary C4d deposition that is more frequently observed in the presence of anti-HLA-DSA, histological features are similar regardless of MVI origin. Therefore, accurately describing patterns of MVI may help differentiate etiologies and drive therapeutic choices. We describe the case of a kidney transplant recipient (primary nephropathy: autosomal dominant polycystic kidney disease) who underwent kidney biopsy for worsening renal function and new onset hypertension. Histologic findings showed severe microvascular inflammation with intense glomerulitis and presence of intracapillary multinucleated cells, positive on immunostaining for endothelial marker ETS-related gene (ERG). Focal intense peritubular capillaritis and early glomerular basement membrane reduplication, C4d negative, were observed, consistent with early chronic active ABMR. HLA-DSA were absent, but high level of anti-angiotensin II type-1 receptor (AT1R) antibodies (Ab) were detected (78 U/L, normal levels < 10 U/L). Two subsequent biopsies showed intense microvascular inflammation with diffuse peritubular capillaritis, and multinucleated, ERG-positive, endothelial cells were still seen in glomerular capillary loops. The patient was started on angiotensin receptor blockers (ARBs) and plasma exchange (PEX) sessions obtaining normalization of blood pressure and AT1R Ab and proteinuria reduction, but, after subsequent liver transplant, rituximab therapy failed to maintain remission and the patient remained PEX-dependent.

Complement C4d as a biomarker for systemic lupus erythematosus and lupus nephritis.

Background: Increasing studies in the last decade have led to the widespread understanding that C4d, a split product of complement component 4 (C4), is a potential biomarker for systemic lupus erythematosus (SLE) and lupus nephritis (LN).Purpose: The aim of this review is to summarize the highlights of studies investigating the use of C4d as a biomarker for diagnosing and monitoring SLE and LN patients.Data collection: we searched PubMed/Medline and Wanfang databases using the terms "C4d and systemic lupus erythematosus", "C4d and lupus nephritis", and "Complement C4d".Results: The deposition of C4d on circulating blood cells has been shown in several clinical studies to be a potential diagnostic marker that can be used to monitor patients with SLE. In addition, C4d deposits on circulating blood cells may be a helpful diagnostic marker for LN, one of the most severe complications of SLE. Meanwhile, studies utilizing renal biopsy specimens have indicated that C4d deposition in the renal peritubular capillaries of LN patients may predict more severe LN or a worse patient prognosis. Generally, a high plasma C4d level and a high plasma C4d/C4 ratio may also be promising indicators that can be used to monitor patients with SLE and LN.Conclusions: C4d detection may be a novel strategy for further clinical prediction and therapy.

Microvascular inflammation in the absence of human leukocyte antigen-donor-specific antibody and C4d: An orphan category in Banff classification with cytotoxic T and natural killer cell infiltration

Isolated microvascular inflammation (iMVI) without HLA donor-specific antibodies or C4d deposition in peritubular capillaries remains an enigmatic phenotype that cannot be categorized as antibody-mediated rejection (ABMR) in recent Banff classifications. We included 221 kidney transplant recipients with biopsies with ABMR (n = 73), iMVI (n = 32), and normal (n = 116) diagnoses. We compared peripheral blood leukocyte distribution by flow cytometry and inflammatory infiltrates in kidney transplant biopsies among groups. Flow cytometry showed fewer lymphocytes and total, CD4+, and CD8+ peripheral T cells in iMVI compared with ABMR and normal cases. ABMR and iMVI had fewer total natural Killer (NK) cells but more NKG2A+ NK cells. Immunohistochemistry indicated that ABMR and iMVI had greater CD3+ and CD68+ glomerular infiltration than normal biopsies, whereas CD8+ and TIA1+ cells showed only increased iMVI, suggesting they are cytotoxic T cells. Peritubular capillaries displayed more CD3+, CD56+, TIA1+, and CD68+ cells in both ABMR and iMVI. In contrast, iMVI had less plasma cell infiltration in peritubular capillaries and interstitial aggregates than ABMR. iMVI displayed decreased circulating T and NK cells mirrored by T cell and NK cell infiltration in the renal allograft, similar to ABMR. However, the lesser plasma cell infiltration in iMVI may suggest an antibody-independent underlying stimulus.

332.4: Microvascular Injury With Macrophage, Neutrophil, And Hla-dr Positive Inflammatory Infiltrate, either in dsa Positive or Negative abmr, Determines the Prognosis in Renal Allografts

Introduction: Antibody-mediated rejection (ABMR) has well-defined histomorphological lesions, like linear C4d staining or microvascular inflammation [(g + ptc) ≥ 2] in peritubular capillaries (PTCs). Although these histologic features of ABMR (ABMRh) are usually compatible with donor-specific antibodies (DSA), it is demonstrated that recipients can develop ABMRh in the absence of DSAs. Indeed, DSA can not be found in 40-60% of patients with marked microvascular inflammation (MVI). We aimed to investigate the relationship between PTC macrophage (M), neutrophil, and HLA-DR positive cell infiltration with variable clinical presentations of ABMR. Methods: A total of 125 patients with acute ABMR were categorized into four groups; Group 1: DSA (+) ABMR, Group 2: DSA (-) ABMR, Group 3: DSA (+) mixed rejection (ABMR+vascular rejection), and Group 4: DSA (-) mixed rejection. The degree of the glomerular and PTC macrophage (CD68+), neutrophil, and HLA-DR positive cells was graded. The loss of HLA-DR expression in PTC endothelium was accepted as PTC destruction. The follow-up biopsies were evaluated for the development of diffuse interstitial fibrosis (IF) and transplant glomerulopathy (TG). Results: The type of ABMR showed a significant correlation with PTC C4d expression, the presence of TMA, PTC destruction, microvascular (PTC and glomerular) macrophage, neutrophil, and DR+ cell infiltration (p<0.01 for all). Group 3 showed the highest microvascular inflammation, PTC destruction, C4d expression, and TMA. Groups 4, 1, and 2 followed Group 3, respectively, and Group 2 showed the best outcome. Also, patients in Group 3 developed the highest and earliest IF and TG development during follow-up (p<0.01). Similarly, Groups 4, 1, and 2 followed Group 3 regarding the development of IF and TG development. PTC C4d staining intensity significantly correlated with PTC destruction and DSA positivity (p<0.001). Overall 5-year graft survival was 86%, 51%, 45%, and 26% for Groups 2, 1, 4, and 3, respectively (p<0.001). Overall 5-year graft survival was 87%, 54%, and 20% for patients with grades 1, 2, and 3 PTC destruction, respectively (p<0.001). Additionally, overall 5-year survival was 100%, 81%, and 21% for grades 1, 2, and 3 C4d depositions in PTCs, respectively (P<0.001). Conclusion: ABMRh comprising characteristic histologic findings without detectable DSA represent a distinct phenotype with superior renal allograft survival than ABMRh with positive DSA. Additionally, PTC C4d deposition and the resulting PTC destruction were shown to significantly indicate graft failure and poor prognosis independent of the DSA positivity. Therefore, we concluded that ABMR should be divided into different subgroups for treatment, considering the presence of DSA and vascular rejection.

Association of HLA Mismatches and Histology Suggestive of Antibody-Mediated Injury in the Absence of Donor-Specific Anti-HLA Antibodies.

The histology of antibody-mediated rejection after kidney transplantation is observed frequently in the absence of detectable donor-specific anti-HLA antibodies. Although there is an active interest in the role of non-HLA antibodies in this phenotype, it remains unknown whether HLA mismatches play an antibody-independent role in this phenotype of microcirculation inflammation. To study this, we used the tools HLAMatchmaker, three-dimensional electrostatic mismatch score, HLA solvent accessible amino acid mismatches, and mismatched donor HLA-derived T cell epitope targets to determine the degree of HLA molecular mismatches in 893 kidney transplant recipients with available biopsy follow-up. Multivariable Cox proportional hazards models were applied to quantify the cause-specific hazard ratios of the different types of HLA mismatch scores for developing antibody-mediated rejection or histology of antibody-mediated rejection in the absence of donor-specific anti-HLA antibodies. In all survival analyses, the patients were censored at the time of the last biopsy. In total, 121 (14%) patients developed histology of antibody-mediated rejection in the absence of donor-specific anti-HLA antibodies, of which 44 (36%) patients had concomitant T cell-mediated rejection. In multivariable Cox analysis, all different calculations of the degree of HLA mismatch associated with developing histology of antibody-mediated rejection in the absence of donor-specific anti-HLA antibodies. This association was dependent neither on the presence of missing self (potentially related to natural killer cell activation) nor on the formation of de novo HLA antibodies. Also, glomerulitis and complement C4d deposition in peritubular capillaries associated with the degree of HLA mismatch in the absence of anti-HLA antibodies. The histology of antibody-mediated rejection and its defining lesions are also observed in patients without circulating anti-HLA antibodies and relate to the degree of HLA mismatch.

Clinical significance of low pre-transplant donor specific antibodies (DSA) in living donor kidney recipients with negative complement-dependent cytotoxicity crossmatches (CDCXM), and negative flow cytometry crossmatches (FLXM) – A single-center experience

BackgroundIt is controversial whether all donor-specific antibodies (DSA) detected by the solid-phase single antigen bead (SAB) assay negatively affect kidney transplantation outcomes. The study aimed to evaluate the possible clinical significance of low pre-transplant DSA in living donor kidney recipients. We analyzed a group of patients with HLA-A, B, and -DR DSA reactivities below a virtual crossmatch (VXM) value of 5000 MFI but with all VXM DSA reactivities at HLA-DQ, -DP, and -Cw, which were not typed routinely for donors prior to transplantation. We also investigated the incidence of persistent and de novo DSAs in available posttransplant SAB assays. MethodsFrom the historical cohort of living donor recipients transplanted between 2014 and 2018 at our center (n = 82), 55 patients met the inclusion criteria, namely: these patients were > 18 years old with non-HLA identical sibling donors, who were not desensitized, who had available pre-transplant SAB results, and who had negative both complement-dependent cytotoxicity crossmatch (CDCXM) and flow cytometry crossmatch (FLXM) results. An additional donor HLA typing, performed for all 55 recipients, identified donor additional HLA-DQ, -DP, and -Cw DSA reactivities. These patients were then divided by SAB reactivity into three groups: 1) those with DSA-positive reactivities; 2) those with non-donor-specific anti-HLA reactivities (NDSA); and, 3) those who were anti-HLA-negative. All these recipients were followed for three years and checked for their de novo or persistent DSA. ResultsIn the studied cohort, DSA-positive, NDSA reactive, and anti-HLA negative recipients constituted 33%, 36%, and 31% of 55 patients, respectively. Non-routinely considered pre-transplant HLA-DQ, -DP, and -Cw DSA-positive reactivities were shown in as many as 78% of DSA-positive cases (group 1) with the lowest MFI value of 319 to DP4 and the highest MFI of 5767 to DQ2. Of the pre-transplant HLA-A, B, and -DR DSA reactivities, only -DR52 DSA reactivity reached the highest MFI value of 2191. These detected DSAs did not reduce the mean estimated glomerular filtration rate (eGFR) values and did not increase the incidence of proteinuria in recipients. While the 3-year graft survival was lower in the DSA-positive group (94.4%) with one recipient who lost kidney transplant, the difference was not significantly different (p = 0.7) from the NDSA (100%) and negative (100%) groups. In terms of the incidence of de novo acute antibody-mediated rejection (AMR) at three years after transplantation, no case has been reported in the cohort. This may suggest that low DSA-positive recipients do not experience higher rejection rate. However, DSA-positive recipients had a tendency for a higher frequency of C4d deposits in peritubular capillaries (PTC) and de novo DSA. ConclusionOur 3-year follow-up of patients with low pre-transplant DSA found no association with a deterioration in graft function and worse graft survival. Furthermore, we did not observe an increase in AMR in our patients with low DSA. A larger cohort and a longer follow-up period may be needed to evaluate the tendency of low DSA-positive recipients towards the higher incidence of C4d deposits in PTC and/or de novo DSA.

Donor-specific antibodies, glomerulitis, and human leukocyte antigen B eplet mismatch are risk factors for peritubular capillary C4d deposition in renal allografts.

Background:The complement system plays an important role in the immune response to transplantation, and the diagnostic significance of peritubular capillary (PTC) C4d deposition (C4d+) in grafts is controversial. The study aimed to fully investigate the risk factors for PTC C4d+ and analyze its significance in biopsy pathology of kidney transplantation.Methods:This retrospective study included 124 cases of kidney transplant with graft biopsy and donor-specific antibody (DSA) testing from January 2017 to December 2019 in a single center. The effects of recipient pathological indicators, eplet mismatch (MM), and DSAs on PTC C4d+ were examined using univariate and multivariate logistic regression analyses.Results:In total, 35/124 (28%) were PTC C4d+, including 21 with antibody-mediated rejection (AMR), eight with renal tubular injury, three with T cell-mediated rejection, one with glomerular disease, and two others. Univariate analysis revealed that DSAs (P < 0.001), glomerulitis (P < 0.001), peritubular capillaritis (P < 0.001), and human leukocyte antigen (HLA) B eplet MM (P = 0.010) were the influencing factors of PTC C4d+. According to multivariate analysis, DSAs (odds ratio [OR]: 9.608, 95% confidence interval [CI]: 2.742–33.668, P < 0.001), glomerulitis (OR: 3.581, 95%CI: 1.246–10.289, P = 0.018), and HLA B eplet MM (OR: 1.166, 95%CI: 1.005–1.353, P = 0.042) were the independent risk factors for PTC C4d+. In receiver operating characteristic curve analysis, the area under the curve was increased to 0.831 for predicting PTC C4d+ when considering glomerulitis, DSAs, and HLA B eplet MM. The proportions of HLA I DSAs and PTC C4d+ in active antibody-mediated rejection were 12/17 and 15/17, respectively; the proportions of HLA class II DSAs and PTC C4d+ in chronic AMR were 8/12 and 7/12, respectively. Furthermore, the higher the PTC C4d+ score was, the more serious the urinary occult blood and proteinuria of recipients at the time of biopsy.Conclusions:PTC C4d+ was mainly observed in AMR cases. DSAs, glomerulitis, and HLA B eplet MM are the independent risk factors for PTC C4d+.

Antibody-suppressor CD8+ T cells ameliorate antibody-mediated rejection following kidney transplant in mice

Abstract Purpose CCR5 KO kidney transplant (KT) mice produce high titer alloantibody (alloAb) associated with severe antibody-mediated rejection (AMR) that reproduces AMR histology observed in human KT recipients. We previously reported the novel alloAb suppressor activity of alloprimed CXCR5+IFNγ+CD8+ T (Tab-supp) cells following hepatocellular transplant in mice. Here, we investigated the biologic impact of alloprimed CD8+ Tab-supp cells and their capacity to suppress alloAb following adoptive cell transfer (ACT) into CCR5 KO KT mice. Methods CCR5 KO (H-2b) mice were transplanted with allogeneic A/J (H-2a) kidneys, and on postoperative day (POD) 5 underwent ACT of alloprimed CD8+ Tab-supp cells (retrieved from C57BL/6 mice alloprimed with A/J alloantigen). A second cohort received concomitant bilateral native nephrectomy, and allograft survival was monitored with serial serum creatinine (&amp;gt;100 μmol/L defines KT graft loss). Untreated CCR5 KO KT mice served as controls. Results CCR5 KO KT mice developed high alloAb titer compared to wild-type (WT) recipients (5,800±700 vs 1,200±100; p=0.0003). ACT significantly inhibited alloAb production by 5-fold (1,200±200; p&amp;lt;0.0001) and POD14 AMR pathology (peritubular capillary margination and C4d deposition, arteritis) in CCR5 KO KT mice (composite histologic score 3.6±1.5 vs 8.4±0.2 in untreated controls; p=0.006). Following ACT, alloAb remained suppressed beyond POD 30, correlating with enhanced allograft survival (MST 52 vs 14 days; p=0.006). Conclusion ACT of CD8+ Tab-supp cells effectively inhibits alloAb production and AMR not only after allogeneic hepatocellular transplant, but also after vascularized solid organ transplant such as in CCR5 KO KT recipients.

Association of c4d deposition in renal allograft biopsy with morphologic features in Banff diagnosis

Association of c4d deposition in renal allograft biopsy with morphologic features in Banff diagnosis - IJPO- Print ISSN No: - 2394-6784 Online ISSN No:- 2394-6792 Article DOI No:- 10.18231/j.ijpo.2019.033, Indian Journal of Pathology and Oncology-Indian J Pathol Oncol

C5b9 Deposition in Glomerular Capillaries Is Associated With Poor Kidney Allograft Survival in Antibody-Mediated Rejection.

C4d deposition in peritubular capillaries (PTC) reflects complement activation in antibody-mediated rejection (ABMR) of kidney allograft. However, its association with allograft survival is controversial. We hypothesized that capillary deposition of C5b9—indicative of complement-mediated injury—is a severity marker of ABMR. This pilot study aimed to determine the frequency, location and prognostic impact of these deposits in ABMR. We retrospectively selected patients diagnosed with ABMR in two French transplantation centers from January 2005 to December 2014 and performed C4d and C5b9 staining by immunohistochemistry. Fifty-four patients were included. Median follow-up was 52.5 (34.25–73.5) months. Thirteen patients (24%) had C5b9 deposits along glomerular capillaries (GC). Among these, seven (54%) had a global and diffuse staining pattern. Twelve of the C5b9+ patients also had deposition of C4d in GC and PTC. C4d deposits along GC and PTC were not associated with death-censored allograft survival (p = 0.42 and 0.69, respectively). However, death-censored allograft survival was significantly lower in patients with global and diffuse deposition of C5b9 in GC than those with a segmental pattern or no deposition (median survival after ABMR diagnosis, 6 months, 40.5 months and 44 months, respectively; p = 0.015). Double contour of glomerular basement membrane was diagnosed earlier after transplantation in C5b9+ ABMR than in C5b9– ABMR (median time after transplantation, 28 vs. 85 months; p = 0.058). In conclusion, we identified a new pattern of C5b9+ ABMR, associated with early onset of glomerular basement membrane duplication and poor allograft survival. Complement inhibitors might be a therapeutic option for this subgroup of patients.

Histological picture of antibody-mediated rejection without donor-specific anti-HLA antibodies: Clinical presentation and implications for outcome.

In this cohort study (n=935 transplantations), we investigated the phenotype and risk of graft failure in patients with histological criteria for antibody-mediated rejection (ABMR) in the absence of circulating donor-specific anti-human leukocyte antigen (HLA) antibodies (DSA), and compared this to patients with definite ABMR and HLA-DSA-positivity. The histological picture did not differ between HLA-DSA-positive (n=85) and HLA-DSA-negative (n=123) cases of ABMR histology, apart from increased complement split product 4d (C4d) deposition in the peritubular capillaries in HLA-DSA-positive cases. Histology of ABMR without HLA-DSA was more transient than DSA-positive ABMR, and patients with ABMR histology without HLA-DSA had graft survival superior to that of HLA-DSA-positive patients, independent of concomitant T cell-mediated rejection (38.2%) or borderline changes (17.9%). Multivariate analysis showed that the risk of graft failure was not higher in patients with histological picture of ABMR (ABMRh ) in the absence of HLA-DSA, compared to patients without ABMRh . Despite an association between C4d deposition and HLA-DSA-positivity, using C4d deposition as alternative for the DSA criterion in the diagnosis of ABMR, as proposed in Banff 2017, did not contribute to the prognosis of graft function and graft failure. We concluded that biopsies with ABMRh but without detectable HLA-DSA represent a distinct, often transient phenotype with superior allograft survival.

The relationship between pathologic lesions of active and chronic antibody-mediated rejection in renal allografts.

The Banff classification of renal allograft pathology defines specific morphologic lesions that are used in the diagnosis of active (glomerulitis, peritubular capillaritis, endarteritis) and chronic (transplant glomerulopathy, peritubular capillary basement membrane multilayering, transplant arteriopathy) antibody-mediated rejection (ABMR). However, none of these individual lesions are specific for ABMR, and for this reason Banff requires 1 or more additional findings, including C4d deposition in peritubular capillaries, presence of circulating donor-specific antibodies (DSAs), and/or expression in the tissue of transcripts strongly associated with ABMR, for a definitive diagnosis of ABMR to be made. In addition, while animal studies examining serial biopsies have established the progression of morphologic lesions of active to chronic ABMR as well as intermediate forms (chronic active ABMR) exhibiting features of both, clear documentation that lesions of chronic ABMR require the earlier presence of corresponding active and intermediate lesions is less well established in human renal allografts. This review examines temporal relationships between key morphologic lesions of active and chronic ABMR in biopsies of human grafts, likely intermediate forms, and findings for and possibly against direct and potentially interruptible progression from active to chronic lesions.

Outcomes of Prolonged Treatment With Intravenous Immunoglobulin Infusions for Acute Antibody-mediated Rejection in Kidney Transplant Recipients

BackgroundTreatment of antibody-mediated rejection (AMR) is one of the main problems after kidney transplantation (KTx). The results of intensive AMR treatment with plasmapheresis (PF) and repeated infusions of intravenous immunoglobulin (IVIg) are presented. MethodsDiagnosis of AMR was based on graft biopsy and the presence of donor-specific antibodies (DSAs). AMR therapy consisted of 5 PF and IVIg infusions given after the last PF. Subsequent IVIg doses were given every 4 weeks for 6 months. Graft biopsy and DSA assessment were repeated at the end of the treatment (ET). ResultsFour women and 10 men were included in our study; mean time from KTx to AMR was 79 (range, 3–193) months. During the treatment, 4 patients had graft failure. Graft function at baseline was significantly worse (P = .02) in this group compared with patients who completed the therapy. At baseline, mean flourescence intensity (MFI) was 6574 (range, 852–15,917) in the whole group, 7088 (range, 1054–15,917) in patients who completed treatment, and 4828 (range, 852–11,797) in patients who restarted hemodialysis. At ET, DSA MFI decreased in 8 of 10 patients (80%) who completed the therapy. The MFI decrease was 3946 (range, 959–11,203). Control graft biopsies revealed decreased intensity of C4d deposits in peritubular capillaries in 7 patients (78%) and decreased peritubular capillaritis in 2 patients (22%). ConclusionIntensive, prolonged AMR therapy with PF and IVIg resulted in a decrease in DSA titer and intensity of C4d deposits, but was not associated with reduction of microcirculation inflammation. Treatment was ineffective in patients with baseline advanced graft insufficiency.

Markers of Endothelial-to-Mesenchymal Transition: Evidence for Antibody-Endothelium Interaction during Antibody-Mediated Rejection in Kidney Recipients.

Antibody-mediated rejection (ABMR) is a leading cause of allograft loss. Treatment efficacy depends on accurate diagnosis at an early stage. However, sensitive and reliable markers of antibody-endothelium interaction during ABMR are not available for routine use. Using immunohistochemistry, we retrospectively studied the diagnostic value of three markers of endothelial-to-mesenchymal transition (EndMT), fascin1, vimentin, and heat shock protein 47, for ABMR in 53 renal transplant biopsy specimens, including 20 ABMR specimens, 24 cell-mediated rejection specimens, and nine normal grafts. We validated our results in an independent set of 74 unselected biopsy specimens. Endothelial cells of the peritubular capillaries in grafts with ABMR expressed fascin1, vimentin, and heat shock protein 47 strongly, whereas those from normal renal grafts did not. The level of EndMT marker expression was significantly associated with current ABMR criteria, including capillaritis, glomerulitis, peritubular capillary C4d deposition, and donor-specific antibodies. These markers allowed us to identify C4d-negative ABMR and to predict late occurrence of disease. EndMT markers were more specific than capillaritis for the diagnosis and prognosis of ABMR and predicted late (up to 4 years after biopsy) renal graft dysfunction and proteinuria. In the independent set of 74 renal graft biopsy specimens, the EndMT markers for the diagnosis of ABMR had a sensitivity of 100% and a specificity of 85%. Fascin1 expression in peritubular capillaries was also induced in a rat model of ABMR. In conclusion, EndMT markers are a sensitive and reliable diagnostic tool for detecting endothelial activation during ABMR and predicting late loss of allograft function.

G486(P) First successful paediatric hla incompatible renal transplantation in the united kingdom

Aims To report the successful outcome of HLA incompatible renal transplantation using plasmapheresis and intravenous immunoglobulin (on day –1) and quadruple immunosuppression with anti–thymocyte globulin (1.5 mg/kg day 1–4), corticosteroids, mycophenolate mofetil and tacrolimus (from day -7). Methods Six month follow–up data of 14–year old young lady who underwent living related ABO compatible (O into B) and HLA incompatible renal transplantation from her father (mismatch 0,1,1) for end-stage kidney disease on peritoneal dialysis secondary to congenital abnormalities of the kidney and urinary tract with bilateral renal dysplasia, recurrent urinary tract infections, bilateral vesico–ureteric reflux after left ureteric reimplantation and right nephrectomy. She had a previous failed renal transplantation at 11 years of age with primary non–function due to intra-renal thrombosis (no acute rejection or TMA) requiring transplant nephrectomy the day after transplantation with 95–100% calculated reaction frequency due to HLA antibodies, specific for mismatches HLA B7 and DQ8 against father with B cell positive (T cell negative) crossmatch which was reduced to negative with test plasma exchange and reduction in MFI from 16,200 to 6,480 and from 11,602 to 4,625 on the day prior to transplantation. She had no offers from the deceased donor waiting list or via the paired exchange scheme (NLDKSS). Results Successful renal transplant without further antibody removal or surgical complications with six month follow–up data with stable renal allograft function with eGFR of 60–96 mls/min/1.73m 2 , 12-hour trough tacrolimus and mycophenolate levels of 7.3 mcg/l and 3.0 mg/l respectively, controlled hypertension on one anti-hypertensive agent with minimal albuminuria (17.4 mg/mmol). Her DSA reduced to 4,691on day 2 but increased further to 23,772 to 38,630 during weeks 1 to 3 and have stabilised out at 21,246 to 22,168 (B7 and DQ8 of 8,407 and 13,761 respectively). She has had three percutaneous renal transplant biopsies at weeks 2, 7 and 11 without acute rejection or IFTA but moderate concentric fibrous intimal thickening of large muscular arteries and C4d deposition in peritubular capillaries and glomeruli. Conclusions This is the first paediatric HLA incompatible renal transplantation in UK and highlights that clinicians must consider this option in ESKD patients whose living donors have been excluded due to HLA incompatibility.

C4d Deposits in Borderline Rejection: An Early Marker for Chronic Renal Dysfunction?

The impact of borderline rejection in renal graft remains controversial. The aim of this study was to analyze the presence of C4d deposits in peritubular capillaries and macrophage infiltration in renal biopsies with diagnosis of borderline rejection ant its effect on graft function. Thirty-one renal transplant recipients with a diagnosis of borderline rejection were included. Initial and sequential biopsies were analyzed for morphology, C4d, and macrophage staining and compared with clinical data. Initial biopsies showed 12 samples to be C4d positive, associated with a higher incidence of delayed graft function, earlier post-transplantation time, higher acute tubular necrosis score, capillaritis, and glomerular macrophage infiltration, and a lower level of tubulitis, interstitial fibrosis, and tubular atrophy compared with the C4d-negative samples. In sequential biopsies, 5 patients from the negative group turned C4d positive. Patients with ≥1 positive C4d biopsy (n = 17) showed lower renal graft function at 6 months (1.8 ± 0.8 vs 1.4 ± 0.5 mg/dL; P < .01), 1 year (2.1 ± 1 vs 1.5 ± 0.5 mg/dL; P < .01), and 2 years (2.3 ± 1.3 vs 1.5 ± 0.7 mg/dL; P < .05) of follow-up. The expression of C4d in peritubular capillaries of renal biopsies classified as borderline rejection was associated with a worse prognosis for the renal allograft.

Prevalence of Donor-Specific Anti-HLA Antibodies and C4 d Deposits in Pediatric Renal Transplant Recipients: Serological /histological Correlations and Impact On Graft Function and Survival.

Introduction: Donor-specific anti-HLA antibodies (DSA) and C4d deposits in peritubular capillaries are associated with humoral rejection and graft loss. Aim: To assess in children with a renal transplant (RTX) who underwent a biopsy due to creeping creatinine ≥ 30% during 3 to 12 months previously: 1. Prevalence of DSA and C4d. 2. Graft survival according to histopathological diagnosis (Banff). 3. Risk factors of graft loss and DSA post RTX. Patients and Methods Between December 1998 and March 2013 700 RTX were performed. The clinical charts of children who underwent a kidney biopsy were retrospectively assessed. Results: Ninety-two children, 53 boys, were included in the study. Mean age at RTX was 9.6±3 years; 68 received a deceased donor (DD) organ; 90 had a first RTX, with a biopsy at a mean of 38 months post RTX (IQR: 20-66). Follow-up was 6.3± 3 years. Baseline immunosuppression was steroids, MMF/MPS and CsA (n=74), TAC (n=10), and SRL (n=8); DD RTX recipients received thymoglobulin induction. DSA (Luminex) were detected in 48%, diffuse C4d (IFI) in 48% and focal C4d in 27%. DSA were found in 93% of C4d-positive vs. 7% of C4d-negative biopsies (p<0.001) Histopathology: Chronic rejection (CR): n=53 with Transplant Glomerylopathy n=7, IFTA n=31, ACR n=4, others n=4. Graft survival at 12 years: IFTA 96%, CR: 53% (p: 0.02). Risk factors for graft loss (multivariate analysis): Acute tubular necrosis: (HR 7.3, 95%CI: 1.7-31), Chronic rejection with ACR: (HR 4.6, 95%CI:1.6-12.5), and age at RTX (HR 1.2: 95%CI: 1.2-1.5). Risk factors for post RTX DSA: No-adherence(OR: 6.9, 95CI%: 2.3-20), and peritubular capillaritis (HR: 2.4 IC95%, 1.5-19.9). Conclusion: Antibody-mediated damage was common in children with graft failure. Significant association was found between microvascular inflammation, no-adherence and the presence of DSA. Vascular rejection and concomitant ACR, acute tubular necrosis, and age at RTX were predictors of graft loss.

Early Versus Late Acute Antibody-Mediated Rejection in Thai Kidney Transplant Patients: The Two Distinct Clinical Syndromes.

Background: Acute antibody-mediated rejection (AMR) is the leading cause of early and late renal allograft dysfunction. The purpose of this study was to compare the clinico-pathological features between early and late acute AMR in Thai kidney transplant patients. Method: We examined our kidney transplant recipients for acute AMR demonstrated on biopsy between January 2005 and December 2013. Patients who had glomerulitis and/or peritubular capillaritis were enrolled and stratified by early (≤ 3 months) and late acute AMR (> 3 months after transplantation). Results: Of 64 patients with biopsy-proven acute AMR, 27 cases of early acute AMR were analyzed for associated factors compared with 37 cases of late acute AMR. Early acute AMR was more common in older patients (46.5 ± 10.0 vs. 34.9 ± 9.8; p < 0.001), female recipients (66.7% vs. 32.4%; p = 0.007), deceased donor allografts (70.4% vs. 37.8%; p = 0.01), and highly sensitized patients (74.1% vs. 13.5%; p = 0.01). Non-adherence was observed in 9 cases (24.3%) with late acute AMR whereas none with early acute AMR (p = 0.01). Endothelialitis was more prevalent in early acute AMR (77.8% vs. 10.8%; p < 0.001). Transplant glomerulopathy and interstitial fibrosis/tubular atrophy, the pathological features of chronic changes, were already demonstrated in late acute AMR (70.3% and 13.5%, respectively) but none in early acute AMR (p < 0.001 and 0.05, respectively). Peritubular capillary C4d deposition were commonly revealed in late acute (70.3% vs. 25.9%; p <0.001, respectively). Donor specific antibodies (DSA) were significantly evidenced in late acute AMR (67.6% vs 37%; p = 0.01). Anti-HLA class II (mostly anti-HLA DQ) was more common than class I (62.2% vs 21.6%; p = 0.003) in late acute AMR while anti-HLA class I (mostly anti-HLA A) was more prevalent than class II (29.6% vs 11.1%; p = 0.09) in early acute AMR. The patients with stable graft function at one year after anti-humoral treatment were observed in 21 cases (77.8%) with early acute AMR but only 13 cases (35.1%) with late acute AMR (p = 0.001). Conclusion: Despite similar pathological findings, early and late acute AMR are distinct clinical syndromes. Late acute AMR has worse prognosis than early acute AMR.

Using Markers of Endothelial to Mesenchymal Transition to Detect Endothelial Activation in Kidney Recipients With Antibody Mediated Rejection.

Introduction: Antibody-mediated rejection (ABMR) is a leading cause of allograft loss. The efficacy of treatment depends on an accurate diagnosis at an early stage. Sensitive and reliable markers are still lacking. Methods: Using immunohistochemistry, we retrospectively studied the diagnostic value of endothelial-to-mesenchymal transition (EndMT) markers for ABMR in 53 renal transplant biopsies including 20 ABMR, 24 with cell-mediated rejection and 9 normal grafts. We validated our results in a second independent set of 72 non-selective biopsies. Results: The markers of EndMT were very strongly expressed in the endothelial cells of peritubular capillaries in grafts with ABMR, and absent in normal renal grafts. The level of expression of EndMT markers was significantly associated with current ABMR criteria such as capillaritis (rho=0.6, p<0.0001), glomerulitis (rho=0.5, p=0.0002), peritubular capillary c4d deposition (mean of EndMT score=3.44±0.18 vs 1.8±0.24 for c4d+ for c4d- groups respectively, p=0.0019), but not with T cell mediated rejection Banff scores “i” and “t”. In addition, EndMT markers allowed us to identify ABMR at an early stage (i.e. before any clinical or histological features of ABMR), as well as C4d-negative ABMR. EndMT markers were more specific than capillaritis for the diagnosis and prognosis of ABMR, predicting late (up to 4 years post biopsy) renal graft dysfunction (rho=-0.66, p<0.0001) and proteinuria (rho=0.414, p=0.023). A prolonged cold ischemia time and a history of delayed graft function were the main risk factors associated with the occurence of EndMT markers. In the second independent set of 72 renal graft biopsies, the diagnostic value of EndMT markers for ABMR was confirmed and showed a sensitivity of 85.7% and a specificity of 96.7%. Conclusion: EndMT markers are a sensitive and reliable diagnostic tool for ABMR, and predict late allograft function loss.

LATE RENAL GRAFT REJECTION: PATHOLOGY AND PROGNOSIS

Rejection has always been one of the most important cause of late renal graft dysfunction. Aim of the study was to analyze the prevalence of different clinico-pathological variants of rejection that cause late graft dysfunction, and evaluate their impact on long-term outcome. Materials and methods. This is a retrospective study that analyzed 294 needle core biopsy specimens from 265 renal transplant recipients with late (48,8 ± 46,1 months after transplantation) allograft dysfunction caused by late acute rejection (LAR, n = 193) or chronic rejection (CR, n = 78) or both (n = 23). C4d staining was performed by immunofl uorescence (IF) on frozen sections using a standard protocol. Results. Peritubular capillary C4d deposition was identifi ed in 36% samples with acute rejection and in 62% cases of chronic rejection (including 67% cases of transplant glomerulopathy, and 50% – of isolated chronic vasculopathy). 5-year graft survival for LAR vs CR vs their combination was 47, 13 and 25%, respectively. The outcome of C4d– LAR was (p &lt; 0,01) better than of C4d+ acute rejection: at 60 months graft survival for diffuse C4d+ vs C4d − was 33% vs 53%, respectively. In cases of chronic rejection C4d+ vs C4d– it was not statistically signifi cant (34% vs 36%). Conclusion. In long-term allograft biopsy C4d positivity is more haracteristic for chronic rejection than for acute rejection. Only diffuse C4d staining affects the outcome. C4d– positivity is associated with worse allograft survival in cases of late acute rejection, but not in cases of chronic rejection.