Éva Kemény

The value of electron microscopy in the diagnosis of chronic renal allograft rejection

The main causes of the late dysfunction of renal allografts are chronic rejection and chronic transplant nephropathy. Both are clinicopathologic entities, with a similar clinical presentation, but different histologic appearances. Chronic rejection is characterized by the presence of alloantigen-induced lesions (transplant arteriopathy and transplant glomerulopathy), and chronic transplant nephropathy by nonspecific sclerosing changes. The incidence of transplant arteriopathy and transplant glomerulopathy is relatively low. Electron microscopy (EM) may overcome the limitations in the histologic diagnosis of chronic rejection, because it verifies alloantigen-induced chronic microvasculopathy in the peritubular capillaries (transplant capillaropathy), and identifies transplant glomerulopathy more precisely than does light microscopy. To assess the value of EM in chronic rejection diagnosis, a retrospective search for transplant capillaropathy and transplant glomerulopathy was performed in a consecutive series of 91 biopsies performed ≥6 months after implantation (median: 26 months, range 6–186) and the diagnoses were reclassified on the basis of the ultrastructural findings. The definitions used were: transplant capillaropathy: a peritubular capillary profile with seven or more circumferential basement membrane layers, or at least three profiles with five or six circumferential layers; ultrastructurally verified transplant glomerulopathy: thickening of the capillary wall in at least three loops in consequence of the widening of the subendothelial space by abnormal basement membrane material, and the formation of a new layer(s) of basal lamina; and chronic rejection: the presence of transplant capillaropathy and/or transplant glomerulopathy and/or transplant arteriopathy. Histologically, chronic transplant nephropathy, chronic rejection, chronic cyclosporine nephrotoxicity, glomerulonephritis, acute rejection, “suspicious” for acute rejection, and “others” were diagnosed in 37%, 34%, 21%, 19%, 57%, 30%, and 5% of the specimens, respectively. The results of EM increased the diagnosis of chronic rejection to 69% of the cases, and decreased chronic transplant nephropathy to 15%. The individual incidence of transplant capillaropathy and transplant glomerulopathy was 79% and 57%, respectively, and their cumulative incidence was 92%. Five biopsies exhibited merely transplant arteriopathy. A late dysfunction typically had more than one cause; the most frequent combination was chronic rejection and acute rejection. In conclusion, the EM search for transplant capillaropathy and transplant glomerulopathy doubled the frequency of the diagnosis of chronic rejection. Currently, the evaluation of renal allograft biopsies from recipients with a late dysfunction relies on standard light microscopy. Because light microscopy per se proved to be insensitive in the diagnosis of chronic rejection, incorporation of EM into the evaluation of late dysfunction biopsies is strongly recommended.

Peritubular Capillary Damage in Acute Humoral Rejection: An Ultrastructural Study on Human Renal Allografts

The ultrastructural features of peritubular capillary (PC) damage was studied in 12 kidney allografts with acute humoral rejection (AHR). AHR manifested in diffuse linear PC staining for C4d, and histology consistent with Banff grade III in 7 recipients and Banff grade II in 5. Allografts with acute tubular necrosis served as controls. First biopsies (post‐transplantation day 16.2 ± 2.2): The intra‐capillary exudate comprised monocytes (59%), polymorphonuclears (14%), lymphocytes (12%) and not otherwise specified mononuclears (15%). Three patterns of focal PC endothelial injury were observed: lysis, an increased rate of apoptosis and fragmentation. No correlation was found between the respective damage types and the inflammatory cell types or the Banff grades. Controls revealed endothelial swelling, detachment from basement membrane and fragmentation. Follow‐up biopsies: Monocytes transformed into macrophages intra‐luminally. The reparative changes comprised endothelial cytoplasmic protrusions, binucleated endothelial cells and capillary sprouts. Early transplant capillaropathy and transplant glomerulopathy were noted in 2 recipients. Literature data indicate that lysis is mediated by anti‐HLA alloantibodies; apoptosis, demonstrated first in the present study, may be induced by non‐HLA‐type anti‐endothelial antibodies. Fragmentation is caused by ischemia. Ongoing endothelial injury leads to transplant capillaropathy and transplant glomerulopathy, the characteristic lesions of chronic rejection.

Primer: Histopathology of polyomavirus-associated nephropathy in renal allografts

The BK polyomavirus exhibits tropism for the renal tubular epithelium, where it establishes latent infection. Vigorous immunosuppression of renal allograft recipients can lead to reactivation of the infection and the development of polyomavirus-associated nephropathy (PVAN). Clinically, gradually decreasing renal function, viremia and viruria are observed several months after transplantation; allograft failure occurs in 1–10% of patients. Definitive diagnosis requires an allograft biopsy. Histologically, viral replication results in tubular epithelial cell enlargement, karyomegaly and nuclear inclusion bodies. The cytopathic changes are often associated with lysis of tubular epithelial cells, denudation of the basement membrane and an interstitial inflammatory response. The involvement is multifocal; distal nephron segments are more severely affected than proximal segments. Changes observed during light microscopy are suggestive but not pathognomonic for PVAN, and the diagnosis must be confirmed by adjunct studies. Adjunct studies consist of immunohistochemistry on paraffin sections using an antibody to the SV40 large T antigen, or electron microscopy of infected tubular epithelial cells (virions 40 nm in diameter). PVAN manifests in three histologic patterns: pattern A, viral cytopathic changes with no or only minimal inflammation; pattern B, cytopathic and cytolytic lesions with interstitial inflammation; or pattern C, predominantly interstitial fibrosis and tubular atrophy, with variable cytopathic and inflammatory changes. These patterns correlate with clinical outcomes.

CYCLOSPORIN FOR DYSTROPHIC EPIDERMOLYSIS BULLOSA

A 65-year-old woman with epidermolysis bullosa since childhood was first admitted to our clinic in September, 1987. At first we treated the patient with high doses of vitamin E, phenytoin, prednisolone, and erythromycin but without sucess. When we read a report of the use of cyclosporin in a patient with epidermolysis bullosa acquisita, we began treatment with the above drug combination plus cyclosporin 1 mg/kg daily. Soon after the interruption of cyclosporin therapy, the blisters and erosions reappeared again. Cyclosporin was reintroduced and significant improvement was noted one month later

Plasma cell infiltrates in polyomavirus nephropathy

Polyomavirus (PV) associated nephropathy (PVAN) has become an important cause of allograft dysfunction. We studied plasma cells (PCs) – which have not yet been characterized – present in the cellular infiltrate of 20 PVAN cases using immunohistochemistry and morphometry. The results were correlated with morphological, clinical and anti‐BK virus serological findings. PC‐rich cellular infiltrates occurred in 50% of cases (>15% PCs in the cellular infiltrate) and in these IgM producing PCs were commonly seen (70%): IgM PC predominance in 50% of cases and a comparable number of IgM and IgG PCs in 20% of cases. We found a significant correlation not just between the absolute numbers (P < 0.034) and the percentage values of IgM PCs (P < 0.004 in relation to all cells) and the serum IgM‐Ab anti‐BKV activity, but also between the ratio of IgG/IgM PCs and the ratio of serum IgG/IgM‐Ab activities (P < 0.0001). We showed that IgM PC counts in biopsies correlate with titers of circulating anti‐BK virus IgM antibodies. Every case except one was C4d negative in peritubular capillaries (PTC). As IgG PCs characterize PC‐rich rejection cases, we suggest that in the presence of IgM PCs in PC‐rich infiltrate with PTC C4d negativity, a search for possible PVAN infection should be initiated.

Assessment of donor biopsies.

Purpose of reviewTo provide an up-to-date overview about the assessment of donor biopsies and to discuss the current problems and chances of preimplantation biopsies for transplant allocation with a focus on the technical work up and the histological variables scored. Recent findingsPreimplantation biopsy results are the major reason for discarding procured extended donor criteria kidneys in the USA. There is neither a consensus on the work up, nor the reporting of preimplantation donor biopsies, nor the importance of the biopsy findings in the process of allocation. The best available data have been collected in the context of single vs. double kidney transplantation. A clinical risk factor score may help to define kidneys when a preimplantation biopsy is warranted. Punch biopsies using a skin punch device appear to be a reasonable alternative for surgeons fearing needle biopsies. SummaryDonor biopsies are very useful as zero-hour biopsies establishing baseline information for comparison with subsequent transplant biopsies. As none of the histological variables and scores provides perfect prediction, preimplantation biopsy results have to be interpreted in the context of all available donor and recipient information.

Treatment of Subclinical Injuries Detected by Protocol Biopsy Improves the Long-Term Kidney Allograft Function: A Single Center Prospective Randomized Clinical Trial

BACKGROUND The long-term benefit of early treatment of subclinical disorders detected in kidney allografts by protocol biopsy is controversial. We collected 145 protocol biopsies from 113 recipients for comparison with 51 control patients in a single-center, prospective, randomized trial. METHODS Ultrasound-guided biopsies were performed in recipients with stable renal function. Samples were taken at 3 (n=66) and/or 12 months (n=79) after transplantation. The biopsies were evaluated according to the Banff scheme, and patients were treated based on the diagnosis. Changes in glomerular filtration rate (GFR) were compared with 51 patients who were randomized as a control group. RESULTS The findings on 38 samples (29%) were considered to be normal. Based on the pathology findings, such as subclinical acute rejection (n=23), calcineurin inhibitor toxicity (n=28), chronic rejection (n=6), and other specific pathologies (n=23), including polyoma virus nephropathy (n=2), induced treatment among 82 recipients (57%). Significantly better graft function was observed at 3-year follow-up among the biopsy group, compared with controls: GFR = 46.0 ± 13.8 vs 35 ± 15 mL/min (P=.002). The 5-year graft survival was significantly higher in the biopsy (81%) than in the control (55.6%) group (P=.0012). CONCLUSION Early detection and treatment of subclinical pathologies improved graft function and long-term survival. Protocol biopsies were a valuable tool for posttransplantation management.

Side effects of the calcineurin inhibitor, such as new-onset diabetes after kidney transplantation

New-onset diabetes after transplantation (NODAT) is one of the frequent complications following kidney transplantation. Patients were randomized to receive cyclosporine A- or tacrolimus-based immunosuppression. Fasting and oral glucose tolerance tests were performed, and the patients were assigned to one of the following three groups based on the results: normal, impaired fasting glucose/impaired glucose tolerance (IFG/IGT), or NODAT. NODAT developed in 14% of patients receiving cyclosporine A-based immunosuppression and in 26% of patients taking tacrolimus (p = 0.0002). Albumin levels were similar, but uric acid level (p = 0.002) and the age of the recipient (p = 0.003) were significantly different comparing the diabetic and the normal groups. Evaluation of tissue samples revealed that acute cellular rejection (ACR) and interstitial fibrosis/tubular atrophy (IF/TA) were significantly different in the NODAT group. The pathological effect of new-onset diabetes after kidney transplantation can be detected in the morphology of the renal allograft earlier, before the development of any sign of functional impairment.

Banff-score-változások a marginális donorokból származó veséknél

Absztrakt Bevezetes: A transzplantacios varolistan szereplő betegek szamanak folyamatos novekedese miatt az idealis donor kriteriumainak kibővitesere van szukseg. Celkitűzes: A szerzők azt a kerdest vizsgaltak, hogy vesetranszplantacio utan egy es ot evvel van-e szignifikans kulonbseg a vesefunkcioban es/vagy -morfologiaban a marginalis es idealis donorbol szarmazo vesevel rendelkező betegek kozott. Modszer: A vizsgalatba 275 beteget vontak be, kozuluk 97 marginalis es 178 „idealis” veserecipiens volt. A marginalis es az „idealis” veserecipiensek koreben vizsgaltak a donoralapadatokat es elemeztek a transzplantacio utan egy es ot evvel a funkcionalis es hisztopatologiai valtozasokat. Eredmenyek: A graft funkciojat vizsgalva a transzplantacio utan egy evvel nem volt kulonbseg a ket betegcsoport kozott, mig az otodik evben a szerumkreatinin szignifikansan magasabb (p = 0,0001) es a glomerularis filtracios rata szignifikansan alacsonyabb volt (p = 0,003) a marginalis veserecipiensek csoportjaban az idealis v...

T-sejt-mediált rejectio gyakorisága vesetranszplantáció után, újonnan kialakult diabetes mellitusban

Absztrakt Bevezetes: A vesetranszplantacio utan az egyik leggyakoribb szovődmeny az ujonnan kialakult diabetes mellitus. Celkitűzes: A szerzők celja volt, hogy a vesetranszplantacio utan felmerjek a cyclosporin-A-t (n = 95) es tacrolimust (n = 102) szedők koreben az ujonnan kialakult diabetes mellitus előfordulasi gyakorisagat, es ennek hatasat a T-sejt-medialt rejectio gyakorisagara. Modszer: Transzplantacio utan egy evvel vizsgaltak az eletkort, a laboratoriumi eredmenyeket, a vesefunkciot es morfologiat. A szovettani mintakat az 1997-es Banff-klasszifikacio 2007-es modositasa alapjan ertekeltek. Eredmenyek: A cyclosporin-A-alapu immunszuppresszioban reszesultek koreben 12%, a tacrolimust szedőknel 24% volt az ujonnan kialakult diabetes mellitus előfordulasi gyakorisaga (p = 0,002). Az albumin nem, de a hugysavszint (p = 0,002), valamint a recipiens eletkora (p = 0,003) szignifikansan eltert a diabeteses es nem diabeteses betegcsoportok kozott. A vesefunkciot vizsgalva a szerumkreatinin, a becsult glome...