Recurrent Hepatitis C in Liver Allografts

Enhancing the Value of Histopathological Assessment of Allograft Biopsy Monitoring

Traditional histopathological allograft biopsy evaluation provides, within hours, diagnoses, prognostic information, and mechanistic insights into disease processes. However, proponents of an array of alternative monitoring platforms, broadly classified as "invasive" or "noninvasive" depending on whether allograft tissue is needed, question the value proposition of tissue histopathology. The authors explore the pros and cons of current analytical methods relative to the value of traditional and illustrate advancements of next-generation histopathological evaluation of tissue biopsies. We describe the continuing value of traditional histopathological tissue assessment and "next-generation pathology (NGP)," broadly defined as staining/labeling techniques coupled with digital imaging and automated image analysis. Noninvasive imaging and fluid (blood and urine) analyses promote low-risk, global organ assessment, and "molecular" data output, respectively; invasive alternatives promote objective, "mechanistic" insights by creating gene lists with variably increased/decreased expression compared with steady state/baseline. Proponents of alternative approaches contrast their preferred methods with traditional histopathology and: (1) fail to cite the main value of traditional and NGP-retention of spatial and inferred temporal context available for innumerable objective analyses and (2) belie an unfamiliarity with the impact of advances in imaging and software-guided analytics on emerging histopathology practices. Illustrative NGP examples demonstrate the value of multidimensional data that preserve tissue-based spatial and temporal contexts. We outline a path forward for clinical NGP implementation where "software-assisted sign-out" will enable pathologists to conduct objective analyses that can be incorporated into their final reports and improve patient care.

Incidence of Post-Liver Transplant Hepatic Dysfunction After Sustained Virologic Response Following Direct-Acting Anti-Hepatitis C Therapy

OBJECTIVES

Newly developed, direct-acting antiviral therapy is effective in over 90% of cases to eradicate hepatitis C virus infection. Direct-acting antiviral therapy is also effective in liver transplant recipients with recurrent hepatitis C virus infection. However, hepatic function after sustained virologic response in transplant recipients is unknown. Here, we aimed to uncover the incidence of hepatic dysfunction in this patient group at our center.

MATERIALS AND METHODS

Our study included 40 consecutive (January 2014 to February 2016) and compliant posttransplant recipients who achieved sustained viral response from direct-acting antiviral therapy. Patients were investigated for incidence and causes of hepatic dysfunction.

RESULTS

In our patient group, 4 (10%) experienced hepatic dysfunction with stable baseline immunosuppression, with 2 having drastic increases in alanine aminotransferase at 15 and 32 weeks after direct-acting antiviral therapy. Biopsies showed hepatitis, and both patients were treated with hydrocortisone, which increased their baseline immunosuppression. The 3rd patient had an increase in bilirubin at 21 weeks posttherapy, with biopsy showing macrovascular steatosis. The 4th patient had a rapid increase in bilirubin at 7 weeks after direct-acting antiviral therapy, with biopsy showing significant duct loss.

CONCLUSIONS

During the study period, 10% of patients experienced hepatic dysfunction after sustained viral response. Presumed causative factors included partial immune reconstitution and nonalcoholic fatty liver disease.

Acute cellular rejection versus recurrent hepatitis C after liver transplantation: Clinical and pathological features driving a rational diagnostic approach

AIM

The aim of our study was develop and validate an algorithm system based on morphological features for finding the differences between recurrent hepatitis C virus (HCV) and acute cellular rejection (ACR) in liver biopsies of HCV-transplanted patients.

METHODS

Two hundred and eighty-eight liver biopsies were analyzed from 121 patients transplanted for HCV. A diagnostic consensus was reached between clinicians and pathologists in 214 biopsies for the diagnosis of recurrent HCV or ACR. A random sample of 114 liver biopsies (derivation cohort) was taken to generate the diagnostic tree and was subsequently evaluated using the validation cohort in 100 liver biopsies by recursive partitioning analysis of morphological variables and time since transplantation.

RESULTS

The presence of endotheliitis together with a time of less than 6 weeks since LT definitely excluded recurrent HCV. After obtaining the regression tree, diagnostic accuracy was 96% and 93% in the derivation and validation cohort, respectively. Both cases surpassed the pathologist's original diagnosis, which had a diagnostic accuracy of 91% (P < 0.05, for both comparisons).

CONCLUSION

A recursive partitioning analysis of the morphological features in liver biopsies from HCV-transplanted patients may be useful for easily distinguishing between recurrent HCV and ACR.

Impact of alloimmune T cell responses on hepatitis C virus replication in liver transplant recipients

We investigated the influence of alloimmune T cell responses on hepatitis C virus (HCV) replication in HCV-infected patients after liver transplantation (LT). To monitor the immune-status in 27 HCV-infected LT recipients, we routinely performed mixed lymphocyte reaction (MLR) assays within 4 weeks after LT. HCV RNA titers in most patients fluctuated in inverse proportion to the stimulation index (SI) of anti-donor reactive T cells early after LT. Two weeks after LT, recipients with high HCV RNA titers (>1000 KIU/mL) displayed a significantly lower SI for anti-donor reactive T cells than recipients with low HCV RNA titers did (<1000 KIU/mL). An in vitro transwell assay mimicking the anatomical features of the interaction between HCV-infected hepatocytes and alloreactive T cells in allograft livers demonstrated that interferon (IFN)-γ was necessary to suppress HCV replication. This study proves the significant impact of alloimmune T cell responses on HCV replication in HCV-infected LT recipients.

"Plasma cell hepatitis" in liver allografts: identification and characterization of an IgG4-rich cohort

Plasma cell hepatitis (PCH), also known as "de novo autoimmune" hepatitis, is an increasingly recognized, but suboptimally named and poorly understood, category of late allograft dysfunction strongly resembling autoimmune hepatitis (AIH): They share plasma-cell-rich necro-inflammatory activity on biopsy, autoantibodies and steroid responsiveness, but overlap with rejection is problematic. A retrospective study of clinical, serological, histopathological and IgG4 immunohistological features of PCH (n = 20) in liver allograft recipients, native liver AIH (n = 19) and plasma-cell-rich renal allograft rejection (n = 20) showed: (1) high frequency (44%) of HLA-DR15; (2) less female predominance (p = 0.03) and (3) n = 9/20 PCH recipients showed >25 IgG4+ plasma cells/high-power field (IgG4+ PCH) versus AIH (n = 1/19, p = 0.008) or plasma-cell-rich kidney rejection (n = 2/20, p = 0.03). The IgG4+ PCH (n = 9) subgroup showed lower alanine transaminase (ALT) (p < 0.01) and aspartate transaminase (AST) (p < 0.05) at index biopsy but (a) higher plasma cell number/percentage, (b) more aggressive-appearing portal/periportal and perivenular necro-inflammatory activity and (c) more severe portal/periportal fibrosis than IgG4- PCH (n = 11). Significant demographic, histopathologic and plasma cell phenotype differences between PCH and AIH suggest distinct pathogenic mechanisms for at least the IgG4+ PCH subgroup likely representing an overlap between allo- and auto-immunity. IgG4+ PCH was associated with fibrosis, but also highly responsive to increased immunosuppression.

Development of a robust protocol for gene expression analysis using formalin-fixed, paraffin-embedded liver transplant biopsy specimens

Liver transplant biopsies are routinely archived following formalin fixation and paraffin embedding and may provide an additional source of diagnostic information following transcriptomic biomarker analysis. This study was designed to compare gene transcription between resting and stressed biliary cells in culture, these cells after fixation and embedding and archival liver transplant biopsy tissue. The transcription of p21/WAF1 and transforming growth factor (TGF)-β1 showed similar changes in the fresh and embedded liver cells. However, the expression of TGF-β2 was markedly different between the fresh and embedded samples, suggesting that fixation can produce sequence-specific artefacts. Sufficient quantities of pure RNA were recovered from all the liver transplant biopsies to allow complementary DNA production. Measurement of the transcription of all three genes showed variability between the cases. Although the results for individual transcripts should be interpreted with care, these data do suggest the feasibility of performing a larger biomarker discovery studies using archival tissue.

Liver Transplant Pathology: Review of Challenging Diagnostic Situations

Histopathologic assessment of allograft liver biopsies has an important role in managing patients who have undergone liver transplantation. In this review, several topics are discussed that create diagnostic problems in transplant pathology, with emphasis on pathologic features and differential diagnosis. The topics discussed are acute cellular rejection, late acute rejection (centrizonal/parenchymal rejection), chronic rejection, plasma cell hepatitis, idiopathic posttransplant chronic hepatitis, fibrosing cholestatic hepatitis, selected viral infections (cytomegalovirus, Epstein-Barr virus, and hepatitis E), and acute antibody-mediated rejection.

Recurrent diseases following liver transplantation: current concepts

PURPOSE OF REVIEW

Liver transplantation is the treatment of choice for patients with chronic end-stage liver disease. The posttransplant setting is complex, and an improved long-term graft and patient survival adds to the complexity. There are often multiple causes of graft dysfunction and the associated morbidity and disorder are varied. This review focuses on the current concepts of several recurrent diseases, emphasizing the interpretation of the posttransplant liver biopsies in long-term survivors as challenging and clinically more relevant then ever. It confirms the importance and the necessity of clinico-pathologic correlation in the posttransplant setting.

RECENT FINDINGS

The long-term graft and patient survival following liver transplantation has improved significantly over the past decade. The spectrum of histopathologic patterns seen in liver biopsies and our understanding of them have evolved and expanded considerably, so much so, that both pathologists and clinicians alike now recognize new and emerging disease patterns not previously encountered in the nontransplant setting.

SUMMARY

Typical histopathologic features are usually easily identified and interpreted in liver biopsies. There are, however, a number of atypical histopathologic patterns, especially in the setting of recurrent diseases, often modified by immunosuppression, or altered by other immune-mediated processes, autoimmunity, or hepatotoxicity. Several conditions and entities, especially in the late posttransplant setting, including atypical allograft rejection, idiopathic posttransplant hepatitis, the spectrum of changes seen in recurrent hepatitis C, nodular regenerative hyperplasia, and de-novo disease occurrence, to name a few, have all been recognized in the past several years.

Immunosuppression induction with rabbit anti-thymocyte globulin with or without rituximab in 1000 liver transplant patients with long-term follow-up

Rabbit anti-thymocyte globulin (rATG)-based immunosuppression induction is being increasingly used in liver transplantation (LT) in conjunction with steroid-free protocols to delay the initiation of calcineurin inhibitors. This study reports a single-center comparison of transplant outcomes and complications in 3 immunosuppression eras. Data were obtained retrospectively from a center research database, and the analysis included LT patients from 2001 to 2008. The immunosuppression consisted of rATG induction in 3 doses (6 mg/kg in all): (1) the first dose was administered perioperatively [the rabbit anti-thymocyte globulin in the operating room (rATG-OR) era]; (2) the first dose was delayed until 48 hours after transplantation [the rabbit anti-thymocyte globulin after a delay (rATG-D) era]; or (3) the first dose was delayed until 48 hours after transplantation, and a single dose of rituximab was added 72 hours after transplantation [the rabbit anti-thymocyte globulin after a delay plus rituximab (rATG-D-Ritux) era]. The initial maintenance immunosuppression was tacrolimus monotherapy, which was started on postoperative day 2. There were 166 patients (16%) in the rATG-OR era, 259 patients (26%) in the rATG-D era, and 588 patients (58%) in the rATG-D-Ritux era (1013 patients in all). Demographically, the latter eras were characterized by higher recipient and donor ages; greater percentages of liver-kidney transplants, hepatocellular carcinoma (HCC), donation after cardiac death (DCD), and imported organs; and shorter graft ischemia times. There were no significant differences between the 3 immunosuppression groups in unadjusted patient survival 3 and 5 years after transplantation (80% and 75% for the rATG-OR era, 75% and 67% for the rATG-D era, and 79% and 71% for the rATG-D-Ritux era, P = 0.15). The 5-year survival rates for patients with hepatitis C virus (HCV) and HCC were 65% and 68%, respectively. The factors included in the Cox regression model for patient death included the Model for End-Stage Liver Disease score [hazard ratio (HR) = 1.03, P = 0.001], HCV (HR = 1.28, P = 0.04), donor age (HR = 1.01, P = 0.001), recipient age (HR = 1.01, P = 0.05), and DCD (HR = 1.55, P = 0.11). rATG-based induction immunosuppression can be safely used in adult LT recipients with excellent survival and low rejection rates and without increases in immunosuppression-related side effects.

Effectiveness and safety of everolimus in the treatment of autoimmune hepatitis related to anti-hepatitis C virus therapy after liver transplant: three case reports

Treatment of recurrent hepatitis C after liver transplantation is indicated in selected cases. During the combined treatment with pegylated interferon and ribavirin, some patients develop immune-mediated liver dysfunction similar to the previously described "de novo" autoimmune hepatitis. Herein we have presented three liver transplant patients who during or after combined antiviral treatment were diagnosed as autoimmune hepatitis related to interferon based on their clinical, biochemical, and liver histology features. There were two women and one man, of ages 49, 52, and 49 years who were transplanted due to cirrhosis related to hepatitis C virus genotype 1. In two patients, elevated liver enzymes occurred during antiviral therapy and in the third, after the therapy. The diagnosis of autoimmune hepatitis was reached after excluding other possible causes. One patient had a sustained viral response; and two cases were nonresponders. Antinuclear antibodies were present in two subjects and antinuclear antibodies and anti-smooth muscle antibodies in the other case. First-line treatment of autoimmune hepatitis with prednisone and azathioprine stabilized clinical and biochemical parameters'. In order to avoid the long-term use of prednisone, everolimus was introduced in the three patients. Interestingly, hepatitis C did not progress and clinical, biochemical, as well as histological parameters stabilized. In one patient, the liver fibrosis stage as assessed by histology showed improvement. However, one subject experienced repeated cerebral hemorrhage and died. Although this is heterogeneous population with partially known characteristics, with a difficult differential diagnosis, the objectives of preserving liver function and avoiding recurrent progressive hepatitis C seemed to be achieved by adding everolimus. In addition, we totally stopped prednisone therapy. In conclusion, treatment with everolimus in combination with cyclosporine achieved a partial remission in two liver transplan cases of autoimmune hepatitis related to interferon therapy.

Recurrent hepatitis C and acute allograft rejection: clinicopathologic features with emphasis on the differential diagnosis between these entities

Chronic hepatitis C virus infection is the leading etiology for liver transplantation in the United States. Recurrent hepatitis C occurs nearly universally in these patients and represents a serious posttransplantation complication. Despite the detailed characterization of the histologic features of both recurrent hepatitis C and acute cellular rejection (ACR) over the last decades, the pathologic distinction between these 2 conditions remains one of the greatest diagnostic challenges in liver pathology. An accurate diagnosis, nevertheless, plays an essential role in patient management, as different therapeutic strategies are used for these conditions. In this review, the clinicopathologic features of posttransplantation recurrent hepatitis C and ACR are discussed, with emphasis on distinguishing histopathologic features, morphologic variants, ancillary techniques, and diagnostic pitfalls.

What is the long-term outcome of the liver allograft?

With improved long-term survival following liver transplantation (LT), issues relating to the assessment of the liver allograft in long-term survivors are becoming increasingly relevant. Histological abnormalities are commonly present in late post-transplant biopsies, including protocol biopsies from patients who appear to be well with good graft function. Recurrent disease is the commonest recognised cause of abnormal graft histology, but may be modified by the effects of immunosuppression or interactions with other graft complications, resulting in complex or atypical changes. Other abnormalities seen in late post-transplant biopsies include rejection (which often has different appearances to those seen in the post-transplant period), de novo disease, "idiopathic" post-transplant hepatitis (IPTH) and nodular regenerative hyperplasia. In many cases graft dysfunction has more than one cause and liver biopsy may help to identify the predominant cause of graft damage. Problems exist with the terminology used to describe less well understood patterns of graft injury, but there is emerging evidence to suggest that late rejection, de novo autoimmune hepatitis and IPTH may all be part of an overlapping spectrum of immune-mediated injury occurring in the late post-transplant liver allograft. Careful clinico-pathological correlation is very important and the wording of the biopsy report should take into account therapeutic implications, particularly whether changes in immunosuppression may be indicated. This article will provide an overview of the main histological changes occurring in long-term survivors post-LT, focusing on areas where the assessment of late post-transplant biopsies is most relevant clinically.

Clinicopathological features of hepatitis C virus disease after living donor liver transplantation: relationship with in situ hybridisation data

AIMS

Recurrent hepatitis is a significant complication after liver transplantation for hepatitis C virus (HCV) disease. To evaluate responsiveness to treatment of HCV disease after liver transplantation, in situ hybridisation (ISH) was employed.

METHODS

Sense and anti-sense probes for HCV were synthesised, and ISH studies were performed on 19 liver biopsy specimens from 19 recipients who had undergone living donor liver transplantation for HCV disease. ISH positive cells and total hepatocytes were counted, and the percentage of positive cells was calculated. Other clinical findings were compared retrospectively with the ISH results.

RESULTS

The subjects were divided into three groups: recurrent HCV hepatitis (RHC, n = 11), acute cellular rejection (ACR, n = 5), and recurrent HCV hepatitis with ACR (MIX, n = 3). The percentage of ISH positive cells was almost the same degree (10-20%) in the three groups. The RHC group was subdivided into two sets of patients in whom serum HCV titres decreased (group D, n = 7) or did not decrease (group ND, n = 3) after 1 month of IFN therapy. The percentage of ISH positive cells in group D was significantly lower than that in group ND (p < 0.05)

CONCLUSIONS

ISH for the recipients with HCV may be useful for predicting the response to interferon therapy.

Molecular pathways differentiate hepatitis C virus (HCV) recurrence from acute cellular rejection in HCV liver recipients

Acute cellular rejection (ACR) and hepatitis C virus (HCV) recurrence (HCVrec) are common complications after liver transplantation (LT) in HCV patients, who share common clinical and histological features, making a differential diagnosis difficult. Fifty-three liver allograft samples from unique HCV LT recipients were studied using microarrays, including a training set (n = 32) and a validation set (n = 19). Two no-HCV-ACR samples from LT recipients were also included. Probe set intensity values were obtained using the robust multiarray average method (RMA) method. Analysis of variance identified statistically differentially expressed genes (P ≤ 0.005). The limma package was used to fit the mixed-effects models using a restricted maximum likelihood procedure. The last absolute shrinkage and selection operator (LASSO) model was fit with HCVrec versus ACR as the dependent variable predicted. N-fold cross-validation was performed to provide an unbiased estimate of generalization error. A total of 179 probe sets were differentially expressed among groups, with 71 exclusive genes between HCVrec and HCV-ACR. No differences were found within ACR group (HCV-ACR vs. no-HCV-ACR). Supervised clustering analysis displayed two clearly independent groups, and no-HCV-ACR clustered within HCV-ACR. HCVrec-related genes were associated with a cytotoxic T-cell profile, and HCV-ACR-related genes were associated with the inflammatory response. The best-fitting LASSO model classifier accuracy, including 15 genes, has an accuracy of 100% in the training set. N-fold cross-validation accuracy was 78.1%, and sensitivity, specificity and positive and negative predictive values were 50.0%, 90.9%, 71.4% and 80.0%, respectively. Arginase type II (ARG2), ethylmalonic encephalopathy 1 (ETHE1), transmembrane protein 176A (TMEM176A) and TMEM176B genes were significantly confirmed in the validation set. A molecular signature capable of distinguishing HCVrec and ACR in HCV LT recipients was identified and validated.

Measurement of CD4+ T-cell function in predicting allograft rejection and recurrent hepatitis C after liver transplantation

Recurrence of hepatitis C virus (HCV) can be difficult to distinguish from acute cellular rejection (ACR) following liver transplantation. The Cylex Immune Function Assay (ImmuKnow) provides objective measure of recipient's immune function. The goal is to assess the ability of this assay to distinguish these similar conditions. A retrospective review was performed in 54 recipients with HCV. ImmuKnow assays were measured with allograft biopsies. Levels of adenosine triphosphate (ATP) release from CD4+ T cells (ng/mL) were compared with the following biopsy result classifications: 365 ± 130 with ACR (n = 11), 152 ± 100 with recurrent HCV (n = 26), 240 ± 71 with normal biopsies (n = 12), and 157 ± 130 with overlapping features of ACR and recurrent HCV (n = 5). Recipients with recurrent HCV had lower immune response than those with ACR (p < 0.0001).Using a cutoff level of 220, the sensitivity and specificity for distinguishing two conditions were 88.5% and 90.9%, respectively. When recipients with overlapping features had low immune response, three of four recipients' subsequent biopsies showed recurrent HCV. In conclusion, the ImmuKnow assay can be a sensitive and specific additional test for distinguishing recurrent HCV from ACR and may be useful for predicting which recipients may be most vulnerable to recurrent HCV.

Current views on rejection pathology in liver transplantation

Histological assessments continue to play an important role in the diagnosis and management of liver allograft rejection. The changes occurring in acute and chronic rejection are well recognized and liver biopsy remains the 'gold standard' for diagnosing these two conditions. Recent interest has focused on the diagnosis of late cellular rejection, which may have different histological appearances to early acute rejection and instead has features that overlap with so-called 'de novo autoimmune hepatitis' and 'idiopathic post-transplant chronic hepatitis'. There is increasing evidence to suggest that 'central perivenulitis' may be an important manifestation of late rejection, although other causes of centrilobular necro-inflammation need to be considered in the differential diagnosis. There are also important areas of overlap between rejection and recurrent hepatitis C infection and the distinction between these two conditions continues to be a problem in the assessment of liver allograft biopsies. Studies using immunohistochemical staining for C4d as a marker for antibody-mediated damage have found evidence of C4d deposition in liver allograft rejection, but the functional significance of these observations is currently uncertain. This review will focus on these difficult and controversial areas in the pathology of rejection, documenting what is currently known and identifying areas where further clarification is required.

ELISA-based detection of C4d after liver transplantation--a helpful tool for differential diagnosis between acute rejection and HCV-recurrence?

Hepatitis-C is the most common indication for liver transplantation. Recurrence of HCV is universal leading to graft failure in up to 40% of all patients. The differentiation between acute rejection and recurrent hepatitis-C is crucial as rejection treatments are likely to aggravate HCV-recurrence. Histological examination of liver biopsy remains the gold standard for diagnosis of acute rejection but has failed in the past to distinguish between acute rejection and recurrent hepatitis-C. In a retrospective study we have recently reported that C4d as a marker of the activated complement cascade is detectable in a hepatic specimen in acute rejection after liver transplantation and may serve as a valuable tool in differential diagnosis between ACR and HCV-recurrence. We performed a prospective analysis by ELISA measurement of C4d concentration in cryo-preserved liver biopsies of LTX patients who had either experienced acute rejection, hepatitis-C recurrence or displayed no pathological alterations (controls). Opposed to our immunohistologically based findings in paraffinized tissue we were unable to detect significant differences of C4d concentration in ELISA of cryo-preserved liver tissue. Consequently the role and potential value of C4d as a diagnostic marker may not be determined using ELISA-based tissue evaluation.

Evolution of hepatitis C virus in liver allografts

1. Hepatitis C virus (HCV) RNA+ liver allograft recipients invariably reinfect the liver allograft within hours after transplantation, and the majority (>70%) develop chronic hepatitis. The rate at which these patients experience progression to cirrhosis and the overall percentage are significantly increased in comparison with HCV infection in the nontransplant setting. 2. Core needle biopsy evaluation is used to establish the diagnosis of recurrent HCV, which can be difficult to distinguish from acute cellular rejection and other causes of allograft dysfunction. In the vast majority of cases, however, distinguishing recurrent HCV from other posttransplant syndromes is reliably achieved by a careful examination of hematoxylin and eosin-stained sections and correlation with clinical and serological data. 3. Recurrent HCV often coexists with other causes of liver allograft dysfunction, and the determination of the most important cause of injury and whether other causes of injury are present is important. Included are residual changes of preservation/reperfusion injury, biliary sludging/structuring, acute cellular and chronic rejection, and autoimmune hepatitis. 4. The complex interplay between immunosuppression management, viral replication, and the recipient immune system results in distinct patterns of recurrent chronic HCV in the liver allograft: (1) conventional or usual acute and chronic HCV, which resembles that seen in the general population with HCV; (2) fibrosing cholestatic hepatitis; and (3) plasma cell-rich HCV, which might represent a variant of, or overlap with, autoimmune hepatitis and rejection. 5. The variable but usually hastened histopathological progression toward cirrhosis in HCV+ allografts is similar to that seen in the nontransplant setting, but in allografts, the overall severity of lymphocytic inflammation is less, and ductular reactions, stellate cell activation, and subsinusoidal fibrosis are accentuated. Hepatic stressors and causes of an impaired ability of hepatocytes to replicate include persistently high levels of viral replication, HCV-specific CD4+ T responses, advanced donor age, high levels or rapid withdrawal of immunosuppression, and coexistent liver damage from preservation/reperfusion injury, biliary structuring, or coexistent cytomegalovirus or herpes 6 viral infection. 6. Immunological effector mechanisms involved in the rejection and control of HCV replication/HCV elimination show significant overlap. Patients with very high levels of HCV RNA rarely show significant clinically significant acute or chronic rejection, whereas their occurrence is frequently associated with very low levels or clearance of HCV RNA. Studying the evolution from recurrent HCV to acute rejection in patients treated with interferon and/or weaned from immunosuppression might provide valuable insights into the relationship between these 2 processes as well as liver allograft acceptance.

Immunohistochemical staining of liver grafts with a monoclonal antibody against HCV-Envelope 2 for recurrent hepatitis C after living donor liver transplantation

AIM

We evaluated the expression of hepatitis C virus (HCV) antigen on liver grafts by immunohistochemical staining (IHS) using IG222 monoclonal antibody (mAb) against HCV-envelope 2 (E2).

METHODS

The study material was 84 liver biopsy specimens obtained from 28 patients who underwent living donor liver transplantation (LDLT) for HCV infection. The biopsy samples were examined histopathologically, and by IHS using IG222 mAb against HCV-E2. Serum HCV-RNA level was measured in all patients. The IHS grades were compared among the three groups classified according to the time elapsed from LDLT (at 1-30, 31-179 and > or =180 days post-LDLT) and among four post-transplant conditions, including acute cellular rejection (ACR).

RESULTS

Immunoreactivity to IG222 was detected in 78.6% of the specimens obtained during the first month after LDLT, and there were no significant differences on the IHS grades between the three groups classified according to the time elapsed from LDLT. The IHS grades were significantly stronger in definite recurrent HCV (n = 12) and probable recurrent HCV (n = 7) than in definite ACR (n = 7) and other complications (n = 8). There were no significant differences in serum HCV-RNA levels among the four post-transplant conditions. There was no significant correlation between the IHS grades using IG222 mAb and serum HCV-RNA levels when data of 84 liver biopsy specimens were analyzed.

CONCLUSIONS

Constant HCV-E2 expression was observed in liver biopsy specimens obtained 1 month or longer. The strong HCV-E2 expression on liver grafts were associated with recurrent hepatitis C after LDLT, but the serum HCV-RNA levels were not.

Serum autoantibodies against cytochrome P450 2E1 (CYP2E1) predict severity of necroinflammation of recurrent hepatitis C

We previously reported that autoantibodies against cytochrome P4502E1 (CYP2E1) are frequent in patients with chronic hepatitis C. As autoimmune reactions are increasingly detected after orthotopic liver transplantation (OLT), this study investigates prevalence and significance of anti-CYP2E1 autoantibodies in 46 patients with post-OLT recurrent hepatitis C. IgG against recombinant human CYP2E1 above the control threshold was detected in 19 out 46 (41%) sera collected immediately before OLT and in 15 out 46 (33%) sera collected at the time of the 12 months follow-up liver biopsy. Although anti-CYP2E1 reactivity was not modified by OLT, the patients with persistently elevated anti-CYP2E1 IgG (n = 12; 26%) showed significantly higher prevalence of recurrent hepatitis with severe necroinflammation and fibrosis than those persistently negative or positive only either before or after OLT. Moreover, the probability of developing severe necroinflammation was significantly higher in persistently anti-CYP2E1-positive subjects. Multivariate regression and Cox analysis confirmed that the persistence of anti-CYP2E1 IgG, together with a history of acute cellular rejection and donor age >50 years, was an independent risk factor for developing recurrent hepatitis C with severe necroinflammation. We propose that autoimmune reactions involving CYP2E1 might contribute to hepatic damage in a subgroup of transplanted patients with recurrent hepatitis C.

Seeking beyond rejection: an update on the differential diagnosis and a practical approach to liver allograft biopsy interpretation

Pathologic evaluation of liver allograft biopsies plays an integral role in the management of patients after liver transplantation. This review summarizes the clinical context and classical histology of different types of allograft rejection and also the common entities that enter the differential diagnosis of allograft rejection, and provides practical approaches to liver allograft biopsy interpretation. In addition, some of the new developments in the field of liver transplant pathology are updated. The purpose of this review is to provide guidance for pathologists interpreting liver allograft biopsies, particularly those interested in developing expertise in the field of liver transplant pathology.

Prospective study of natural killer cell phenotype in recurrent hepatitis C virus infection following liver transplantation

BACKGROUND/AIMS

Graft re-infection invariably occurs after liver transplantation (OLT) for chronic hepatitis C and disease progression is unpredictable. We prospectively examined peripheral blood mononuclear cells (PBMC) subsets and natural killer (NK) cell receptors (NKRs) in patients with recurrent hepatitis C post-OLT.

METHODS

PBMC were obtained at baseline and at different time points after OLT. NKRs were identified using monoclonal antibodies by flow cytometry.

RESULTS

The proportions of NK, natural T (NT), total and gammadelta T cells were significantly reduced (p<0.01) 7 days post-transplant, probably as a result of graft repopulation. NKG2D+ NK cells were significantly higher compared with healthy controls (p<0.01), declined post-OLT and subsequently returned to baseline values. This, together with a progressive increase in the proportion of CD94/NKG2C+ NK cells over time (p< or = 0.01), appeared to be related to hepatitis C recurrence. There was a statistically significant correlation between expression of the natural cytotoxicity receptors (NCRs) and ALT (p<0.05), supporting the hypothesis that NK cells participate in the necroinflammatory process.

CONCLUSIONS

The data are compatible with homing of immune cells to the liver allograft after surgery, most of which return to pre-OLT levels. HCV recurrence may cause variations in selected NKRs expression akin to other viral infections.

Using an immune functional assay to differentiate acute cellular rejection from recurrent hepatitis C in liver transplant patients

In transplant recipients transplanted for hepatitis C, presentation of abnormal transaminases can herald the presentation of recurrent hepatitis C, cellular rejection, or both. Given the sometimes ambiguous histology with these 2 entities, the ability to distinguish them is of great importance because misinterpretation can potentially affect graft survival. We used an immune functional assay to help assess the etiology of abnormal liver function test results in liver transplant recipients. Blood samples for the immune functional assay were taken from 42 recipients prospectively at various times post-transplant and compared with clinical and histologic findings. In patients whose liver biopsy showed evidence of cellular rejection, the immune response was noted to be very high, whereas in those with active recurrence of hepatitis C, the immune response was found to be very low. This finding was found to be statistically significant (P < 0.0001). In those patients in whom there was no predominant histologic features suggesting 1 entity over the other, the immune response was higher than in those with aggressive hepatitis C but lower than in those with cellular rejection. In conclusion, these data show the potential utility of the ImmuKnow assay as a means of distinguishing hepatitis C from cellular rejection and its potential usefulness as a marker for outlining the progression of hepatitis C.

Long-term outcome of human leukocyte antigen mismatching in liver transplantation: results of the National Institute of Diabetes and Digestive and Kidney Diseases Liver Transplantation Database

A perfect or nearly perfect human leukocyte antigen (HLA) match has been associated with better immediate and long-term survival of diseased donor kidney transplants. However, the effect of HLA matching for hepatic allografts remains poorly defined. Using data from the National Institutes of Diabetes and Digestive and Kidney Diseases Liver Transplantation Database, we investigated the association between HLA mismatches and hepatic allograft survival, disease recurrence, and immunosuppression interactions. A, B, and DR loci were used to calculate total mismatch scores of 0 (no mismatches in any loci) to 6 (mismatches in all loci). Seven hundred ninety-nine adults (male, 55%; female, 45%) underwent 883 liver transplants. The 10-year graft survival according to total mismatch score was as follows: 0-2, 60%; 3-4, 54%; and 5-6, 57%. There was a negative effect of mismatching at the A locus on patient survival, with shorter survival for patients with 1 or 2 mismatches compared with 0 mismatches [P = 0.05, hazard ratio (HR) = 1.6]. Patients on tacrolimus with 1 or 2 mismatches at B or DR loci appeared to have increased rates of patient and graft survival compared to patients with 0 mismatches, with the appearance of a protective effect of tacrolimus (HR = 0.67). The effect of HLA mismatching was more pronounced on certain disease recurrences. DR-locus mismatch increased recurrence of autoimmune hepatitis (P = 0.01, HR = 4.2) and primary biliary cirrhosis (P = 0.04, HR = 2). Mismatch in the A locus was associated with more recurrence of hepatitis C virus (P = 0.01, HR = 1.6) and primary sclerosing cholangitis (P = 0.03, HR = 2.9).

CONCLUSION

Mismatching at the A locus decreases patient survival in liver transplant recipients, and mismatching at the DR and A loci affects recurrence of autoimmune liver diseases and hepatitis C, respectively.

The use of molecular assays in the management of viral hepatitis

Molecular assays are instrumental in the clinical management of viral hepatitis. During the past years, a wide variety of molecular assays have been developed and implemented. This considerably improved the understanding of the natural history and pathogenesis of Hepatitis B virus (HBV), Hepatitis C virus (HCV) or Hepatitis delta virus (HDV) hepatitis, but also caused uncertainties in the selection of the most appropriate assays for clinical requirements. Indeed, a rational choice and application of these assays requires adequate knowledge of the performance of the single test. Moreover, the choice of the most accurate assay for patients' needs and physicians' objectives, needs to be oriented to specific contexts, such as diagnosis, management or treatment. In the past, a hurdle in the routine use of assays for hepatitis viruses nucleic acid quantification was represented by the availability of only "home brew" methods which lacked standardization. Major improvement in addressing the use of molecular assays for viral hepatitis has been derived from recent standardization procedures that allowed a comparison between different tests after results were given as International Units. In addition, it should be reminded that, before getting into the market, molecular assays should be approved by European regulation authorities and validated using internationally recognized standards. A subsequent clinical validation should address the diagnostic accuracy of the assay. These proceedings have the aim of identifying which molecular tests, among those currently available, meet clinical requirements for each specific application.

Controversies in liver transplantation for hepatitis C

Hepatitis C is one of the most common indications for liver transplantation in the United States, accounting for approximately 40%-45% of all liver transplants. Unfortunately, recurrent disease is universal in patients who are viremic before transplantation. This can lead to cirrhosis in at least 25% of patients 5 years after liver transplantation, and recurrent hepatitis C is now emerging as an important but occasionally contentious indication for retransplantation. Several attempts have been undertaken to identify patients at high risk for severe recurrent disease who may benefit from treatment, but unfortunately antiviral therapy frequently is ineffective and often is associated with numerous side effects. Although we have made significant strides in understanding the natural history of this disease in nontransplant patients, this does not hold true for the transplant population in which several uncertainties covering virtually the entire spectrum of liver transplantation persist. Despite these concerns, on a more practical level, it is usually only in the postoperative setting that clinicians truly can assess the impact of their interventions on the natural history of recurrent hepatitis C, for example, by adjusting immunosuppression or prescribing antiviral therapy. Preoperative and perioperative (including donor) factors often are outside the control of hepatologists and transplant surgeons. This review is not an inclusive review of the literature but summarizes what we believe are the more controversial topics of this disease.

Tissue hepatitis C virus RNA quantification and protein expression help identify early hepatitis C virus recurrence after liver transplantation

We compared tissue hepatitis C virus (HCV) RNA polymerase chain reaction quantification and HCV immunohistochemistry (IHC) to histology in biopsy tissues in order to differentiate between acute rejection and HCV hepatitis recurrence early after orthotopic liver transplantation (OLT). We analyzed the first biopsy performed because of alteration of serum aminotransferases in 65 consecutive OLT patients with HCV genotype 1b. In the histological analysis, we quantified the portal tracts, Councilman bodies, Councilman body/portal tract (CP) ratio, steatosis, and Knodell and Ishak scores. The 52 patients (80%) with histological HCV recurrence [recurrence-positive (Rec+)] were separated from the 6 (9%) with acute rejection and the 7 (11%) with undetermined pathological features [recurrence-negative (Rec-)]. HCV RNA strongly correlated with HCV IHC, regardless of the histological diagnosis (P < 0.001). Both HCV RNA and HCV IHC were significantly associated with CP ratio (P = 0.041 and P = 0.008). No statistical correlation was found between HCV RNA, HCV IHC, and the other histopathologic features or the hepatitis scores. HCV RNA, HCV IHC, and CP ratio were the only variables able to discriminate between Rec+ and Rec- patients (Mann-Whitney test P < 0.001, P < 0.001, P = 0.014). In conclusion, a combined evaluation of histology, tissue HCV RNA, and HCV IHC significantly discriminated between OLT patients with or without HCV recurrence.

[Clinical outcome after living donor liver transplantation in patients with hepatitis C virus-associated cirrhosis]

BACKGROUND AND AIMS

Hepatitis C virus (HCV)-associated cirrhosis is an increasingly frequent indication for liver transplantation (LT). However, HCV recurrence is universal and this immediately occurs following LT, which endangers both the graft and patient survival. We investigated the frequency of posttransplant recurrence of HCV infection and the patient-graft survival, and we analyzed the responses to ribavirin and interferon therapy in the patients with recurrent HCV infection after living donor liver transplantation (LDLT).

METHODS

We retrospectively reviewed the clinical outcomes of 39 HCV-associated cirrhosis patients who underwent LDLT at Asan Medical Center between August 1992 and June 2006. In this study, the diagnosis of recurrent HCV was made on the basis of increased transaminases and serum HCV RNA levels greater than 10 million IU/mL because protocol liver biopsy was not performed.

RESULTS

HCV recurrence was seen in 26 of the 39 LDLT patients (66.7%). 86.7% of recurrence occurred within the first postoperative year. Antiviral treatment was used for all patients with recurrence of HCV. None of the 10 patients receiving ribavirin alone and 9 of 16 patients who received combination therapy with pegylated interferon alpha-2a plus ribavirin became HCV RNA negative and they remained persistently negative during the median follow-up of 24.9 months. Our data indicates that there is no significant factor influencing HCV recurrence except for the recipient's age. The 2-year patient survival for the HCV patients with HCC and those patients without HCC were 81.2% and 81.3%, respectively (P=0.85) and the 2-year graft survival rates were 81.2% and 68.2%, respectively (P=0.29). No patient died from HCV recurrence during the follow-up period.

CONCLUSIONS

Combination therapy with ribavirin and interferon appears to improve the outcome of recurrent HCV infected patients after LDLT.

Histology of symptomatic acute hepatitis C infection in immunocompetent adults

Acute hepatitis C in immunocompetent individuals is rarely symptomatic and rarely biopsied. Thus, the histologic descriptions of acute hepatitis C remain limited. The histology of 5 cases of acute hepatitis C in adults were studied by selecting cases from the consult and surgical pathology files of a single institution. The 5 individuals, 3 males and 2 females, had an average age at biopsy of 50+/-17 years. They presented with jaundice and other nonspecific abdominal symptoms. The time interval from clinical presentation to biopsy ranged from 2 to 18 weeks. The average alanine aminotransferase/aspartate aminotransferase/alkaline phosphatase at the time of biopsy was 308/73/85 U/L. The average total bilirubin was 5.2 mg/dL. Each individual had a single liver biopsy. The histologic findings of the 2 cases biopsied in close temporal proximity to the initial clinical presentation showed similar histologic findings of mixed portal infiltrates with lymphocytes and neutrophils along with bile ductular proliferation that raised the possibility of down stream biliary tract disease. The lobules showed canalicular cholestasis and mild to moderate inflammation. In the third and fourth case, obtained 8 weeks after presentation, the biopsies showed mild to moderate portal and lobular lymphocytic inflammation, findings that were also present in the last case, obtained 18 weeks after presentation. In conclusion, early after acute hepatitis C viral infection, biopsies can have a cholestatic pattern whereas later biopsies tend to show mild nonspecific portal and lobular lymphocytic inflammation. Proper histologic diagnosis can be aided by an awareness of the various histologic findings, which vary depending on the time interval from clinical symptoms to biopsy.

Blood eosinophilia after living donor liver transplantation for hepatitis C virus-related cirrhosis

BACKGROUND

Differentiating between acute cellular rejection (ACR) and recurrent hepatitis C virus after liver transplantation in hepatitis C virus-positive patients is difficult, but vital for preventing graft loss.

METHODS

The blood eosinophil counts 3 days before or on the day of biopsy were retrospectively reviewed to evaluate their value for predicting ACR in 91 biopsy samples from 45 patients.

RESULTS

Eosinophil counts on the day of biopsy were significantly higher in the ACR group (n = 20) than in the non-ACR (n = 71) group, although the difference was negligible 3 days before the biopsy. A relative eosinophil count of 2% or an absolute eosinophil count of 200 cells/mm(3) predicted ACR with a specificity of 94% or 96%, respectively.

CONCLUSIONS

Blood eosinophil count on the day of biopsy can be helpful in the diagnosis of ACR in patients who underwent living donor liver transplantation for hepatitis C virus-related cirrhosis.

C4d immunopositivity is uncommon in ABO-compatible liver allografts, but correlates partially with lymphocytotoxic antibody status

AIMS

To determine whether C4d immunopositivity helps recognition of humoral rejection in dysfunctional liver allografts.

METHODS AND RESULTS

C4d immunopositivity was retrospectively evaluated in liver allografts. There were three staining patterns: portal venular plexus, sinusoidal and hepatocellular. The latter was related to ischaemic necrosis and not scored as positive. C4d immunopositivity was not encountered in 10 preperfusion or 15 consecutive early protocol biopsies. However, three of 12 early protocol biopsy specimens from crossmatch-positive patients were C4d+, two showing repeated positivity on at least one further biopsy specimen, while others remained negative. C4d was also positive in 2/16 early moderate acute cellular rejections, 3/14 cases of centrilobular necroinflammation, 3/11 biliary obstructions, 3/13 chronic rejections and 1/10 primary non-functional allografts.

CONCLUSION

C4d immunopositivity is uncommon in liver allografts. There is a weak positive correlation with a positive lymphocytotoxic crossmatch and some patterns of allograft dysfunction. The morphological associations resemble those reported in lymphocytotoxic crossmatch-positive patients, plus occasional sinusoidal and hepatocellular injury. Although the practical utility of C4d immunohistochemistry seems limited, it may identify a small subgroup of individuals in whom chronic humoral microvascular injury contributes to allograft dysfunction.

Patterns of recurrent hepatitis C after liver transplantation in a recent cohort of patients

Clinicopathologic trends of recurrent hepatitis C after liver transplantation (LT) in hepatitis C (HCV) patients seem to have changed in recent years. Our aims were to define the current post-LT patterns of HCV recurrence and identify features of diagnostic and/or prognostic significance. Detailed analysis was performed on 92 HCV patients who underwent LT from June 1999 to December 2003 and survived early post-LT period. The study patients were grouped, as follows: no histologic recurrence (n = 31), "typical" recurrent HCV (n = 52), and post-LT autoimmune-like hepatitis ("AIH-like") (n = 9). The typical and AIH-like groups had mostly common features with post-LT progressive fibrosis (stage > or =2) more frequent in the latter. Based on post-LT progressive fibrosis (stage > or =2), the 2 post-LT hepatitis categories were regrouped as progressive (n = 24) and nonprogressive (n = 37). High viral counts, HCV genotype 1, and native liver inflammation grade 2 or higher with plasmacytic periseptitis were more frequent in progressive cases than nonprogressive or nonrecurrent cases. Sex mismatch of male recipient and female donor was more common in nonrecurrent group. Overall, death rate was comparable in all groups; however, post-LT HCV-related deaths were more common in progressive cases. In conclusion (1) two thirds (66.2%) of HCV patients developed histologic hepatitis after LT with either typical or AIH-like features; (2) progressive fibrosis was seen in 39.3% of patients with post-LT hepatitis and 26% of the entire study group and was more frequent in AIH-like cases; (3) inflammation grade 2 or higher with plasmacytic periseptitis in native livers may be a predictor of post-LT progressive fibrosis; and (4) male recipient/female donor combination was more common in nonrecurrent cases.

Early Antiviral Treatment of Hepatitis C Virus Recurrence after Liver Transplantation in HIV-Infected Patients

Objective

To investigate the efficacy of early antiviral treatment for hepatitis C virus (HCV) recurrence in HIV/HCV-coinfected patients undergoing liver transplantation for end-stage liver disease.

Methods

Open prospective trial of early treatment of HCV recurrence in consecutive HIV/HCV-coinfected patients transplanted at a tertiary hospital in Barcelona between 2002 and 2004. All patients had indication for liver transplantation, no previous CDC class C HIV-associated opportunistic events, a CD4+ T-cell count >100 cells/fxl, and undetectable plasma HIV RNA on highly active antiretroviral therapy. Treatment with pegylated interferon-a2b (1.5 μg/kg/week) and ribavirin (800–1000 mg/day) was given for 24 to 48 weeks, as soon as HCV recurrence was histologically documented.

Results

Of six patients who underwent transplant, five patients surviving the early post-transplantation period developed HCV recurrence, presenting as severe cholestatic hepatitis in three, and were started on antiviral treatment a median of 12 weeks (range: 5–31) after transplantation. After a median follow-up of 24 months all treated patients were alive. Biochemical response was achieved in all patients, although only one achieved a sustained virological response. Mild rejection before HCV recurrence occurred in two cases. Treatment was well tolerated with no episodes of rejection or mitochondrial toxicity. No patient required modification of the antiretroviral regimen. Liver biopsies performed in patients without virological response, 12–34 months after transplantation, showed cirrhosis in two and moderate chronic active hepatitis in the remainder.

Conclusions

Despite early antiviral treatment, severe HCV recurrence after liver transplantation may compromise long-term survival in HIV-infected patients. Improved treatment strategies for these patients are urgently required.

Acute rejection in HCV-infected liver transplant recipients: The great conundrum

1. In hepatitis C virus (HCV)-infected patients, treatment of acute rejection is associated with worse outcomes (increased risk of allograft cirrhosis and mortality). 2. Whether patients with HCV are at higher risk for rejection remains controversial. 3. The mechanisms mediating acute rejection and recurrence of HCV are distinct, and as such, it should be possible to develop techniques based on these molecular differences that are diagnostically useful. 4. Liver biopsy is considered the gold-standard for diagnosing acute rejection and recurrent HCV; however, given histopathological similarities between the two conditions, discrimination can be extremely difficult. 5. At the present time, there are no reliable, noninvasive tools available to distinguish between HCV recurrence alone and acute rejection plus HCV recurrence. 6. Mild rejection per se is not associated with graft loss and treatment of rejection with steroids and OKT3 is associated with worse outcome in HCV; thus, it seems logical that we should no longer treat mild rejection.

Early recurrence of hepatitis C virus infection after liver transplantation

1. Early recurrence of hepatitis C is universal. 2. Typical histopathologic features of hepatitis C virus (HCV) and acute allograft rejection (AAR) exist. 3. Early recurrent HCV may be differentiated from AAR. 4. Liver biopsy plays a role in diagnosing HCV and AAR. 5. Risk factors for recurrent HCV should be known. 6. The natural history of recurrent HCV should be known. 7. The future role of ancillary studies beyond liver biopsy is assessed.

Detection of HCV antigens in liver graft: relevance to the management of recurrent post-liver transplant hepatitis C

The aim of this study was to evaluate how the immunohistochemical detection of liver hepatitis C virus (HCV) antigens (HCV-Ag) could support the histologic diagnosis and influence the clinical management of post-liver transplantation (LT) liver disease. A total of 215 liver specimens from 152 HCV-positive patients with post-LT liver disease were studied. Histologic coding was: hepatitis (126), rejection (34), undefined (24; coexisting rejection grade I and hepatitis), or other (31). The percentage of HCV-Ag infected hepatocytes were evaluated, on frozen sections, by an immunoperoxidase technique. HCV-Ag were detectable early in 57% of cases within 30 days post-LT, 92% of cases between 31 and 180 days, and 74% of cases after more than 180 days. Overall, HCV-Ag were detected more frequently in histologic hepatitis as compared to rejection (P < 0.0001) with a higher percentage of positive hepatocytes (P < 0.00001). In 16 patients with a high number of HCV-Ag-positive hepatocytes (65%; range 40-90%) a clinical diagnosis of recurrent hepatitis (RHC) was made despite inconclusive histopathologic diagnosis. Multivariate analysis identified the percentage of HCV-Ag-positive hepatocytes and the time post-LT as independent predictors for RHC (P = 0.008 and P = 0.041, respectively) and the number of HCV-Ag-positive hepatocytes >/=50% as the only independent predictor for nonresponse (P < 0.001) in 26 patients treated with alpha-interferon plus ribavirin. In conclusion, HCV reinfection occurs early post-LT, reaching its peak within 6 months. Immunohistochemical detection of post-LT HCV reinfection support the diagnosis of hepatitis when the histologic features are not conclusive. A high number of infected cells, independently from the genotype, represents a negative predictive factor of response to antiviral treatment.

Clinical tolerance following liver transplantation: long term results and future prospects

The ongoing quest of achieving clinical transplantation tolerance has been fueled, in large part, by the success of solid organ transplantation. Long term morbidity following transplantation now is primarily related to complications of immunosuppression (IS) such as malignancy, drug toxicity, or infection. This report provides long term follow-up on a large cohort of operationally tolerant patients, provides clinical guidelines to be considered in IS withdrawal, and identifies future prospects for achieving consistent clinical tolerance following liver transplantation (LT).

Transplantation pathology

Histological assessments continue to have an important role in the diagnosis and management of graft complications following liver transplantation. For some conditions, such as liver allograft rejection, histology is regarded as the "gold standard" for diagnosis. In other cases, where a likely cause of graft dysfunction has been identified using other methods, liver biopsy provides important additional information (e.g., severity of necroinflammatory activity and fibrosis in recurrent hepatitis C infection) and may point to the presence of an additional or alternative cause for graft dysfunction. In cases where a dual pathology is suspected (eg, hepatitis C and rejection), histological findings can help to identify the main cause of graft dysfunction. This article will focus on the main patterns of damage that are seen in post-transplant liver biopsies and their differential diagnosis. As with the assessment of liver biopsies in the native liver, clinico-pathological correlation is very important. Consideration should also be given to the therapeutic implications of the biopsy report, in particular whether changes in immunosuppression are indicated.

Liver biopsy interpretation for causes of late liver allograft dysfunction

Evaluation of needle biopsies and extensive clinicopathological correlation play an important role in the determination of liver allograft dysfunction occurring more than 1 year after transplantation. Interpretation of these biopsies can be quite difficult because of the high incidence of recurrent diseases that show histopathological, clinical, and serological features that overlap with each other and with rejection. Also, more than one insult can contribute to allograft injury. In an attempt to enable centers to compare and pool results, improve therapy, and better understand pathophysiological disease mechanisms, the Banff Working Group on Liver Allograft Pathology herein proposes a set of consensus criteria for the most common and problematic causes of late liver allograft dysfunction, including late-onset acute and chronic rejection, recurrent and new-onset viral and autoimmune hepatitis, biliary strictures, and recurrent primary biliary cirrhosis and primary sclerosing cholangitis. A discussion of differential diagnosis is also presented.

Interobserver Agreement in Hepatitis C Grading and Staging and in the Banff Grading Schema for Acute Cellular Rejection: The “Hepatitis C 3” Multi-Institutional Trial Experience

Context.—Establishing adequate interobserver agreement is crucial not only for standardization of patient care but also to ensure validity of findings in multi-institutional trials.

Objective.—To evaluate interobserver agreement in assessing chronic hepatitis C (HCV) and acute cellular rejection (ACR) among 17 hepatopathologists involved in the “Hepatitis C 3” trial.

Design.—The trial is a randomized multicenter (17 institutions) study involving 312 patients undergoing transplantation for HCV. Patients are randomized to 3 treatment arms. For final data analysis, all biopsy specimens are reviewed by a central pathologist (G.J.N.). Recurrence of HCV is evaluated according to the Batts and Ludwig schema. The 1997 Banff schema is used to evaluate ACR. To assess interobserver agreement, hematoxylin-eosin–stained sections from 11 liver biopsy specimens (6 HCV and 5 ACR) were sent by the central pathologist to 16 local pathologists from 13 institutions. Statistical analysis was performed on raw ACR/HCV data as well as data grouped according to clinically significant primary endpoint cutoffs.

Results.—Statistically significant agreement was found among all participating pathologists (P &lt; .001). On κ analysis, the degree of agreement was rated “moderate” for HCV grade and stage and ACR global grading (κ = 0.30, 0.33, and 0.37, respectively). Interobserver agreement was weaker for rejection activity index scoring of ACR (κ = 0.15). A stronger degree of agreement was found when scores were grouped based on endpoint cutoffs (κ = 0.76 “almost perfect” for HCV and 0.62 “substantial” for ACR).

Conclusions.—An overall statistically significant interobserver agreement was found among 17 pathologists using the 1997 Banff schema and the Batts and Ludwig schema.

Influence of donor/recipient HLA-matching on outcome and recurrence of hepatitis C after liver transplantation

The aim of this study was to analyze the effect of human leukocyte antigen (HLA) matching on outcome, severity of recurrent hepatitis C and risk of rejection in hepatitis C positive patients after liver transplantation (LT). In a retrospective analysis, 165 liver transplants in patients positive for hepatitis C virus (HCV) with complete donor/recipient HLA typing were reviewed for recurrence of HCV and outcome. Follow-up ranged from 1 to 158 months (median, 74.5 months). Immunosuppression consisted of either cyclosporine-A- or tacrolimus-based quadruple induction therapy including or an interleukin 2-receptor antagonist. Protocol liver biopsies were performed after 1, 3, 5, 7, and 10 years and staged according to the Scheuer scoring system. The overall 1-, 5-, and 10-year graft survival figures were 81.8%, 69.11 and 62%, respectively. There was no correlation in the study population between number of HLA mismatches and graft survival. The number of rejection episodes increased significantly in patients with more HLA mismatches (P < 0.05). In contrast to this, the fibrosis progression was significantly faster in patients with 0-5 HLA mismatches compared to patients with a complete HLA mismatch. In conclusion, HLA matching did not influence graft survival in patients after LT for end-stage HCV infection, however, despite less rejection episodes, the fibrosis progression increased in patients with less HLA mismatches within the first year after LT.