Liver biopsy interpretation in hepatitis. Part II: Histopathology and classification of acute and chronic viral hepatitis/differential diagnosis

A deep-learning-based model for assessment of autoimmune hepatitis from histology: AI(H)

Histological assessment of autoimmune hepatitis (AIH) is challenging. As one of the possible results of these challenges, nonclassical features such as bile-duct injury stays understudied in AIH. We aim to develop a deep learning tool (artificial intelligence for autoimmune hepatitis [AI(H)]) that analyzes the liver biopsies and provides reproducible, quantifiable, and interpretable results directly from routine pathology slides. A total of 123 pre-treatment liver biopsies, whole-slide images with confirmed AIH diagnosis from the archives of the Institute of Pathology at University Hospital Basel, were used to train several convolutional neural network models in the Aiforia artificial intelligence (AI) platform. The performance of AI models was evaluated on independent test set slides against pathologist's manual annotations. The AI models were 99.4%, 88.0%, 83.9%, 81.7%, and 79.2% accurate (ratios of correct predictions) for tissue detection, liver microanatomy, necroinflammation features, bile duct damage detection, and portal inflammation detection, respectively, on hematoxylin and eosin-stained slides. Additionally, the immune cells model could detect and classify different immune cells (lymphocyte, plasma cell, macrophage, eosinophil, and neutrophil) with 72.4% accuracy. On Sirius red-stained slides, the test accuracies were 99.4%, 94.0%, and 87.6% for tissue detection, liver microanatomy, and fibrosis detection, respectively. Additionally, AI(H) showed bile duct injury in 81 AIH cases (68.6%). The AI models were found to be accurate and efficient in predicting various morphological components of AIH biopsies. The computational analysis of biopsy slides provides detailed spatial and density data of immune cells in AIH landscape, which is difficult by manual counting. AI(H) can aid in improving the reproducibility of AIH biopsy assessment and bring new descriptive and quantitative aspects to AIH histology.

Herpes Simplex Virus Hepatitis: A Brief Review of an Oft-overlooked Pathology

Herpes simplex virus (HSV) is a rarely reported cause of viral hepatitis. Aggressive in nature, most cases of HSV hepatitis rapidly progress to fulminant hepatic failure. Present day, its pathogenesis is yet to be elucidated, but its complications and associated high mortality rate are clear. Clinically, its symptoms mimic those of other causes of acute hepatic failure thus making the diagnosis of HSV hepatitis a precarious task. Although treatment in the form of acyclovir is readily available, most cases have a poor prognosis due to late initiation of therapy. This makes the early identification of HSV essential in improving outcomes and potentially preventing mortality.

Megamitochondria formation in hepatocytes of patient with chronic hepatitis C - a case report

Although chronic hepatitis C virus (HCV) infection affect 185 million people world-wide, pathomechanism of liver damage is still unclear. Electron microscopy can reveal liver injury in very early stage and help understanding the mechanisms that is crucial in the pathogenesis of chronic hepatitis C. We present the morphological changes in the liver of HCV infected 24-year-old female patient, using light and transmission electron microscopy. Examination by TEM revealed wide range of specific subcellular abnormalities in hepatocellular ultrastructure. The most common observed changes were ring-shaped nuclei with intranuclear inclusion, megamitochondria, and “membranous web” structures – the hallmark of RNA-viruses infection.

Significance of liver histology in HBsAg-positive, IgM anti-HBc-negative acute hepatitis B virus-related hepatitis

AIMS

The natural course of HBsAg-positive, IgM anti-HBc-negative acute hepatitis B virus (HBV)-related hepatitis is unclear. The aim of this study was to evaluate the prognostic significance of histological features and hepatic expression of HBV antigens in such patients.

METHODS AND RESULTS

Fifty patients with HBsAg-positive, IgM anti-HBc-negative acute hepatitis B who underwent liver biopsy during the acute hepatitis episode were studied [HBeAg seroconversion (n = 16), persistently positive for HBeAg (n = 9), and persistently negative for HBeAg (n = 25)]. Twenty-six cases had features of typical acute hepatitis only (group A), and 24 cases had changes suggesting pre-existing chronic hepatitis (group B). HBcAg and/or HBsAg immunoreactivity was detected less frequently in group A than in group B (31% versus 79%, P = 0.01). HBsAg clearance was observed in 24% of patients, almost exclusively in cases with HBeAg seroconversion. HBsAg loss was significantly more frequent in group A than in group B (52% versus 0%, P < 0.001), and in cases without rather than with immunohistochemical expression of HBV antigens (55% versus 0%, P < 0.001). In group A, HBsAg clearance was observed in 80%, 54% and 0% of patients with mild, moderate or severe acute hepatitis, respectively (P < 0.034).

CONCLUSIONS

Histological information is very important for the prognosis of HBsAg-positive, IgM anti-HBc-negative acute hepatitis B. HBeAg seroconversion with underlying typical acute hepatitis changes of mild to moderate severity without hepatic expression of HBV antigens strongly predicts subsequent HBsAg loss.

Natural killer cells inhibit hepatitis C virus expression

Natural killer (NK) cells are critical in host innate defense against certain viruses. The role of NK cells in controlling hepatitis C virus (HCV) remains obscure. We examined whether NK cells are capable of inhibiting HCV expression in human hepatic cells. When NK cells are cultured with the HCV replicon-containing hepatic cells, they have no direct cytolytic effect but release soluble factor(s) suppressing HCV RNA expression. Media conditioned by NK cell lines (NK-92 and YTS) or primary NK cells isolated from healthy donors contain interferon gamma (IFN-gamma) and potently inhibit HCV RNA expression. Ligation of CD81 on NK cells inhibits IFN-gamma production and results in decreased anti-HCV activity. In addition, the antibodies to IFN-gamma or IFN-gamma receptors abolish the anti-HCV activity of NK cell-conditioned media. The role of IFN-gamma in NK cell-mediated, anti-HCV activity is supported by the observation that NK cell-conditioned media enhanced expression of signal transducer and activator of transcription-1, a nuclear factor that is essential in IFN-gamma-mediated antiviral pathways. NK cell-conditioned media have the ability to stimulate intracellular IFN-alpha expression in the hepatic cells, suggesting a mechanism responsible for NK cell-mediated, anti-HCV activity. Thus, NK cells hold the potential to play a vital role in controlling HCV replication in hepatic cells using an IFN-gamma-dependent mechanism.

Inhibition of natural killer cells through engagement of CD81 by the major hepatitis C virus envelope protein

The immune response against hepatitis C virus (HCV) is rarely effective at clearing the virus, resulting in approximately 170 million chronic HCV infections worldwide. Here we report that ligation of an HCV receptor (CD81) inhibits natural killer (NK) cells. Cross-linking of CD81 by the major envelope protein of HCV (HCV-E2) or anti-CD81 antibodies blocks NK cell activation, cytokine production, cytotoxic granule release, and proliferation. This inhibitory effect was observed using both activated and resting NK cells. Conversely, on NK-like T cell clones, including those expressing NK cell inhibitory receptors, CD81 ligation delivered a costimulatory signal. Engagement of CD81 on NK cells blocks tyrosine phosphorylation through a mechanism which is distinct from the negative signaling pathways associated with NK cell inhibitory receptors for major histocompatibility complex class I. These results implicate HCV-E2-mediated inhibition of NK cells as an efficient HCV evasion strategy targeting the early antiviral activities of NK cells and allowing the virus to establish itself as a chronic infection.

Gammadelta T cell activation by chronic HIV infection may contribute to intrahepatic vdelta1 compartmentalization and hepatitis C virus disease progression independent of highly active antiretroviral therapy

HIV and hepatis C virus (HCV) coinfection is frequently associated with rapid progression of HCV-related disease, resulting in a higher risk of cirrhosis. Data suggest that natural T cells expressing the Vdelta1 T cell receptor rearrangement are recruited in the liver of chronically HCV-infected patients and are increased in the peripheral blood of HIV-infected persons. We studied gammadelta T cell distribution in the peripheral blood and liver of HCV-infected and HIV/HCV-coinfected patients in the presence and absence of antiretroviral therapy. We observed that Vdelta1+ T cells releasing helper T cell type 1 cytokines are compartmentalized not only in the liver of HCV+ patients, but also of HIV/HCV-coinfected persons. HIV/HCV patients showed an increased frequency of both peripheral and intrahepatic Vdelta1 natural T lymphocytes, resulting in a higher degree of hepatic inflammation when compared with patients with other liver diseases. Finally, highly active antiretroviral therapy (HAART) was unable to restore Vdelta1T cell circulation to normal levels in chronically HIV-infected persons. We conclude that gammadelta T lymphocytes released from tissue to the bloodstream circulation under the influence of chronic HIV infection may contribute to intrahepatic Vdelta1 compartmentalization and progression of liver disease, independently of HAART.

Influence of IFN-alpha on plasma erythropoietin levels in patients with hepatitis B virus-associated chronic active hepatitis

The influence of 3-month interferon-alpha (IFN-alpha) treatment on plasma erythropoietin (EPO) concentration in patients with chronic active hepatitis (CAH) induced by hepatitis B virus (HBV) infection was investigated. The study was carried out in 44 nonanemic patients divided into two groups: CAH B, 30 subjects not treated with IFN-alpha, and CAH B-IFN, 14 subjects treated with IFN-alpha for the first 3 months of the study (5 MU/m(2) body surface subcutaneously (s.c.) three times per week). In all patients, blood samples were taken at the beginning of the study (0) and after 1, 2, 3, 6, 9, and 12 months of observation. At the beginning, plasma EPO levels in the CAH B (27.8 +/- 2.21 mU/ml) and CAH B-IFN (27.3 +/- 3.04 mU/ml) groups did not differ significantly from each other and were significantly higher (p < 0.0001) than in healthy subjects (10.4 +/- 1.06 mU/ml). In patients in the CAH B group, plasma EPO concentrations did not change significantly during the whole observation period. In patients in the CAH B-IFN group, a transient, significant increase in plasma EPO level was found. The highest plasma EPO concentration in this group was noted after the third month of treatment (41.1 +/- 3.41 mU/ml). In conclusion, patients with CAH induced by HBV infection are characterized by increased plasma EPO concentrations, and IFN-alpha treatment in these patients causes a transient increase in the plasma EPO level.

Vigorous peripheral blood cytotoxic T cell response during the acute phase of hepatitis C virus infection

After infection by hepatitis C virus (HCV), a minority of patients develop acute symptomatic disease and some of them are able to clear the virus. In this study, we analyzed peripheral blood mononuclear cells from nine patients with acute symptomatic disease with respect to their cytotoxic T lymphocyte (CTL) response using a panel of HCV-derived peptides in a semiquantitative secondary in vitro culture system. We could detect early CTL responses in 67% of these patients. The CTL responses were directed against multiple viral epitopes, in particular within the structural (core 2-9, core 35-44, core 131-140, and core 178-187) and nonstructural regions of the virus (NS3 1073-1081, NS3 1406-1415, NS4 1807-1816, NS5 2252-2260, and NS5B 2794-2802). We compared the CTL responses displayed by recently and chronically infected HLA-A2-positive patients. Virus-specific CTLs were detectable in chronic carriers but the percentage of positive peptide-specific CTL responses was significantly higher in recently infected patients (P = 0.002). Follow-up of recently infected patients during subsequent disease development showed a significant decrease in the values and proportions of positive peptide-specific CTL responses (P = 0.002 and 0.013, respectively). Patients with limited viral replication exhibited significantly more vigorous early responses (P = 0.024). These data suggest a protective role for the early antiviral CTL response in HCV infection.

Immunohistochemical detection of collagen type III and IV in relation with transformation of Ito cells in liver sinusoids of patients with reactive biliary hepatitis

Reactive biliary hepatitis is a defined morphological entity, which is a result of chronic diseases of the gall bladder, biliary ducts or pancreas. The aim of the present study was to describe the morphology of reactive biliary hepatitis and its significance for progression of liver fibrosis, and in particular Ito cell (fat storing cell) transformation and occurrence of collagen type III and IV in the liver. Liver tissue from 19 patients with reactive biliary hepatitis was investigated light microscopically and immunohistochemically. Histologically, the liver showed features of mild to severe portal and lobular inflammation. The number of Ito cells increased periportally and pericentrally. Deposition of collagen type III and IV was increased in portal tracts, septa and perisinusoidal spaces, mainly in periportal zones of the lobules. Ultrastructurally, collagen type III immunoreactive fibrillar networks were found to be increased in the space of Disse around transitional cells. Collagen type IV immunoreactive deposits were detected around newly proliferating bile ducts in portal stroma and in the space of Disse. Ito cells were mainly transformed into transitional and myofibroblast-like cells. We discuss here the role of Ito cells and certain cytokines in the process of fibrosis of the liver in the course of reactive biliary hepatitis. It is proposed that bile acid retention in bile ducts during non-specific reactive inflammation or a gut endotoxin may cause transformation of Ito cells and increased collagen type III and IV in this type of hepatitis.

Dynamics of intra-hepatic lymphocytes in chronic hepatitis C: enrichment for Valpha24+ T cells and rapid elimination of effector cells by apoptosis

Chronic viral hepatitis is characterized by a dramatic lymphocyte infiltrate in the liver. Although it is one of the most common chronic inflammatory diseases in humans, little information is available on the functional state of these intra-hepatic lymphocytes (IHL). To address this issue, we have optimized cytofluorimetric techniques to assess directly ex vivo the functions, dynamics and repertoires of IHL isolated from biopsies of patients with chronic hepatitis C. We estimate that 1% of the total body lymphocytes infiltrate the inflamed liver and find that, at variance with peripheral blood lymphocytes (PBL) isolated from the same patients, most IHL display an activated phenotype and produce Th1 type lymphokines when stimulated in vitro. Virtually all IHL are found in the G0/G1 state of the cell cycle, while a sizeable percentage of them is undergoing programmed cell death in vivo, as detected by the TUNEL assay performed on freshly isolated cells. In contrast again to PBL from the same patients, IHL show a preferential compartmentalization of NK and TCRgamma/delta+ cells, and a remarkable (up to 20-fold) enrichment for Valpha24+ T cells. Together our data suggest that in a liver injured by chronic hepatitis C, most IHL are pro-inflammatory activated cells which are highly enriched for effectors of innate resistance. These IHL do not undergo clonal expansion in the liver but rather display effector function and die in situ at a high rate, suggesting that maintenance of the IHL pool is dependent on continuous migration from extra-hepatic sites.

Oral lichen planus and HCV infection: a clinical evaluation of 263 cases

BACKGROUND

Hepatitis C virus (HCV) infection induces variable dermatologic manifestations. Our purpose was to determine whether there is an association between HCV infection and oral lichen planus (OLP).

METHODS

Antibodies to HCV were determined in patients with OLP (263 patients; 156 women and 107 men, with a mean age of 55.5 years) and in a control population.

RESULTS

Seventy six cases (28.8%) were positive for HCV antibodies with the second-generation enzyme-linked immunosorbent assay (ELISA II) test. All of these cases were confirmed with the second-generation recombinant immunoblot assay (RIBA II) test. In 61 cases (23.1%), high levels of serum transaminase were found. Positivity for hepatitis B virus (HBV) markers was found in 31 patients (11.7%) and for hepatitis A virus (HAV) markers in 43 patients (16.3%). None had positivity for hepatitis D virus (HDV) markers. As a control group, we used 100 patients (58 women and 42 men, with a mean age of 55.3 years) referred to the School of Dentistry of the University of Naples "Federico II," and treated for general dental caries. In the control group, HCV antibody positivity was found in three cases.

CONCLUSIONS

The high prevalence of HCV antibody in this group of patients with OLP, higher than in the healthy population, suggests a link (p = 1.423 x 10(-7), chi-squared test) between these two diseases. These findings stress the importance of liver examination in OLP patients, and the need for other studies on the high susceptibility to hepatitis viruses in the population in the southern part of Europe.

The relationship between hepatitis C virus and schistosomiasis: histopathologic evaluation of liver biopsy specimens

The reported high incidence of anti-HCV seropositivity in the Egyptian population seems surprising. Some suggest that schistosomiasis is the responsible factor, either by producing false positivity for HCV antibodies or by predisposing to actual HCV infection in some way. In an attempt to investigate this unclear relationship on a histological level, we performed a thorough semiquantitative morphological study of liver biopsy specimens from 44 anti-HCV-positive Egyptian patients with chronic liver disease. More than half of these patients (23) had serological evidence of schistosomiasis. The results have shown that all 44 liver biopsy specimens demonstrated the histopathological features known to be characteristic of chronic HCV hepatitis. Statistical analysis showed no significant difference between the schistosomal and nonschistosomal groups regarding the semiquantitative histological scores of these features. This study confirms the presence of definite HCV-induced hepatic pathology in all anti-HCV seropositive cases. More importantly, it shows the lack of enhancement of this pathology in the schistosomal patients.

Histopathology and pathobiology of hepatotropic virus-induced liver injury

The present report concerns current knowledge regarding immunopathogenesis that can be applied in the interpretation of histopathological changes in acute and chronic viral hepatitis. The histopathological features of viral hepatitis have not been changed and light microscopic examination remains essential for making a diagnosis and classification of chronic hepatitis and for the provision of objective parameters on grading and staging. However, new understanding and knowledge of viral pathogenesis, host immune responses, the biological behaviour of the causative viral agents and, in particular, viral interference in multiple hepatotropic viral infections must be taken into consideration in the interpretation of histopathological and immunopathological findings of liver tissues. This report also presents some histopathological analyses on multiple hepatotropic viral infections. It can be concluded that the diagnostic histological criteria for acute hepatitis remain applicable in such settings. However, the cause of acute flare up in chronic hepatitis could not be determined without clinical, virological and serological information. Routine histopathology cannot distinguish a new infection from an acute exacerbation due to a high level of viral replication or mutant virus. A repertoire of immunocytochemical stainings for viral antigens is helpful, but caution must be exercised in suggesting a specific viral aetiology due to the fact that suppression of pre-existing viral antigens can be pronounced when the new or concurrent infection is hepatitis C virus related.

Hepatitis C virus infection in Italian patients with oral lichen planus: a prospective case-control study

To assess the aetiology of liver disease associated with lichen planus, we prospectively studied 70 consecutive newly diagnosed patients with oral lichen planus (OLP) living in northwest Italy (Piemonte) and 70 controls matched for age and sex with other oral keratoses coming from the same district. Twenty-two patients with OLP (31.4%) and 9 controls (12.9%) were found to be affected by chronic liver disease (CLD) (P = 0.014). In sixteen of the 22 OLP patients with CLD the liver disease was hepatitis C virus (HCV)-related, whereas 2 of the 9 controls had a HCV-related CLD (P = 0.016). In another OLP case, liver damage was related to a combination of HCV and alcohol abuse. The prevalence of HCV antibodies in the whole OLP group (27.1%) was significantly higher than in controls (4.3%) (P = 0.014), whereas no difference was found between the OLP and control groups regarding hepatitis B virus markers and other common causes of CLD. HCV infection was more frequently found in patients with erosive OLP (58.8%) than in patients with non-erosive OLP (13.2%) (P = 0.004). Serum HCV-RNA was detected by polymerase chain reaction (RT-PCR) in the majority (93.7%) of OLP patients who had HCV antibodies. Excluding OLP and control patients with HCV markers, there was no difference between the two groups regarding frequency of CLD. Our data show that HCV is probably the main pathogenic factor in liver disease of Italian patients with OLP, and suggests that HCV could be involved in the pathogenesis of OLP.

Ductular structures in acute hepatitis with panacinar necrosis

The development of ductular structures in acute hepatitis with panacinar necrosis was studied in 15 cases of fulminant hepatitis with variable clinical duration, using immunohistochemical markers. The immunophenotype of ductular structures was assessed by the expression of two bile duct epithelium determinants, wide spectrum cytokeratin and epithelial membrane antigen (EMA), and by their glycoconjugate expression using the specific binding lectins Dolichos biflorus agglutinin (DBA) and soybean agglutinin (SBA). Ductular structures showed a predilective, but not a strictly selective location in acinar zone 1 and at the periphery of newly formed parenchymal nodules. All were positive for keratin, while EMA and the lectins were identified less frequently. Cytokeratin expression was additionally observed in hepatic cells with no other phenotypic alteration: this occurred along isolated hepatic cords, within parenchymal remnants, in the spared parenchyma in acinar zone 1 and occasionally at the periphery of parenchymal nodules. The presence of cytokeratin expression in liver cell plates in association with intermediate morphological stages of tubular remodelling speaks in favour of biliary metaplasia of hepatocytes. This process may represent a phenotypic-functional accommodation of hepatocytes to an altered microenvironment, due to loss of parenchymal integrity. During the phenotypic shift, altered cytokeratin expression appears as one of the earliest biliary features, while EMA and the expression of glycoconjugates represent maturation markers.

Oral lichen planus and hepatitis C virus (HCV) infection: is there a relationship? A report of 10 cases

Ten patients are reported suffering from oral lichen planus (OLP) associated with chronic liver diseases linked to HCV. All patients were affected by varieties of erosive oral lichen planus. In six of these 10 patients the diagnosis of HCV was made as a result of the OLP diagnosis and four of them had unknown, but severe, chronic liver disease. These preliminary data support the possible existence of a relationship between oral erosive lichen planus and HCV infection.

The common pattern of cytokeratin alteration in alcoholic and cholestatic liver disease is different from that of hepatitic liver damage. A study with the panepithelial monoclonal antibody lu-5

The patterns of cytokeratin as determined by murine monoclonal antikeratin antibody lu-5 (mAb lu-5) were quantitated in paraffin-embedded liver tissue from normal and diseased subjects. In tissue from healthy medical students, mAb lu-5 was found to decorate 2-4 periportal and 2-3 perivenular cell layers. Alcoholic liver disease was accompanied by a marked increase in intensity of mAb lu-5 antigen expression in zone I and III hepatocytes. Moreover, additional liver cells of both zones were progressively recruited, so that in advanced lesions all three lobular zones became positive. In mechanical as well as in drug-induced cholestasis, a similar increase of mAb lu-5 antigen expression was already observed in earlier stages of disease, including an earlier recruitment of zone II hepatocytes. In both alcoholic and cholestatic biopsies the intensity and extent of mAb lu-5 epitope expression increased with the duration and severity of disease. In primary biliary cirrhosis (PBC) and seemingly also in primary sclerosing cholangitis the increase and extent was more marked in zone I, the zone of assumed cholate accumulation. Changes in zone III, the territory of histologic cholestasis (bilirubinostasis), became evident only in late stages of PBC. Mallory bodies of alcoholic and cholestatic liver disease showed an identical mAB lu-5 antigen expression, thus giving rise to four different staining patterns. Changes of cytokeratin expression are similar in alcoholic and cholestatic liver diseases. In chronic viral hepatitis, however, cytokeratin alterations are discrete and restricted to precirrhotic/cirrhotic stages.

Compartmentalization of T lymphocytes to the site of disease: intrahepatic CD4+ T cells specific for the protein NS4 of hepatitis C virus in patients with chronic hepatitis C

The adult liver is an organ without constitutive lymphoid components. Therefore, any intrahepatic T cell found in chronic hepatitis should have migrated to the liver after infection and inflammation. Because of the little information available on the differences between intrahepatic and peripheral T cells, we used recombinant proteins of the hepatitis C virus (HCV) to establish specific T cell lines and clones from liver biopsies of patients with chronic hepatitis C and compared them with those present in peripheral blood mononuclear cells (PBMC). We found that the protein nonstructural 4 (NS4) was able to stimulate CD4+ T cells isolated from liver biopsies, whereas with all the other HCV proteins we consistently failed to establish liver-derived T cell lines from 16 biopsies. We then compared NS4-specific T cell clones obtained on the same day from PBMC and liver of the same patient. We found that the 22 PBMC-derived T cell clones represent, at least, six distinct clonal populations that differ in major histocompatibility complex restriction and response to superantigens, whereas the 27 liver-derived T cell clones appear all identical, as further confirmed by cloning and sequencing of the T cell receptor (TCR) variable and hypervariable regions. Remarkably, none of the PBMC-derived clones has a TCR identical to the liver-derived clone, and even with polymerase chain reaction oligotyping we did not find the liver-derived clonotypic TCR transcript in the PBMC, indicating a preferential intrahepatic localization of these T cells. Functionally, the liver-derived T cells provided help for polyclonal immunoglobulin (Ig)A production by B cells in vitro that is 10-fold more effective than that provided by the PBMC-derived clones, whereas there is no difference in the help provided for IgM and IgG production. Altogether these results demonstrate that the protein NS4 is highly immunogenic for intrahepatic CD4+ T cells primed by HCV in vivo, and that there can be compartmentalization of some NS4-specific CD4+ T cells to the liver of patients with chronic hepatitis C.

Recurrence of hepatitis D (delta) in liver transplants: histopathological aspects

BACKGROUND

The viral/pathological correlates of recurrent hepatitis delta virus (HDV) disease in orthotoptic liver transplants are reported.

METHODS

We examined the histological features of recurrent HDV disease in nine patients with transplants for terminal HDV cirrhosis were examined; intrahepatic HDV and hepatitis B virus (HBV) antigens were detected by immunoperoxidase techniques. Sera were tested for the battery of HDV and HBV markers.

RESULTS

In four patients, HDV reinfection was accompanied by the recurrence of an HBV infection with features of active viral replication. In the other five, HDV reinfection was accompanied by an atypical recurrence of HBV infection without evidence of active HBV replication (no expression of intrahepatic hepatitis B core antigen). In four of the latter patients, the atypical HBV pattern changed during the follow-up into a pattern of active viral replication accompanied by chronic necroinflammation detected during histology.

CONCLUSION

The pattern of recurrent HBV infection can influence the pathological aspects of the relapses of HDV disease in liver grafts.

T-lymphocyte response to hepatitis C virus in different clinical courses of infection

BACKGROUND

To assess the role played by the immune response in the outcome of hepatitis C virus infection, the CD4+ T-lymphocyte response to viral antigens was studied in infected individuals with different clinical courses.

METHODS

Using six recombinant proteins of hepatitis C virus, the study assessed the proliferative responses of peripheral blood mononuclear cells from 41 patients with chronic hepatitis C, 11 patients whose chronic hepatitis was successfully treated with interferon alfa and 11 healthy HCV seropositive individuals.

RESULTS

(1) Sixty-five percent of hepatitis C virus-seropositive individuals had CD4+ T-cell responses to viral proteins. (2) All viral proteins were immunogenic for T cells, although NS4 was the most immunogenic. (3) There was a significant correlation between the presence of CD4+ T cell responses to Core and a benign course of infection in healthy seropositives, most of whom were viremic.

CONCLUSIONS

CD4+ T-cell responses to Core, although they do not coincide with virus clearance, are associated with a benign course of infection and may be required to maintain humoral and cellular responses protective against the disease.

Bile duct injury as a part of diagnostic criteria for liver allograft rejection

The decisive criterium of acute liver allograft rejection was found to be the presence of the diagnostic triad of acute rejection; ie, the presence of portal inflammatory mixed infiltrates, venous endothelialitis (both portal and central), and bile duct injury. On the basis of the presence of each of the components of the diagnostic triad, criteria for the diagnosis of different degrees of acute rejection were developed, particularly focusing attention on a detailed analysis of bile duct injury. Bile duct injury was shown to be an essential part of the histopathologic changes in all grades of acute rejection in the liver allograft, the grade of severity of bile duct injury correlating to a certain extent with the grade of severity of acute rejection. Our analyses have made it evident that bile duct injury, which most probably occurs earlier in the process of acute rejection than endothelialitis, is a more sensitive parameter than endothelialitis in the diagnosis of acute rejection. Furthermore, our analyses have revealed that bile duct injury in acute rejection is likely to be an irreversible process, depending on the number of episodes of acute rejection that previously occurred. On the other hand, it has become clear from our results that bile duct injury must not be considered to be an absolute histopathologic marker of acute rejection; however, it does have to be judged synoptically in connection with the other components of the diagnostic triad and the changes that the triad cause in the hepatic parenchyma. Additional analyses of the grade of severity of cholostases have shown that the cholostases are, to a certain degree, an accompanying phenomenon of the histopathologic changes characterizing acute rejection rather than a histopathologic change that is as significant as the presence of the components of the diagnostic triad.

Hepatitis A-like non-A, non-B hepatitis: light and electron microscopic observations of three cases

To date, three types of NANBH have been distinguished by epidemiological, clinical and experimental data. We examined the liver biopsies of three patients with an acute NANBH resembling hepatitis A from the infection route, incubation period and clinical course. The liver biopsies revealed lesions with a portal and periportal predominance, thus also exhibiting parallels with hepatitis A on the histopathological level.

Rapid freezing and frozen sectioning as a means of preserving brain vessel morphometric characteristics

A study was performed for the purpose of determining whether ordinary frozen sections of brain could preserve in vivo parenchymal arteriole morphometric characteristics. The results showed that flash-freezing followed by frozen sectioning is just as reliable a means of preserving brain arteriole morphometric characteristics as the time consuming process of flash-freezing followed by freeze substitution.