Autoimmune hepatitis. Definition--classification--histopathology--immunopathogenesis

Autoimmune hepatitis (AIH) is a distinct form of acute and chronic inflammatory liver disease in which immune reactions against host antigens are found to be the major pathological mechanism. If left untreated it carries an unfavourable prognosis, and the diagnosis should be made as soon as possible. The diagnostic approach has been greatly facilitated by the establishment of a panel of marker autoantibodies, which do not define distinct therapeutic groups of AIH, but do allow a subgrouping based on differences in patient populations, some clinical features and prognosis. The characterization of organ-specific components of the liver cell surface as targets of cellular and humoral autoimmune reactions give new insights into the pathogenesis of the disease, even though the primary event triggering the disease remains to be defined. The most important disease-promoting factor seems to be a genetically determined background for autoimmunity. Without this different environmental factors, including viruses, toxins, cytokines and drugs, are only able to induce transient autoimmune phenomena and not autoimmune disease. The histopathology of AIH is in keeping with the present pathogenetic concept. Although there is no pathognomonic feature distinguishing this type of hepatitis from virus-induced forms, some distinct morphological lesions are regarded as characteristic. Clinical research on AIH has benefited greatly from observations of experimental AIH in mice. Recognition of the critical role of autoreactive T-lymphocytes in the pathogenesis and the observation of spontaneous recovery from AIH in the animal model associated with antigen-specific and antigen-non-specific T-cell suppression have made basic contributions to our improved understanding of the natural course of AIH in humans.

[Incidence of post-transfusion hepatitis in Hungary 1987-1993]

The authors describe the epidemiological characteristics of hepatitis cases occurred after administration of blood or blood-preparations in Hungary, based on data collected between January 1987 and December 1993. The epidemiologists of the public health network reported 868 acute posttransfusion hepatitis within this seven years period. The number of the cases decreased year by year, and in accordance with the rapid development of virological diagnostics the rate of cases with uncovered aetiology increased gradually. Nevertheless the aetiology of more than half of the reported cases (466 patients, i.e. 53.6%) remained unknown. The results of the examinations were negative in 167 cases (19.2%), and no etiological examinations were carried out in 299 cases (34.4%). Hepatitis A was reported in 17 cases (2%), hepatitis B in 129 cases (14.9%), whilst non-A, non-B hepatitis was diagnosed in 188 cases based on examinations with an experimental NANB antigen and antibody tests or by exclusion of hepatitis A and B infectious (21.7%); from 1991 67 cases (7.7%) were diagnosed by standard tests as hepatitis C, and Epstein-Barr virus infection was reported in 1 case (0.1%). During the seven years 11 patients of the 868 (1.3%) died in the acute phase of the illness.

[Autoimmune hepatitis and hepatitis C]

From autoimmune hepatitis (AIH) classification which recognizes three types of AIH, we discuss the main relations between hepatitis C virus (HCV) infection and AIH. Type I AIH is associated with antinuclear and antismooth muscle antibodies, and with other autoimmune diseases. There is no relation between type I AIH and HCV. Type I anti-liver kidney microsome and anti-liver cytosol I antibodies represent the hallmark of type II AIH. Among type II AIH, two subgroups emerged: type IIa AIH (10-40%) are true AIH (sensitive to steroids but worsens with interferon alpha), whereas type IIb AIH (60-90%) appear as a particular form of HCV hepatitis. Type IIb AIH have a moderate activity, a low titer of autoantibodies, anti-GOR antibodies but never anti-liver cytosol I, no sensitivity to steroids but are sensitive to interferon alpha. The hallmark of type III AIH are anti-cytosol antibodies, but these AIH have the same characteristics as type I AIH. The classification between true AIH (I, IIa, III) or "pseudo-AIH" due to HCV infection has major therapeutic implications. Steroids or immunosuppressive treatments are effective in type I, IIa and III AIH but have no efficacy in type IIb AIH. Alpha interferon has an efficacy in type IIb AIH, but it has no efficacy and may even worsen hepatitis in type I, IIa and III AIH.

[Evaluation of the new international classification of chronic hepatitis]

Evaluation of the new international classification of chronic hepatitis recommended by International congress of gastroenterologists in 1994 is given. Positive aspects of the classification cover the necessity of indicating etiological trend, process activity, the disease staging. Some negative points are also mentioned.

Chronic hepatitis. An update on terminology and reporting

The terms chronic active hepatitis (CAH), chronic persistent hepatitis (CpH), and chronic lobular hepatitis (CLH) have become obsolete, and their use without further specifications should be discontinued. This recommendation has become necessary because these names have changed from descriptive terms, intended for grading, to terms that are used either as morphologic diagnoses or disease designations or both, depending on individual preferences. Because this practice has caused serious misunderstandings, many authors and two international groups have recommended the use of a clear etiologic terminology. For the reporting practice of pathologists, we recommend that the pathologist routinely sign out biopsy samples with features of chronic hepatitis by indicating etiology, grade, and stage. An example would be autoimmune hepatitis, severe, stage 3. The stage in this case would indicate the presence of well-developed septal fibrosis but no nodular regeneration. Obviously, for the etiologic diagnosis, morphologic findings must be integrated with clinical and laboratory data. If this information is not available, clear morphologic diagnoses should be reported. Thus, instead of CPH, the diagnosis should be portal hepatitis, cause undetermined. This reporting practice eliminates ambiguous terminology and avoids the risk of inappropriate treatment as might occur, for example, when a term such as CAH is used to describe Wilson's disease and is misunderstood to mean autoimmune hepatitis. For a transitional period and to facilitate relearning, the terms CAH, CPH, and CLH can be reported in parentheses behind the etiologic diagnosis.

Segregation of pANCA antigenic recognition by DNase treatment of neutrophils: ulcerative colitis, type 1 autoimmune hepatitis, and primary sclerosing cholangitis

Antineutrophil cytoplasmic antibodies (ANCA) have been identified in the serum of 50-80% of ulcerative colitis (UC) patients. UC-associated ANCA yield a perinuclear staining pattern (pANCA) with alcohol-fixed neutrophils. More recently, pANCA have been detected in the serum of patients with primary sclerosing cholangitis (PSC) and other autoimmune liver diseases. Up to 70% of PSC patient sera and up to 92% of sera from patients with well-defined type 1 autoimmune hepatitis (type 1 AIH) were found to express pANCA. Such expression by patients with PSC and type 1 AIH raises questions concerning the relationship of these pANCA to each other and to that of UC. Differences and similarities in pANCA characteristics are found among the three diseases, suggesting the use of pANCA to define specific disease subgroups. Our recent finding that the UC-associated pANCA reactive antigen was localized within the nuclear domain prompted an examination of whether DNase treatment of neutrophils would alter antigenic recognition by the pANCA of UC, PSC, and type 1 AIH. While loss of antigenic recognition after DNase digestion of neutrophils was a dominant feature of the UC-associated pANCA, the majority of PSC and type 1 AIH pANCA recognized cytoplasmic constituents. These results further support the feasibility of defining and/or distinguishing disease subgroups based on the characterization of respective pANCA.

The validity and importance of subtypes in autoimmune hepatitis: a point of view

OBJECTIVE

To advocate formal subclassification of autoimmune hepatitis into two types based on the presence of mutually exclusive immunoserological markers, target antigen diversity, contrasting genetic predispositions, and differences in clinical profile and behavior.

METHODS

Relevant references in English were identified through a Medline Search (1984-1994) and through a personal library of journals and reprints.

RESULTS

Antinuclear antibodies and/or smooth-muscle antibodies are mutually exclusive of antibodies to liver/kidney microsome type 1. The cytochrome monooxygenase P450 IID6 is the target autoantigen for patients with antibodies to liver/kidney microsome type 1, and patients with these autoantibodies are different from others. The human lymphocyte antigens DR3 and DR4 are risk factors for patients with antinuclear and/or smooth-muscle antibodies, whereas the B14, DR3, and C4A-QO antigens are common in patients with antibodies to liver/kidney microsome type 1. Patients with antibodies to liver/kidney type 1 are younger, and they more commonly have concurrent organ-specific autoantibodies and/or immunological diseases than counterparts with antinuclear and/or smooth-muscle antibodies. They also progress to cirrhosis more frequently.

CONCLUSIONS

Two distinct types of autoimmune hepatitis can be defined by immunoserological markers, genetic predispositions, autoantigen status, and clinical features. Each should be recognized as a valid and independent entity.

[Morphologic classification of chronic hepatitis]

The diagnosis of chronic hepatitis (CH) should include the information on CH etiology, the presence or absence of CH activity as well as its morphological characteristics. CH may be of a viral etiology (the type of the virus should be mentioned in the diagnosis), autoimmune, drug-induced and alcoholic. The etiology can be established by means of the clinicomorphological analysis using immunological and immunohistochemical techniques. Sometimes it is possible to do so after routine staining of biopsies. Portal, lobular and periportal hepatitis are distinguished morphologically. Instead of the indefinite term chronic persisting hepatitis it is recommended to recognize active and non-active hepatitis.

Autoimmune hepatitis: classification, heterogeneity, and treatment

Autoimmune hepatitis, a chronic necroinflammatory disorder of unknown etiology, is characterized by immunologic and autoimmunologic features. It is more prevalent in women than in men, and genetic factors appear to play a major role in the disease. The classification of autoimmune hepatitis is based on circulating autoantibody status; however, heterogeneity is distinguished not only by autoantibodies, but by histologic differences, a variety of clinical features, immunogenetic status, and probably pathogenesis. Presentation extends from the asymptomatic to the severely ill patient. Although patients may present with or without evidence of circulating autoantibodies, hyperglobulinemia is a rather consistent laboratory feature. Because the disease is generally steroid-responsive, therapeutic remission rates of 60-80% have been achieved with prednisone or a combination of prednisone and azathioprine, and many patients can be maintained with these drugs alone or in combination. There are no firm guidelines for decisions regarding withdrawal or reduction of medication. When treatment failures occur, orthotopic liver transplantation may be required.

[Autoimmune hepatitis]

Acute and chronic autoimmune hepatitis are uncommon inflammatory liver diseases, mainly occurring in young women, in association with hypergammaglobulinemia and serum autoantibodies. Different types have been described: type 1 characterized by anti-smooth muscle and anti-nuclear antibodies; type 2 characterized by anti-LKM1 antibodies; type 3 characterized by anti-SLA antibodies. Other types, still not clearly defined, may exist. Autoimmune hepatitis are associated with HLA A1 B8 DR3 and HLA DR4. Without any treatment, the disease leads to cirrhosis and, uncommonly, to fulminant hepatitis. Large doses of corticosteroids usually allow to control the disease. Relapse of hepatitis is frequent after corticosteroid withdrawal. Concomitant administration of immunosuppressive agents such as azathioprine allows to reduce corticosteroid dosage and contributes to maintain the remission of the disease. Liver transplantation may be indicated in cases of severe cirrhosis or fulminant hepatitis.

[Chronic autoimmune type II hepatitis with various extrahepatic clinical manifestations]

We present the case of a patient with autoimmune chronic hepatitis and anti-LKM antibodies, who developed associated autoimmune diseases, cyclic nodose erythema, bilateral peripheric paralysis, idiopathic thrombocytopenic purpura and diabetes mellitus. We describe the first signs of the disease and how three different forms can be differentiated depending on the type of autoantibodies present in the patients' serum. Finally, we list several forms of presentation of the disease, the potential clinical associations with other autoimmune processes and the potential immunological basis for the development of the hepatic lesion.

A practical approach to the liver biopsy

A stepwise practical approach to the histological interpretation of liver biopsy specimens is presented. To avoid bias, liver biopsies are analysed blind initially to arrive at a morphologic diagnosis. The possible differential diagnoses are then considered in order of likelihood. The final diagnosis is made only after clinicopathologic correlation; the importance and necessity of discussion with the referring clinician cannot be overemphasized. Common morphologic categories are given as guide-lines. Helpful histopathologic features for the various differential diagnoses including diagnostic problems and pitfalls are highlighted.

[Problem of chronic hepatitis (classification, pathogenesis and treatment]

Update information is added to classification of chronic hepatitis. A new form--chronic lobular hepatitis is described as well as characteristic features of immune response to hepatitis B virus (HBV). The findings enable the authors not only to relate autoimmune abnormalities to HBV infection, but to consider them an essential component of this infection. The leading role in pathogenesis of viral hepatic lesions is played by cellular immunity. A sound subpopulation analysis of immunocompetent blood cells was carried out for chronic active hepatitis and hepatic cirrhosis in correlation with HBsAg. It is emphasized that a biological cycle of HBV development determines the type and power of the macroorganism immune response and should be allowed for when designing policy of treatment of chronic hepatic viral diseases. Criteria are proposed for deciding on immunomodulators and immunodepressants for chronic viral and autoimmune hepatitis.