Classification of smooth muscle autoantibodies detected by immunofluorescence

Easy recognition and high autoimmune hepatitis specificity of smooth muscle antibodies giving an actin microfilament immunofluorescent pattern on embryonal vascular smooth muscle cells

Smooth muscle antibodies (SMA) with anti-microfilament actin (MF-SMA) specificity are regarded as highly specific markers of type 1 autoimmune hepatitis (AIH-1) but their recognition relying on immunofluorescence of vessel, glomeruli, and tubules (SMA-VGT pattern) in rodent kidney tissue, is restricted by operator-dependent interpretation. A gold standard method for their identification is not available. We assessed and compared the diagnostic accuracy for AIH-1 of an embryonal aorta vascular smooth muscle (VSM) cell line-based assay with those of the rodent tissue-based assay for the detection of MF-SMA pattern in AIH-1 patients and controls. Sera from 138 AIH-1 patients and 295 controls (105 primary biliary cholangitis, 40 primary sclerosing cholangitis, 50 chronic viral hepatitis, 20 alcohol-related liver disease, 40 steatotic liver disease, and 40 healthy controls) were assayed for MF-SMA and SMA-VGT using VSM-based and rodent tissue-based assays, respectively. MF-SMA and SMA-VGT were found in 96 (70%) and 87 (63%) AIH-1 patients, and 2 controls (P < 0.0001). Compared with SMA-VGT, MF-SMA showed similar specificity (99%), higher sensitivity (70% vs 63%, P = ns) and likelihood ratio for a positive test (70 vs 65). Nine (7%) AIH-1 patients were MF-SMA positive despite being SMA-VGT negative. Overall agreement between SMA-VGT and MF-SMA was 87% (kappa coefficient 0.870, [0.789-0.952]). MF-SMA were associated with higher serum γ-globulin [26 (12-55) vs 20 g/l (13-34), P < 0.005] and immunoglobulin G (IgG) levels [3155 (1296-7344) vs 2050 mg/dl (1377-3357), P < 0.002]. The easily recognizable IFL MF-SMA pattern on VSM cells strongly correlated with SMA-VGT and has an equally high specificity for AIH-1. Confirmation of these results in other laboratories would support the clinical application of the VSM cell-based assay for reliable detection of AIH-specific SMA.

Celiac crisis, transient hypertransaminasemia and positive smooth muscle antibodies (SMA): A celiac disease case report

Celiac crisis (CC) is a rare complication of celiac disease (CD), usually observed in younger children with unrecognized CD or poor compliance with a gluten-free diet (GFD). We present a case of celiac crisis in a 3-year-old girl who was recently diagnosed with celiac disease. She was referred to our clinic with anasarca, tetany, and severe malnutrition, with hypokalemia, hypocalcemia, hypomagnesemia, and hypoalbuminemia. During hospitalization, she presented hypertransaminasemia with positive anti-actin smooth muscle antibodies (SMA). Abdominal ultrasound and liver biopsy were normal, excluding autoimmune hepatitis. Liver involvement is a common CD extraintestinal manifestation and cryptogenic form is the most common. SMA positivity could be associated with a systemic immune cross reaction. Our patient normalized liver values after 2 months of GFD.

Autoimmune serology testing in clinical practice: An updated roadmap for the diagnosis of autoimmune hepatitis

Diagnosis of autoimmune hepatitis (AIH) is in most cases challenging for clinicians as there is not a single specific laboratory or histological marker to diagnose or exclude the presence of the disease. The clinical spectrum of AIH varies from completely asymptomatic to acute-severe or even rarely fulminant hepatic failure, while everybody can be affected irrespective of age, gender, and ethnicity. The old revised and the newer simplified diagnostic scores have been established by the International Autoimmune Hepatitis Group (IAIHG) in 1999 and 2008, respectively, which are based on several clinical, laboratory and histological parameters. Additionally, a thorough differential diagnosis from other diseases mimicking AIH is absolutely indicated. In this context, autoantibodies detection in patients with suspected AIH is mandatory -even though not pathognomonic- not only for AIH diagnosis but furthermore, for AIH classification (AIH-type 1 and AIH-type 2). Although autoimmune serology can be supportive of AIH diagnosis in ≥95% of cases if testing has been performed according to the IAIHG guidelines, this is not the case under real-life circumstances in routine clinical laboratories. Clinicians should be careful both for the importance of the required testing and how to interpret the results and therefore, they should communicate and discuss with the laboratory personnel to achieve the maximum benefit for the patient. Herein, a detailed and updated review of the diagnostic work-up for AIH diagnosis under real-life conditions is given to minimize the underestimation and misdiagnosis of AIH which can result in progression of the disease and unfavourable outcomes.

Working Algorithms and Detection Methods of Autoantibodies in Autoimmune Liver Disease: A Nationwide Study

Autoantibody detection is the cornerstone of autoimmune liver diseases (AILD) diagnosis. Standardisation of working algorithms among autoimmunity laboratories, as well as being aware of the sensitivity and specificity of various commercial techniques in daily practice, are still necessary. The aim of this nationwide study is to report the results of the 2020 Autoimmunity Workshop organised by the Autoimmunity Group of the Spanish Society of Immunology and to provide useful information to clinicians and laboratory specialists to improve the management of autoantibody detection in AILD diagnoses. Serum samples from 17 patients with liver diseases were provided by the organisers of the 2020 Autoimmunity Workshop and were subsequently analysed by the 40 participating laboratories. Each laboratory used different techniques for the detection of autoantibodies in each patients’ serum sample, according to their working algorithm. Thus, almost 680 total complete patient reports were obtained, and the number of results from different autoantibody detection techniques was >3000. Up to eight different working algorithms were employed, including indirect immunofluorescence assays (IFA) and antigen-specific techniques (AgST). The IFA of HEp-2 cells was more sensitive than IFA of rat triple tissue for the study of anti-nuclear autoantibodies (ANA) associated with AILD. The IFA of a human neutrophil study for the analysis of anti-neutrophil cytoplasmic autoantibodies was not carried out systemically in all patients, or by all laboratories. AgSTs were the most sensitive methods for the detection of anti-smooth muscle/F-actin, soluble liver antigen, liver cytosol-1, M2-mitochondrial autoantibodies, and ANA associated with primary biliary cholangitis. The main differences in AMA detection were due to patients with autoantibodies against the non-dominant epitope of pyruvate dehydrogenase complex. Given that they are complementary, IFA and AgST should be performed in parallel. If there is high suspicion of AILD, AgST should always be performed.

Autoimmune Hepatitis: Serum Autoantibodies in Clinical Practice

Circulating autoantibodies are a key diagnostic tool in autoimmune hepatitis (AIH), being positive in 95% of the cases if tested according to dedicated guidelines issued by the International Autoimmune Hepatitis Group. They also allow the distinction between type 1 AIH, characterized by positive anti-nuclear and/or anti-smooth muscle antibody, and type 2 AIH, characterized by positive anti-liver kidney microsomal type 1 and/or anti-liver cytosol type 1 antibody. Anti-soluble liver antigen is the only AIH-specific autoantibody, and is found in 20-30% of both type 1 and type 2 AIH. Anti-neutrophil cytoplasmic antibody is frequently positive in type 1 AIH, being associated also with inflammatory bowel disease and with primary/autoimmune sclerosing cholangitis. The reference method for autoantibody testing remains indirect immunofluorescence on triple tissue (rodent liver, kidney and stomach), allowing both the detection of the majority of liver-relevant reactivities, including those autoantibodies whose molecular target antigens are unknown. Of note, the current knowledge of the clinical significance of autoantibodies relies on studies based on this technique. However, immunofluorescence requires trained laboratory personnel, is observer-dependent, and lacks standardization, leading to ongoing attempts at replacing this method with automated assays, the sensitivity, and specificity of which, however, require further studies before they can be used as a reliable alternative to immunofluorescence; currently, they may be used as complementary to immunofluorescence.

Update of the simplified criteria for autoimmune hepatitis: Evaluation of the methodology for immunoserological testing

BACKGROUND & AIMS

The simplified criteria for the diagnosis of autoimmune hepatitis (AIH) include immunofluorescence testing (IFT) of antinuclear and smooth muscle autoantibodies (ANA and SMA) on rodent tissue sections. We aimed to establish scoring criteria for the implementation of ANA IFT on human epithelioma-2 (HEp-2) cells and ELISA-based testing.

METHODS

ANA and SMA reactivity of 61 AIH sera and 72 non-alcoholic fatty liver disease controls were separately assessed on tissue sections and HEp-2 cells to compare the diagnostic value at increasing titers. A total of 113 patients with AIH at diagnosis and 202 controls from 3 European centers were assessed by IFT as well as 3 different commercially available ANA ELISA and 1 anti-F-actin ELISA.

RESULTS

ANA assessment by IFT on liver sections had 83.6% sensitivity and 69.4% specificity for AIH at a titer of 1:40. On HEp-2 cells, sensitivity and specificity were 75.4% and 73.6%, respectively, at an adjusted titer of 1:160. Area under the curve (AUC) values of ANA ELISA ranged from 0.70-0.87, with ELISA coated with HEp-2 extracts in addition to selected antigens performing significantly better. SMA assessment by IFT had the highest specificity for the SMA-VG/T pattern and anti-microfilament reactivity on HEp-2 cells. ELISA-based anti-F-actin evaluation was a strong predictor of AIH (AUC 0.88) and performed better than SMA assessment by IFT (AUC 0.77-0.87).

CONCLUSION

At adjusted cut-offs, both ANA IFT using HEp-2 cells and ELISA-based autoantibody evaluation for ANA and SMA are potential alternatives to tissue-based IFT for the diagnosis of AIH.

LAY SUMMARY

Autoantibodies are a hallmark of autoimmune hepatitis and are traditionally tested for by immunofluorescence assays on rodent tissue sections. Herein, we demonstrate that human epithelioma cells can be used as a reliable substrate for immunofluorescence testing. ELISA-based testing is also a potentially reliable alternative for autoantibody assessment in autoimmune hepatitis. We propose the implementation of these testing methods into the simplified criteria for the diagnosis of autoimmune hepatitis.

Cellular and Molecular Mechanisms of Autoimmune Hepatitis

Autoimmune hepatitis is an uncommon idiopathic syndrome of immune-mediated destruction of hepatocytes, typically associated with autoantibodies. The disease etiology is incompletely understood but includes a clear association with human leukocyte antigen (HLA) variants and other non-HLA gene variants, female sex, and the environment. Pathologically, there is a CD4+ T cell-rich lymphocytic inflammatory infiltrate with variable hepatocyte necrosis and subsequent hepatic fibrosis. Attempts to understand pathogenesis are informed by several monogenetic syndromes that may include autoimmune liver injury, by several drug and environmental agents that have been identified as triggers in a minority of cases, by human studies that point toward a central role for CD4+ effector and regulatory T cells, and by animal models of the disease. Nonspecific immunosuppression is the current standard therapy. Further understanding of the disease's cellular and molecular mechanisms may assist in the design of better-targeted therapies, aid the limitation of adverse effects from therapy, and inform individualized risk assessment and prognostication.

Standardization of Autoantibody Testing in Autoimmune Hepatitis

It is a comment on a recent review published on the Journal.

Serology in autoimmune hepatitis: A clinical-practice approach

Serology is key to the diagnosis of autoimmune hepatitis (AIH). Clinicians need to be aware of which tests to request, how to interpret the laboratory reports, and be familiar with the laboratory methodology. If correctly tested, >95% of AIH patients show some serological reactivity. Indirect immunofluorescence on triple rodent tissue is recommended as first screening step, since it allows the detection of all liver-relevant autoantibodies, except for anti-soluble liver antigen (SLA) antibody, which needs to be detected by molecular based assays. The threshold of immunofluorescence positivity is a titer equal or exceeding 1/40, but for patients younger than 18years even lower titers are clinically significant. Anti-nuclear antibody (ANA) and/or anti-smooth muscle (SMA) antibody characterize type 1 AIH. ANA in AIH typically shows a homogeneous staining pattern on HEp2 cells, without any specific target antigen. Anti-SMA displays different staining patterns on indirect immunofluorescence: the vascular/glomerular (VG) and the vascular/glomerular/tubular (VGT) patterns are considered specific for AIH, whilst the V pattern can be found in a variety of diseases. Type 2 AIH, which is rare and affects mostly children/adolescents, is characterized by anti-liver kidney microsomal 1 and/or anti-liver cytosol 1 antibodies. The presence of anti-neutrophil cytoplasmic antibody (ANCA), particularly atypical p-ANCA (pANNA), points to the diagnosis of AIH, especially in absence of other autoantibodies. Since it is associated with sclerosing cholangitis and inflammatory bowel disease, these conditions have to be ruled out. The only antibody specific for AIH is anti-SLA, which is associated with a more severe disease course.

Diagnostic approach to autoimmune hepatitis

INTRODUCTION

Autoimmune hepatitis (AIH) is a chronic inflammatory liver disease which, if left without treatment, can evolve into cirrhosis and possibly liver failure. The diagnosis of AIH is hampered by the lack of specific and reliable markers of the disease and a number of clinical, biochemical, immunological, histological and genetic factors should be considered to reach a confident diagnosis Areas covered: Clinical expression of AIH, histological features, serological and genetic profiles, differential diagnosis, overlap with other autoimmune liver diseases, assessed on the basis of personal experience and review of published literature in the last 10 years through a systematic Medline search (keywords: autoimmune hepatitis, diagnosis) Expert commentary: Notwithstanding numerous efforts to identify simple and reliable markers of the disease, the diagnosis of AIH is still based on the combination of histological, immunological and biochemical features and often can represent a real challenge for the hepatologist.

Diagnostic autoantibodies for autoimmune liver diseases

Autoimmune liver diseases are conditions of low prevalence that comprise the triad of autoimmune hepatitis, primary biliary cholangitis (cirrhosis) and primary sclerosing cholangitis and their poorly characterised overlapping syndromes. Diagnostic autoantibodies are associated with autoimmune hepatitis and primary biliary cholangitis but not with primary sclerosing cholangitis. Autoantibodies are useful disease markers that facilitate early diagnosis of autoimmune hepatitis and primary biliary cholangitis and allow for therapeutic intervention to prevent progression to liver cirrhosis and associated complications. Adult onset type 1 autoimmune hepatitis is associated with F-actin reactive smooth muscle autoantibody, antinuclear autoantibody in 60% of patients, and autoantibody to SLA/LP in 15–20%. Juvenile onset type 2 autoimmune hepatitis is associated with LKM-1 and LC-1 autoantibodies. Primary biliary cholangitis is associated with a mitochondria-associated autoantibody designated M2 in >90% of patients and with disease-specific antinuclear autoantibodies in 50% that bind to antigens in the nuclear core complex and in multiple nuclear dots. Autoantibodies to the nuclear core complex target gp210, nucleoporin p62 and nuclear lamin B receptor. Autoantibodies to multiple nuclear dots target Sp100 and PML antigens. Liver autoantibodies in asymptomatic patients with normal liver function may precede the subsequent development of overt autoimmune liver disease. For routine diagnostic immunology laboratories, initial screening for liver autoantibodies by immunofluorescence remains the method of choice with confirmation for reactivity with their target antigen by enzyme-linked immunosorbent assay (ELISA) or line blot when required.

Autoantibodies in Autoimmune Liver Diseases-Methods of Detection and Interpretation: An Update for the Reporting Pathologist

Autoimmune liver disease (AILD) is a type of chronic liver disease with autoimmune etiology. The diagnosis of the disease is multipronged and detection of autoantibodies in AILDs is an important diagnostic tool and it also helps in the classification of the disease. There are multiple autoantibodies that are detected in AILDs but none is diagnostic. Moreover, these autoantibodies are detected in many other pathological and nonpathological conditions. So the significance of seropositivity for these autoantibodies should be known by both the pathologists as well as the clinicians. In addition, there is prognostic significance associated with some of the antibodies and they also sometimes help in the disease monitoring. The whole array of antibodies detected in AILDs is discussed in detail in this review along with their clinical significance and interpretation.

Brazilian society of hepatology recommendations for the diagnosis and management of autoimmune diseases of the liver

ABSTRACT In order to draw evidence-based recommendations concerning the management of autoimmune diseases of the liver, the Brazilian Society of Hepatology has sponsored a single-topic meeting in October 18th, 2014 at São Paulo. An organizing committee comprised of seven investigators was previously elected by the Governing Board to organize the scientific agenda as well as to select twenty panelists to make a systematic review of the literature and to present topics related to the diagnosis and treatment of autoimmune hepatitis, primary sclerosing cholangitis, primary biliary cirrhosis and their overlap syndromes. After the meeting, all panelists gathered together for the discussion of the topics and the elaboration of those recommendations. The text was subsequently submitted for suggestions and approval of all members of the Brazilian Society of Hepatology through its homepage. The present paper is the final version of the reviewed manuscript organized in topics, followed by the recommendations of the Brazilian Society of Hepatology.

Autoimmune Hepatitis in Brazilian Children: IgE and Genetic Polymorphisms in Associated Genes

Pediatric autoimmune hepatitis (AIH) patients present hypergammaglobulinemia, periportal CD8(+) cytotoxic T cell infiltration, and cirrhosis. Autoantibody profile defines AIH types 1 and 2 in addition to strong association with HLA-DRB1. We previously detected increased IgE serum levels and sought to compare clinical and histological features according to IgE levels in AIH (n = 74, ages 1-14 years) patients. Additionally, we typed 117 patients and 227 controls for functional polymorphisms of IL4, IL13, IL5, and IL4RA genes involved in IgE switching and eosinophil maturation that might contribute to overall genetic susceptibility to AIH. Serum IgE levels were high in 55% of AIH-1, but only in 12% of AIH-2 (P = 0.003) patients. Liver IgE was present in 91.3% of AIH-1 patients. The A alleles at both IL13 rs20541 and IL4RA rs1805011 were associated with AIH-1 (P = 0.024, OR = 1.55 and P < 0.0001, OR = 2.15, resp.). Furthermore, individuals presenting homozygosis for the A allele at IL4RA rs1805011 and HLA-DRB1(∗)03 and/or (∗)13 allele had sixfold greater risk to develop the disease (OR = 14.00, P < 0.001). The novel association suggests an additional role for IgE-linked immune response genes in the pathogenesis of AIH.

The clinical phenotypes of autoimmune hepatitis: A comprehensive review

Autoimmune hepatitis (AIH) fulfills the generally accepted contemporary criteria of an autoimmune liver disease: the presence of autoantibodies and autoreactive T cells, a female gender bias, association with other autoimmune diseases, response to immunosuppressive therapy and strong associations with the major histocompatibility complex HLA loci. It occurs worldwide in both children and adults and is marked by both etiopathogenic and clinical heterogeneity, differing from the other putative autoimmune liver diseases, primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC), albeit occasionally presenting with overlapping features of PBC or PSC. Although diagnostic criteria have been established and validated, there are still major issues to be clarified due to its variability, such as autoantibody-negative AIH, drug-induced AIH, AIH sharing features with PBC or PSC, and post-transplant de novo AIH. In view of the diverse presentations and courses, including classical chronic onset, acute and acute severe onset, cirrhosis and decompensated cirrhosis, individualized management of patients is indicated. Each patient should receive a personalized analysis of the benefits and side effect risks of drugs. Herein we describe a comprehensive review of the clinical phenotypes of AIH underscoring its clinical heterogeneity.

Update on Autoimmune Hepatitis

Autoimmune hepatitis (AIH), a liver disorder affecting both children and adults, is characterized by inflammatory liver histology, elevated transaminase levels, circulating nonorganspecific autoantibodies, and increased levels of immunoglobulin G, in the absence of a known etiology. Two types of AIH are recognized according to seropositivity: smooth muscle antibody and/or antinuclear antibody define AIH type 1 and antibodies to liver-kidney microsome type 1 and/or liver cytosol type 1 define AIH type 2. AIH type 1 affects both adults and children, while AIH type 2 is mainly a paediatric disease, though it does occasionally affects young adults. AIH should be considered during the diagnostic workup of any patient with increased liver enzyme levels. AIH is exquisitely responsive to immunosuppressive treatment with prednisolone with or without azathioprine, with symptom free long-term survival for the majority of patients. For those who do not respond to standard treatment, or who are difficult-to-treat, mycophenolate mofetil and, in the absence of a response, calcineurin inhibitors should be tried in addition to steroids. The pathogenesis of AIH is not fully understood, although there is mounting evidence that genetic susceptibility, molecular mimicry and impaired immunoregulatory networks contribute to the initiation and perpetuation of the autoimmune attack. Liver damage is thought to be mediated primarily by CD4 T-cells, although recent studies support the involvement of diverse populations, including Th17 cells. A deeper understanding of the pathogenesis of AIH is likely to contribute to the development of novel treatments, such as the adoptive transfer of autologous expanded antigenspecific regulatory T-cells, which ultimately aim at restoring tolerance to liver-derived antigens.

Diagnostic Performance of an Anti-Actin Autoantibody Binding Enzyme Immunodot Blot in Autoimmune Hepatitis Type 1

BACKGROUND

A serologic hallmark of autoimmune hepatitis (AIH) type 1 are anti-smooth muscle autoantibodies (ASMA) with specificity for filamentous actin (F-actin; AAA (anti-actin antibodies)), traditionally detected by indirect immunofluorescence (IFT) using rat liver, kidney, and stomach tissue sections as substrates. However, IFT is a subjective method requiring an experienced investigator. Therefore, a more objective technique for the detection of AAA may be a helpful diagnostic tool.

METHODS

In a retrospective study with cross-sectional design, we evaluated AAA detected by an enzyme immunodot blot (IDB; Liver5 IgG BlueDot, D-tek, Mons, Belgium). Serum samples of patients with AIH type 1 (n = 47) and specified controls (n = 142) were included. For comparison, standard IFT was applied to rat LKS (liver, kidney, stomach) triple tissue sections.

RESULTS

IDB readings were done by two independent investigators (92% concordance). The diagnostic sensitivity of the AAA-IDB was 70%, compared to 51% of AAA-IFT (n.s.). The diagnostic specificity of AAA-IDB was significantly lower compared to AAA-IFT (76% vs. 94%; P < 0.0005). Correspondingly, the positive predictive value (49% vs. 75%; P < 0.05) and positive likelihood ratio (2.9 vs. 8.5) differed significantly. Neither prescreening for ANA or ASMA, nor the exclusion of infectious hepatopathies resulted in a significantly better diagnostic performance of the IDB.

CONCLUSION

Compared to standard IFT, testing for AAA via IDB did not result in a significantly better diagnostic performance for AIH type 1. A blot with higher antigen binding specificity may be more functional.

Meta-analysis: diagnostic accuracy of antinuclear antibodies, smooth muscle antibodies and antibodies to a soluble liver antigen/liver pancreas in autoimmune hepatitis

Background

Antinuclear antibodies (ANA), smooth muscle antibodies (SMA) and antibodies to a soluble liver antigen/liver pancreas (anti-SLA/LP) are useful markers that can help clinicians to diagnose and classify autoimmune hepatitis (AIH).

Objectives

To determine whether ANA, SMA and anti-SLA/LP help to accurately diagnose patients with AIH.

Search strategy

The PubMed, CNKI, WANFANG, and SinoMed databases were accessed to retrieve studies published in English and Chinese. Studies published up to October 2013 were reviewed.

Selection criteria

Studies on the diagnostic value of ANA, SMA or anti-SLA/LP in the diagnosis of known or suspected AIH were included.

Data collection and analysis

Two authors evaluated studies independently and rated their methodological quality using quality assessment of diagnostic accuracy studies (QUADAS) tools; relevant data were abstracted. The random-effects method was used to summarize sensitivities, specificities, positive and negative likelihood ratios, and diagnostic odds ratios (DORs) from all 29 studies.

Results

The pooled sensitivity, specificity, positive and negative likelihood ratios, and DOR for ANA were 0.650 (95% confidence interval [CI], 0.619 to 0.680), 0.751 (95%CI, 0.737 to 0.764), 3.030 (95%CI, 2.349 to 3.910), 0.464 (95%CI, 0.356 to 0.604), and 7.380 (95%CI, 4.344 to 12.539), respectively. For SMA, the values were 0.593 (95%CI, 0.564 to 0.621), 0.926 (95%CI, 0.917 to 0.934), 11.740 (95%CI, 7.379 to 18.678), 0.449 (95%CI, 0.367 to 0.549), and 31.553 (95%CI, 17.147 to 58.060), respectively. Finally, for anti-SLA/LP, the values were 0.194 (95%CI, 0.168 to 0.222), 0.989 (95%CI, 0.985 to 0.993), 11.089 (95%CI, 7.601 to 16.177), 0.839 (95%CI, 0.777 to 0.905), and 16.867 (95%CI, 10.956 to 25.967), respectively.

Authors’ conclusions

ANA provided moderate sensitivity and specificity, while SMA gave moderate sensitivity and high specificity, and anti-SLA/LP exhibited low sensitivity and high specificity. All three antibodies were limited by their unsatisfactory sensitivities and lack of consistency.

Autoimmune Hepatitis: Clinical Review with Insights into the Purinergic Mechanism of Disease

Autoimmune hepatitis (AIH) is an important disorder that predominantly results in inflammatory liver disease in genetically predisposed women. The clinicopathological picture is characterized by symptoms associated with both systemic inflammation and hepatic dysfunction, and with increased serum aminotransferases, elevated IgG, autoantibodies, and interface hepatitis on liver biopsy. AIH usually results in liver injury as a consequence of chronic hepatitis and cirrhosis. However, rarely, patients may present with fulminant liver failure. Early diagnosis is important in all instances because the disease can be highly responsive to immunosuppressive therapeutic options. Left untreated, the disease is associated with high morbidity and mortality. Here we provide an overview of the current state of knowledge on AIH and summarize the treatment options for this serious condition in adults. We also discuss the pathogenesis of the disease as a possible consequence of autoimmunity and the breakdown of hepatic tolerance. We focus on regulatory T cell impairments as a consequence of changes in CD39 ectonucleotidase expression and altered purinergic signaling. Further understanding of hepatic tolerance may aid in the development of specific and well-tolerated therapies for AIH.

Liver immunology

The liver is the largest organ in the body and is generally regarded by nonimmunologists as having little or no lymphoid function. However, such is far from accurate. This review highlights the importance of the liver as a lymphoid organ. Firstly, we discuss experimental data surrounding the role of liver as a lymphoid organ. The liver facilitates tolerance rather than immunoreactivity, which protects the host from antigenic overload of dietary components and drugs derived from the gut and it is instrumental to fetal immune tolerance. Loss of liver tolerance leads to autoaggressive phenomena, which if not controlled by regulatory lymphoid populations, may lead to the induction of autoimmune liver diseases. Liver-related lymphoid subpopulations also act as critical antigen-presenting cells. The study of the immunological properties of liver and delineation of the microenvironment of the intrahepatic milieu in normal and diseased livers provides a platform to understand the hierarchy of a series of detrimental events that lead to immune-mediated destruction of the liver and the rejection of liver allografts. The majority of emphasis within this review will be on the normal mononuclear cell composition of the liver. However, within this context, we will discuss selected, but not all, immune-mediated liver disease and attempt to place these data in the context of human autoimmunity.

Autoimmune hepatitis as a unique form of an autoimmune liver disease: immunological aspects and clinical overview

Autoimmune hepatitis (AIH) is a unique form of immune-mediated disease that attacks the liver through a variety of immune mechanisms. The outcomes of AIH are either acute liver disease, which can be fatal, or, more commonly, chronic progressive liver disease, which can lead to decompensated liver cirrhosis if left untreated. AIH has characteristic immunological, and pathological, features that are important for the establishment of the diagnosis. More importantly, most patients with AIH have a favorable response to treatment with prednisolone and azathioprine, although some patients with refractory AIH or more aggressive disease require more potent immune-suppressant agents, such as cyclosporine or Mycophenolate Mofetil. In this paper, we discuss the immunological, pathological and clinical features of AIH, as well as the standard and alternative treatments for AIH.

Longitudinal study of a human drug-induced model of autoantibody to cytoplasmic rods/rings following HCV therapy with ribavirin and interferon-α

Background

A novel pattern in the indirect immunofluorescence antinuclear antibody assay on HEp-2 cells (IIF-HEp-2) characterized by cytoplasmic rods and rings (RR) was reported in HCV patients, but stringent disease specificity studies and longitudinal analysis are lacking. We investigated the clinical significance of anti-RR in an HCV cohort with up to a 12-month treatment follow up.

Methodology/Results

597 patients (342 HCV, 55 HCV/HIV, 200 non-HCV) were screened and titered for anti-RR. Serial samples were available from 78 of 176 treated and 27 of 166 untreated patients. Anti-RR was detected in 14.1% of 342 HCV patients, 9.1% of 55 HCV/HIV, 3.4% of 29 Hepatitis B, and none of 171 non-HCV (p<0.0001; HCV versus non-HCV). Anti-RR was present in 38% of 108 patients receiving interferon-α/ribavirin, but none in 26 receiving either interferon-α or ribavirin, or 166 untreated patients (p<0.0001). Other IIF-HEp-2 patterns were more frequently associated with interferon-α treatment alone (52.2%) as compared to interferon-α/ribavirin (25%), ribavirin alone (33.3%), and no therapy (26.5%). Anti-RR frequency was not associated with sex, age, ethnicity, HCV genotype or viral load. Anti-RR occurred only after initiation of treatment, beginning as early as 1 month (6%), but by the sixth month >47% tested positive for anti-RR. The anti-RR titer generally increased with sustained treatment and remained high in 53% of patients. After treatment, anti-RR titer was negative in 41%. Non-responders to HCV therapy were 77% in anti-RR-positive versus 64% in anti-RR-negative patients. Response to treatment was not associated with anti-RR titer or the dynamics of anti-RR reactivity during and after treatment.

Conclusions

The exquisite association of anti-RR reactivity with combined interferon-α/ribavirin therapy in HCV patients represents a unique model for drug-induced autoantibody generation in humans as demonstrated by the fact that a significant fraction of patients who have anti-RR during therapy becomes anti-RR-negative after completion of therapy.

Cutting edge issues in autoimmune hepatitis

Autoimmune hepatitis is an inflammatory liver disease affecting mainly females and characterised histologically by interface hepatitis, biochemically by elevated transaminase levels and serologically by circulating autoantibodies and increased levels of immunoglobulin G. Autoimmune hepatitis responds to immunosuppressive treatment, which should be instituted as soon as diagnosis is made. Seropositivity for smooth muscle and/or antinuclear antibody defines type 1 autoimmune hepatitis, while positivity for liver kidney microsomal type 1 antibody defines type 2 autoimmune hepatitis. The aetiology of autoimmune hepatitis is unknown, though both genetic and environmental factors are involved in its expression. The major mechanism of liver damage involves immune reactions against host liver antigens that are not adequately controlled by defective regulatory T cells. Current research aiming at potentiating regulatory T cell function in vitro to reconstitute tolerance in vivo has given promising results.

Autoimmune manifestations in viral hepatitis

Infections by the viruses responsible for hepatitis B, C and D are accompanied by a number of immunopathological manifestations. A link between infection and autoimmunity is particularly well documented for the hepatitis C virus. Immunopathological manifestations range from production of autoantibodies to overt autoimmune disease, including thyroiditis and autoimmune hepatitis, and to immune-complex-mediated disorders, including cryoglobulinaemia, glomerulonephritis and vasculitis. Several of these manifestations improve with successful antiviral treatment, directly incriminating the virus in their pathogenesis. Mechanisms considered responsible for hepatitis virus-related immunopathology, including molecular mimicry, impairment of regulatory T cells and activation of B lymphocytes, will be examined in this review.

Autoimmune hepatitis

Autoimmune hepatitis (AIH) is an inflammatory liver disease that mainly affects females. It is characterized histologically by interface hepatitis, biochemically by increased aspartate and alanine aminotransferase levels, and serologically by the presence of autoantibodies and increased levels of immunoglobulin G. AIH affects both adults and children, and is particularly aggressive in the latter group. It is a relatively rare but devastating disease, which progresses rapidly unless immunosuppressive treatment is started promptly. With appropriate treatment 80% of patients achieve remission and long-term survival. Those patients who progress to end-stage liver disease because they are unresponsive or nonadherent to treatment, and those with fulminant liver failure (encephalopathy grade II-IV) at diagnosis, require liver transplantation. Seropositivity for smooth muscle and/or antinuclear antibodies defines type 1 AIH, while positivity for liver kidney microsomal type 1 antibodies defines type 2 AIH. The primary cause of AIH is unknown; however, considerable knowledge about the mechanisms of liver damage involved has been gathered over the past 30 years, which is likely to provide the basis for specific modes of treatment and a possible cure.

A 50-year experience with autoimmune hepatitis: and where are we now?

BACKGROUND

Autoimmune hepatitis (AIH) as chronic active hepatitis became recognized in the 1940s as a progressive hyperglobulinemic disease affecting younger women attributed to persisting virus infection of the liver: autoimmunity then was barely on the horizon.

EARLY OBSERVATIONS

The lupus erythematosus (LE) cell reported in 1948 signified the presence of antinuclear autoantibodies, promoting perceptions of autoimmunity in certain chronic diseases. Recognition of LE cells in chronic hepatitis led to the designation of 'lupoid hepatitis', with autoimmunity further substantiated by anti-cytoplasmic autoantibodies detected by complement fixation. Next a serum reactant with smooth muscle of rodent stomach was found to have a wider distribution and became identified as an autoantibody to filamentous (F) actin. Therapy with corticosteroids proved effective, particularly combined with azathioprine. Various trials showed greatly improved survival and established modern therapy of AIH. An HLA-based predisposition (B8, DR3) was the first pointer to a genetic etiology.

RECENT ADVANCES

Recombinant or purified autoantigenic substrates have led to automated assays, which, together with improved immunofluorescence procedures, allow serological confidence in diagnosis and institution of effective immunosuppressive therapies. The liver-kidney 'microsomal' autoantigen reactive with cytochrome P450 2D6 distinguishes two serological types of AIH that appear pathogenetically distinct. Molecular characterization of antigens and epitopes remains wanting in type 1 AIH.

FUTURE PROSPECTS

The challenge remains with both types of AIH to elucidate in molecular terms the genetic and environmental basis of pathogenesis from initiation to ultimate progression and cirrhosis (when inadequately treated). Advancing technologies are bringing this goal closer to being attainable.

Current topics in autoimmune hepatitis

Autoimmune hepatitis is a chronic liver disease of unknown aetiology characterized by interface hepatitis, hypergammaglobulinaemia and circulating autoantibodies. In the last decade a number of advancements have been made in the field of clinical and basic research: the simplified diagnostic criteria, the complete response defined as normalization of transaminase levels, the molecular identification of the antigenic targets of anti-liver cytosol antibody type 1 and anti-soluble liver antigen, the detection of anti-actin antibodies, the description of de novo autoimmune hepatitis after liver transplantation for non-autoimmune liver diseases, the characterization of autoimmune hepatitis with overlapping features of primary biliary cirrhosis or primary sclerosing cholangitis, the preliminary experience with novel treatment strategies based on cyclosporine, mycophenolate mofetil and budesonide, the role played by "impaired" regulatory T cells and the development of novel animal models of autoimmune hepatitis.

Autoantibodies as prognostic markers in autoimmune liver disease

Certain autoantibodies in autoimmune liver disease have prognostic implications that are under-utilized and under-developed. The goals of this review are to indicate progress in characterizing the autoantibodies with prognostic connotations and to indicate the feasibility and importance of discovering other markers. Prime source and review articles in English were selected by a Medline search through 2010. Antibodies to soluble liver antigen, actin, liver cytosol type 1, asialoglycoprotein receptor, chromatin, cyclic citrullinated peptide, and uridine glucuronosyltransferases have been associated with the occurrence, severity, and progression of autoimmune hepatitis, and antibodies to Sp100, gp210, and centromere have had similar implications in primary biliary cirrhosis. Antibodies to soluble liver antigen have shown the most promise in autoimmune hepatitis as they have been associated with severe histological changes, long durations of treatment, relapse after drug withdrawal, and high frequency of liver failure. Antibodies to the nuclear rim pore protein, gp210, have shown the most promise in primary biliary cirrhosis as they have been associated with severe interface hepatitis, lobular inflammation, and progression to liver failure. The major limitations of the autoantibodies have been their lack of standardized assays, low negative predictabilities, and fluctuating levels. Performance parameters will improve as critical pathogenic pathways, comprehensive testing batteries, and standardized assays through international exchange workshops are developed. Progress has been made in identifying the serological markers of prognosis in autoimmune liver disease, and they promise to reflect critical disease mechanisms and enhance patient management.

Clinical and biologic importance of F-actin autoantibodies in HCV monoinfected and HCV-HIV coinfected patients

The purpose of this study was to evaluate the relationship between serum filamentous (F)-actin antibody titers and severity of hepatitis present in hepatitis C virus (HCV)-infected patients. Liver biopsy samples from 18 HCV monoinfected and 20 HCV-HIV coinfected patients were graded with respect to the degree of hepatitis activity and intensity of plasma cell infiltration using MUM-1 and CD138 immunostains. Of the 38 HCV-infected patients, 6 (16%) had F-actin antibody titers in excess of 30 enzyme-linked immunosorbent assay units. We found a positive trend between serum F-actin antibody levels and the mean number of plasma cells present in the portal tracts of patients with HCV infection (r = 0.31; P = .06) and a significant association between these factors in HCV-HIV coinfected patients (r = 0.64; P = .002). Our data suggest that elevated serum F-actin antibody titers are commonly encountered in HCV-infected patients and may reflect more active inflammation in liver biopsy samples, similar to autoimmune hepatitis.

Advances in the diagnosis, pathogenesis, and management of autoimmune hepatitis

Autoimmune hepatitis (AIH) is characterized by chronic inflammation of the liver, interface hepatitis (based on histologic examination), hypergammaglobulinemia, and production of autoantibodies. Many clinical and basic science studies have provided important insights into the pathogenesis and treatment of AIH. Transgenic mice that express human antigens and develop autoantibodies, liver-infiltrating CD4(+) T cells, liver inflammation, and fibrosis have been developed as models of AIH. AIH has been associated with autoantibodies against members of the cytochrome P450 superfamily of enzymes, transfer RNA selenocysteine synthase, formiminotransferase cyclodeaminase, and the uridine diphosphate glucuronosyltransferases, whereas alleles such as DRB1*0301 and DRB1*0401 are genetic risk factors in white North American and northern European populations. Deficiencies in the number and function of CD4(+)CD25(+) (regulatory) T cells disrupt immune homeostasis and might be corrected as a therapeutic strategy. Treatment can be improved by continuing corticosteroid therapy until normal liver test results and normal liver tissue are within normal limits, instituting ancillary therapies to prevent drug-related side effects, identifying problematic patients early, and providing long-term maintenance therapy after patients experience a first relapse. Calcineurin inhibitors and mycophenolate mofetil are potential salvage therapies, and reagents such as recombinant interleukin-10, abatacept, and CD3-specific antibodies are feasible as therapeutics. Liver transplantation is an effective salvage therapy, even in the elderly, and AIH must be considered in all patients with graft dysfunction after liver transplantation. Identification of the key defects in immune homeostasis and antigen targets will direct new therapies.

F-actin reactive smooth muscle antibody in subjects with normal liver function

AIMS

Smooth muscle antibody (SMA) with F-actin reactivity has been reported as a diagnostic marker of autoimmune hepatitis. We re-visited this relationship by randomly selecting SMA-positive sera to test for reactivity with F-actin by ELISA. We correlated such reactivity with liver function tests.

METHODS

Sera positive for SMA by indirect immunofluorescence were tested for reactivity by F-actin ELISA and the results correlated with liver function tests.

RESULTS

89 SMA-positive sera reacted with F-actin by ELISA. Of these, 35 (39%) had normal liver enzymes, while 54 (60%) had elevated liver enzymes. There was no difference between the groups with respect to age at presentation, female preponderance or presence of anti-nuclear antibody. In both groups, high titre SMA antibody predominantly with immunofluorescence staining of renal glomeruli and peritubular fibrils of renal tubules ('G/T' subset) correlated with makedly elevated F-actin values by ELISA. 'Actin cables' by immunofluorescence staining of Hep-2 cells were infrequently found in both groups.

CONCLUSIONS

This is the first report of SMA with F-actin reactivity in subjects with normal liver function.

Autoimmune hepatitis

Autoimmune hepatitis (AIH) is an inflammatory liver disease affecting mainly females and characterised histologically by interface hepatitis, biochemically by elevated transaminase levels and serologically by the presence of autoantibodies and increased levels of immunoglobulin G. AIH responds to immunosuppressive treatment, which should be instituted as soon as diagnosis is made. Seropositivity for smooth muscle and/or anti-nuclear antibody defines type 1 AIH, while positivity for liver kidney microsomal type 1 antibody defines type 2 AIH. The aetiology of AIH is unknown, though both genetic and environmental factors are involved in its expression. Immune reactions against host liver antigens are believed to be the major mechanism of liver damage.

Smooth muscle autoantibodies with F-actin specificity

Autoimmune hepatitis is a rare condition characterized by the presence of autoantibodies, among other features. Anti-smooth muscle autoantibodies with F-actin reactivity have long been considered specific markers of this disease, representing a valuable diagnostic element because they are distinctive of a subtype of autoimmune hepatitis: type 1. Indirect immunofluorescence is considered the best available method for detection of these autoantibodies, mainly because of its elevated sensibility, but it has some flaws: it is highly operator-dependent, and the standardization of the technique has not been achieved until now. We compared ELISA and Immunodot methods for confirming indirect immunofluorescence results in what concerns smooth-muscle autoantibodies' F-actin reactivity and concluded that ELISA is the most useful one. A new substrate is available for indirect immunofluorescence detection of anti-F-actin specificity, and seems to be a promising one, but further evaluation is needed.

An actin-myosin functional assay for analysis of smooth muscle (anti-microfilament) autoantibodies in human plasma

The detection of serum autoantibodies to smooth muscle (SMA) on rodent gastric mucosa by indirect immunofluorescence (IIF) has long been an immunodiagnostic marker for autoimmune hepatitis type 1 (AIH-1). The reactive antigenic moieties are cytoskeletal proteins which include polymeric F-actin as judged by the staining of microfilaments of tissue by IIF. However, their specificity for actin in AIH-1 can be and usually is uncertain. Using an in vitro functional assay, we compared the effects of Fab fragments of immunoglobulin (IgG) prepared from SMA-positive plasma from two patients with the effects of Fabs from 10 healthy subjects. Fabs are incorporated into an assay where actin (the putative antigen) activates skeletal muscle heavy meromyosin (HMM) ATPase activity. The data from these functional assays provide new insights into the significance of anti-microfilament assays in the diagnosis, and perhaps also pathogenesis, of AIH-1.

Autoimmune paediatric liver disease

Liver disorders with a likely autoimmune pathogenesis in childhood include autoimmune hepatitis (AIH), autoimmune sclerosing cholangitis (ASC), and de novo AIH after liver transplantation. AIH is divided into two subtypes according to seropositivity for smooth muscle and/or antinuclear antibody (SMA/ANA, type 1) or liver kidney microsomal antibody (LKM1, type 2). There is a female predominance in both. LKM1 positive patients tend to present more acutely, at a younger age, and commonly have partial IgA deficiency, while duration of symptoms before diagnosis, clinical signs, family history of autoimmunity, presence of associated autoimmune disorders, response to treatment, and long-term prognosis are similar in both groups. The most common type of paediatric sclerosing cholangitis is ASC. The clinical, biochemical, immunological, and histological presentation of ASC is often indistinguishable from that of AIH type 1. In both, there are high IgG, non-organ specific autoantibodies, and interface hepatitis. Diagnosis is made by cholangiography. Children with ASC respond to immunosuppression satisfactorily and similarly to AIH in respect to remission and relapse rates, times to normalization of biochemical parameters, and decreased inflammatory activity on follow up liver biopsies. However, the cholangiopathy can progress. There may be evolution from AIH to ASC over the years, despite treatment. De novo AIH after liver transplantation affects patients not transplanted for autoimmune disorders and is strikingly reminiscent of classical AIH, including elevated titres of serum antibodies, hypergammaglobulinaemia, and histological findings of interface hepatitis, bridging fibrosis, and collapse. Like classical AIH, it responds to treatment with prednisolone and azathioprine. De novo AIH post liver transplantation may derive from interference by calcineurin inhibitors with the intrathymic physiological mechanisms of T-cell maturation and selection. Whether this condition is a distinct entity or a form of atypical rejection in individuals susceptible to the development of autoimmune phenomena is unclear. Whatever its etiology, the recognition of this potentially life-threatening syndrome is important since its management differs from that of standard anti-rejection therapy.

Historical reflections on autoimmune hepatitis

Autoimmune hepatitis (AIH), initially known as chronic active or active chronic hepatitis (and by various other names), first came under clinical notice in the late 1940s. However, quite likely, chronic active hepatitis (CAH) had been observed prior to this and was attributed to a persistently destructive virus infection of the liver. An earlier (and controversial) designation in 1956 as lupoid hepatitis was derived from associated L.E. cell test positivity and emphasized accompanying multisystem features and immunological aberrations. Young women featured prominently in early descriptions of CAH. AIH was first applied in 1965 as a descriptive term. Disease-characteristic autoantibodies were defined from the early 1960s, notably antinuclear antibody (ANA), smooth muscle antibody (SMA) and liver-kidney microsomal (LKM) antibody. These are still widely used diagnostically but their relationship to pathogenesis is still not evident. A liver and disease specific autoantigen has long been searched for but unsuccessfully. Prolonged immunosuppressive therapy with predisolone and azathioprine in the 1960s proved beneficial and remains standard therapy today. AIH like many other autoimmune diseases is associated with particular HLA alleles especially with the "ancestral" B8, DR3 haplotype, and also with DR4. Looking forwards, AIH is one of the several enigmatic autoimmune diseases that, despite being (relatively) organ specific, are marked by autoimmune reactivities with non-organ-specific autoantigens. New paradigms are needed to explain the occurrence, expressions and pathogenesis of such diseases.

Autoimmune liver serology: Current diagnostic and clinical challenges

Liver-related autoantibodies are crucial for the correct diagnosis and classification of autoimmune liver diseases (AiLD), namely autoimmune hepatitis types 1 and 2 (AIH-1 and 2), primary biliary cirrhosis (PBC), and the sclerosing cholangitis variants in adults and children. AIH-1 is specified by anti-nuclear antibody (ANA) and smooth muscle antibody (SMA). AIH-2 is specified by antibody to liver kidney microsomal antigen type-1 (anti-LKM1) and anti-liver cytosol type 1 (anti-LC1). SMA, ANA and anti-LKM antibodies can be present in de-novo AIH following liver transplantation. PBC is specified by antimitochondrial antibodies (AMA) reacting with enzymes of the 2-oxo-acid dehydrogenase complexes (chiefly pyruvate dehydrogenase complex E2 subunit) and disease-specific ANA mainly reacting with nuclear pore gp210 and nuclear body sp100. Sclerosing cholangitis presents as at least two variants, first the classical primary sclerosing cholangitis (PSC) mostly affecting adult men wherein the only (and non-specific) reactivity is an atypical perinuclear antineutrophil cytoplasmic antibody (p-ANCA), also termed perinuclear anti-neutrophil nuclear antibodies (p-ANNA) and second the childhood disease called autoimmune sclerosing cholangitis (ASC) with serological features resembling those of type 1 AIH. Liver diagnostic serology is a fast-expanding area of investigation as new purified and recombinant autoantigens, and automated technologies such as ELISAs and bead assays, become available to complement (or even compete with) traditional immunofluorescence procedures. We survey for the first time global trends in quality assurance impacting as it does on (1) manufacturers/purveyors of kits and reagents, (2) diagnostic service laboratories that fulfill clinicians’ requirements, and (3) the end-user, the physician providing patient care, who must properly interpret test results in the overall clinical context.

Diagnostic accuracy of four different immunological methods for the detection of anti-F-actin autoantibodies in type 1 autoimmune hepatitis and other liver-related disorders

BACKGROUND

Smooth muscle antibodies (SMA) with anti-F-actin specificity are commonly regarded as specific markers of type 1 autoimmune hepatitis (AIH-1) but, at the moment, a gold standard method for their identification is not available.

OBJECTIVES

To evaluate the diagnostic accuracy for AIH-1 of three new methods of detecting anti-F-actin antibodies, and to compare the results with those obtained using the indirect immunofluorescence (IIF) method on rodent tissue.

METHODS

The sera of 33 AIH-1 patients and 104 controls (eight with type 2 AIH, 30 with chronic hepatitis C, 16 with celiac disease, 40 with primary biliary cirrhosis, and 10 with liver steatosis) were assayed for anti-F-actin antibodies using four methods: two IIF methods (one on rat tissue sections and the other on VSM 47 cell line derived from the thoracic aorta of rat embryo), an ELISA method and an Immunodot (ID) method.

RESULTS

The diagnostic sensitivity, specificity, positive predictive value and negative predictive value were, respectively, 51.5, 95.2, 77.3 and 86.1% for IIF on the VSM 47 cell line; 63.6, 86.5, 60 and 88.2% for the ELISA method; 72.7, 82.7, 57.1 and 90.5% for the ID assay; and 57.6, 96.1, 82.6 and 87.7% for the IIF on rat tissue sections.

CONCLUSION

The methods used for anti-F-actin antibody detection have different diagnostic performances. Both IIF methods, the one on rat tissues and the other on VSM47 cell line, are highly specific for AIH-1. In contrast, ELISA and especially ID show positive results in control population, although usually at low levels (with the single exception of PBC patients). Therefore, having a high positive predictive value, both IIF methods are reliable tools for the specific detection of AIH-associated anti-F-actin autoantibodies, whereas the immunometric assays might be integrated into the diagnostic scheme as second level tests upon improvement of their respective cut-offs to confirm anti-F-actin positivity in case of SMA positivity.