Clinical significance of autoantibodies in autoimmune hepatitis

The accurate diagnosis and classification of autoimmune hepatitis (AIH) rely upon the detection of characteristic autoantibodies. Positivity for anti-nuclear (ANA) and/or anti-smooth muscle (SMA) autoantibodies defines AIH type 1 (AIH-1), whereas anti-liver kidney microsomal type 1 (anti-LKM1) and/or anti-liver cytosol type 1 (anti-LC1) define AIH type 2 (AIH-2). ANA and SMA, and less commonly anti-LKM1, have also been detected in de-novo autoimmune hepatitis developing after liver transplantation, a condition that may affect patients transplanted for non-autoimmune liver disease. The diagnostic autoantibodies associated with AIH-1 are also detected in the paediatric AIH/sclerosing cholangitis overlap syndrome, referred to as autoimmune sclerosing cholangitis (ASC). ASC, like adult primary sclerosing cholangitis, is often associated with atypical perinuclear anti-neutrophil cytoplasmic autoantibodies (p-ANCA), although p-ANCA are also detected in other autoimmune liver diseases. These associations highlight the necessity for simple and prompt diagnostic autoantibody testing, and the requirement for the accurate interpretation of the results of the tests in the clinical context. Fine-mapping of antigenic autoantibody targets has facilitated the development of rapid molecular assays that have the potential to revolutionise the field if properly standardised and when used in combination with classical immunofluorescence. Despite their diagnostic significance, the pathogenic role of the various autoantibodies and the mechanisms by which they can potentially inflict damage onto the liver cell remain a topic for further research.     

Autoimmmune hepatitis

Autoimmune hepatitis (AIH) is a T-cell mediated, inflammatory liver disease affecting all ages and characterized by female preponderance, elevated serum transaminase and immunoglobulin G levels, positive circulating autoantibodies, and presence of interface hepatitis at liver histology. AIH type 1, affecting both adults and children, is defined by positive anti-nuclear and/or anti-smooth muscle antibodies, while type 2 AIH, affecting mostly children, is defined by positive anti-liver-kidney microsomal type 1 and/or anti-liver cytosol type 1 antibody. While the autoantigens of type 2 AIH are well defined, being the cytochrome P4502D6 (CYP2D6) and the formiminotransferase cyclodeaminase (FTCD), in type 1 AIH they remain to be identified. AIH-1 predisposition is conferred by possession of the MHC class II HLA DRB1*03 at all ages, while DRB1*04 predisposes to late onset disease; AIH-2 is associated with possession of DRB1*07 and DRB1*03. The majority of patients responds well to standard immunosuppressive treatment, based on steroid and azathioprine; second- and third-line drugs should be considered in case of intolerance or insufficient response. This review offers a comprehensive overview of pathophysiological and clinical aspects of AIH.     

The hepatitic/cholestatic "overlap" syndrome: an Italian experience

BACKGROUND: Patients with hepatitic and cholestatic autoimmune liver disease ("overlap syndrome") represent a diagnostic and therapeutic challenge. AIM: To evaluate the prevalence of the "hepatitic/cholestatic overlap" in a large series of consecutive patients with cholestatic autoimmune liver disease. METHODS: We re-evaluated the diagnosis of 235 patients with autoimmune liver disease, including 70 with type 1 autoimmune hepatitis (AIH), 142 with primary biliary cirrhosis (PBC), and 23 with primary sclerosing cholangitis (PSC), using the revised International Autoimmune Hepatitis Group (IAIHG) scoring system. Anti-mitochondrial, anti-nuclear, anti-smooth muscle, anti-liver kidney microsomal type 1, anti-liver cytosol type 1, perinuclear anti-neutrophil nuclear and anti-soluble liver antigen antibodies were evaluated in each patient. RESULTS: Ten patients (3 with a previous diagnosis of PBC and 7 of PSC) scored as "probable" or "definite" AIH. These patients did not have a specific autoantibody profile. CONCLUSIONS: Among patients with PBC, the occurrence of a PBC/AIH overlapping syndrome is rare (2.1%), whereas among patients with PSC an overlap between PSC and AIH is frequent (30.4%). Whether patients with the hepatitic/cholestatic overlap syndrome would benefit from a combination therapy with immunosuppression and ursodeoxycholic acid remains to be established.     

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.     

The Hepatitic/Cholestatic "Overlap" Syndrome: An Italian Experience

Background: Patients with hepatitic and cholestatic autoimmune liver disease ("overlap syndrome") represent a diagnostic and therapeutic challenge. Aim: To evaluate the prevalence of the "hepatitic/cholestatic overlap" in a large series of consecutive patients with cholestatic autoimmune liver disease. Methods: We re-evaluated the diagnosis of 235 patients with autoimmune liver disease, including 70 with type 1 autoimmune hepatitis (AIH), 142 with primary biliary cirrhosis (PBC), and 23 with primary sclerosing cholangitis (PSC), using the revised International Autoimmune Hepatitis Group (IAIHG) scoring system. Anti-mitochondrial, anti-nuclear, anti-smooth muscle, anti-liver kidney microsomal type 1, anti-liver cytosol type 1, perinuclear anti-neutrophil nuclear and anti-soluble liver antigen antibodies were evaluated in each patient. Results: Ten patients (3 with a previous diagnosis of PBC and 7 of PSC) scored as "probable" or "definite" AIH. These patients did not have a specific autoantibody profile. Conclusions: Among patients with PBC, the occurrence of a PBC/AIH overlapping syndrome is rare (2.1%), whereas among patients with PSC an overlap between PSC and AIH is frequent (30.4%). Whether patients with the hepatitic/cholestatic overlap syndrome would benefit from a combination therapy with immunosuppression and ursodeoxycholic acid remains to be established.     

Organ and non-organ specific autoantibody titres and IgG levels as markers of disease activity: a longitudinal study in childhood autoimmune liver disease

No longitudinal study has investigated whether autoantibody titres and serum IgG levels correlate with disease activity in autoimmune liver disease. To determine this, we investigated prospectively 19 patients on 254 occasions between 10 months to 5 years from diagnosis. Nine had anti-nuclear and/or anti-smooth muscle antibody (ANA/SMA) positive autoimmune hepatitis (type 1 AIH), 5 liver kidney microsomal type 1 (LKM-1) positive AIH (type 2 AIH) and 5 ANA/SMA positive autoimmune sclerosing cholangitis (ASC). Correlation between IgG levels, titres of ANA, SMA and LKM-1 and levels of the organ specific autoantibodies anti-liver specific protein (anti-LSP), and anti-asialoglycoprotein receptor (anti-ASGPR) with biochemical evidence of disease activity, as measured by serum aspartate amino transferase (AST) levels, was sought during the course of the disease. AST levels correlated with levels of anti-LSP, anti-ASGPR and IgG in type 1 and 2 AIH, but not in ASC. Positive correlation with AST was also observed for LKM-1 titres in type 2 AIH and for SMA titres in type 1 AIH, but not in ASC. In both AIH and ASC, AST levels correlated with the T cell-dependent immune responses anti rubella IgG and anti tetanus toxoid IgG, but not with the T cell-independent IgG2 response to pneumococcal capsular polysaccaride. Our results indicate that measurement of organ and non-organ specific autoantibodies and IgG levels may be used to monitor disease activity in AIH.     

Organ and Non-organ Specific Autoantibody Titres and IgG Levels as Markers of Disease Activity: A Longitudinal Study in Childhood Autoimmune Liver Disease

No longitudinal study has investigated whether autoantibody titres and serum IgG levels correlate with disease activity in autoimmune liver disease. To determine this, we investigated prospectively 19 patients on 254 occasions between 10 months to 5 years from diagnosis. Nine had anti-nuclear and/or anti-smooth muscle antibody (ANA/SMA) positive autoimmune hepatitis (type 1 AIH), 5 liver kidney microsomal type 1 (LKM-1) positive AIH (type 2 AIH) and 5 ANA/SMA positive autoimmune sclerosing cholangitis (ASC). Correlation between IgG levels, titres of ANA, SMA and LKM-1 and levels of the organ specific autoantibodies anti-liver specific protein (anti-LSP), and anti-asialoglycoprotein receptor (anti-ASGPR) with biochemical evidence of disease activity, as measured by serum aspartate amino transferase (AST) levels, was sought during the course of the disease. AST levels correlated with levels of anti-LSP, anti-ASGPR and IgG in type 1 and 2 AIH, but not in ASC. Positive correlation with AST was also observed for LKM-1 titres in type 2 AIH and for SMA titres in type 1 AIH, but not in ASC. In both AIH and ASC, AST levels correlated with the T cell-dependent immune responses anti rubella IgG and anti tetanus toxoid IgG, but not with the T cell-independent IgG 2 response to pneumococcal capsular polysaccaride. Our results indicate that measurement of organ and non-organ specific autoantibodies and IgG levels may be used to monitor disease activity in AIH.     

Prevalence of non-organ-specific autoantibodies in a rural community from northeastern Brazil: a population-based study

Non-organ-specific autoantibodies (NOSA) are well-recognized diagnostic markers of autoimmune hepatitis (AIH) and primary biliary cirrhosis (PBC), but can also be observed in patients with viral hepatitis as well as in healthy subjects. The aim of this study was to evaluate the prevalence of NOSA in subjects living in a rural community in Brazil and to correlate their occurrence with the presence of liver disease. Seven hundred twenty-five apparently healthy subjects were randomly selected for assessment of antinuclear (ANA), anti-smooth muscle (SMA), antimitochondrial (AMA), anti-liver/kidney microsome type 1, and anti-liver cytosol type 1 antibodies. Subjects with those NOSA were evaluated for the presence of AIH, PBC, and viral hepatitis. Reactivities for all NOSA, SMA, ANA, and AMA were detected, respectively, in 14, 10, 4, and 0.1% of subjects, with a mean titer of 1:40. NOSA-positive subjects were significantly older and more frequently females. No correlation was observed between the occurrence of NOSA and PBC, AIH, or viral hepatitis. The prevalence of NOSA in Brazilians was 14%. They were usually low titer. NOSA were more frequently observed in females and older subjects and their presence was not correlated with the presence of AIH, PBC, or viral hepatitis.     

Do Autoantibodies Predict Autoimmune Liver Disease in Primary Sjögren's Syndrome? Data of 180 Patients upon a 5 Year Follow‐Up

Objective: To evaluate the clinical value of autoantibodies as serological markers to predict autoimmune liver diseases in primary Sjögren's syndrome (SS). Materials and methods: 180 patients who met the European diagnostic criteria for SS but without a history of liver disease were studied upon a 5 year follow‐up. Sera taken at enrolment were evaluated by immunofluorescence analysis (IF‐AMA) on rat liver, stomach and kidney sections, enzyme‐linked immunosorbent assay using rat mitochondrial, microsomal and soluble liver antigens and Western blot (WB) analysis using rat mitochondrial antigens. Results: At presentation, 152 (84%) sera had autoantibodies. Antinuclear antibodies (ANA) were expressed in 58% of patients and displayed three distinct patterns (speckled, homogenous and anticentromere). Smooth muscle autoantibodies (SMAs) and parietal cell autoantibodies were found in 39 and 4.5% of patients, respectively. Three patients presented antimitochondrial antibodies by IF‐AMA, and two of them developed symptomatic primary biliary cirrhosis (PBC). Two patients without IF‐AMA and without evidence of cholestasis had PBC‐specific AMA (anti‐PDC–E2 and anti‐BCKADC–E2). However, these two patients and the third IF‐AMA‐positive woman remained free from symptoms and biochemical signs of PBC. Autoimmune hepatitis (AIH) (n = 2), ‘overlap syndrome’ of AIH and chronic hepatitis C (n = 1) and autoimmune cholangiopathy (AIC) (n = 1) were diagnosed in four patients. Conclusions: Patients with IF‐AMA usually develop symptomatic PBC upon a 5 year follow‐up. Our findings support the idea that patients without IF‐AMA, who express PBC‐specific AMA, are in early, asymptomatic stage of the disease. High‐titre SMA and IF‐AMA are the most specific indicators for AIH and PBC.     

Epitope spreading of the anti-CYP2D6 antibody response in patients with autoimmune hepatitis and in the CYP2D6 mouse model

Autoimmune hepatitis (AIH) is a serious chronic inflammatory disease of the liver with yet unknown etiology and largely uncertain immunopathology. The hallmark of type 2 AIH is the generation of liver kidney microsomal-1 (LKM-1) autoantibodies, which predominantly react to cytochrome P450 2D6 (CYP2D6). The identification of disease initiating factors has been hampered in the past, since antibody epitope mapping was mostly performed using serum samples collected late during disease resulting in the identification of immunodominant epitopes not necessarily representing those involved in disease initiation. In order to identify possible environmental triggers for AIH, we analyzed for the first time the spreading of the anti-CYP2D6 antibody response over a prolonged period of time in AIH patients and in the CYP2D6 mouse model, in which mice infected with Adenovirus-human CYP2D6 (Ad-h2D6) develop antibodies with a similar specificity than AIH patients. Epitope spreading was analyzed in six AIH-2-patients and in the CYP2D6 mouse model using SPOTs membranes containing peptides covering the entire CYP2D6 protein. Despite of a considerable variation, both mice and AIH patients largely focus their humoral immune response on an immunodominant epitope early after infection (mice) or diagnosis (patients). The CYP2D6 mouse model revealed that epitope spreading is initiated at the immunodominant epitope and later expands to neighboring and remote regions. Sequence homologies to human pathogens have been detected for all identified epitopes. Our study demonstrates that epitope spreading does indeed occur during the pathogenesis of AIH and supports the concept of molecular mimicry as a possible initiating mechanism for AIH.     

Current status of autoimmune hepatitis in Japan

Autoimmune hepatitis (AIH) is a chronic and progressive disease characterized by histological interface hepatitis, hypergammaglobulinemia, and circulating autoantibodies. Multiple factors, including molecular mimicry, a genetic background including major histocompatibility complex class II, and defective function of regulatory T-cells, are involved in the pathogenesis. The diagnosis is made based on the scoring system of the International Autoimmune Hepatitis Group, the sensitivity and specificity of which are > 90%, respectively. AIH is classified into 3 sub-types based on the profiles of circulating autoantibodies: anti-nuclear antibody and/or smooth muscle antibody-positive (type 1), anti-liver-kidney microsomal antibody-positive (type 2), and anti-soluble liver antigen/liver-pancreas antigen antibody- positive (type 3). Recently, however, the number of atypical cases lacking the usual features has increased--for example, patients with acute-onset or fulminant-type AIH, autoantibody-negative patients, male patients, and patients with bile duct injury--and thus the clinical features of AIH have been diversified. AIH is responsive to immunosuppressive treatment in most cases; however, relapse occurs in more than 80% of patients within 1 year after immunosuppressive treatment withdrawal. The 10-year survival rate and the 10-year hepatocellular carcinoma-free rate are > 90%, respectively, indicating that some patients reach liver failure or develop hepatocellular carcinoma. To improve the prognosis of these patients, persistent normalization of transaminase is required.     

High Levels of Autoantibodies against Drug-metabolizing Enzymes in SLA/LP-positive AIH-1 Sera

Autoimmune hepatitis type 1 (AIH-1) is characterized by the detection of smooth muscle autoantibodies, antinuclear antibodies and antineutrophil cytoplasmic autoantibodies, and AIH-2 is characterized by the presence of autoantibodies against LKM, which contain drug-metabolizing enzymes. In this study, we measured the levels of drug-metabolizing enzymes in AIH-1 patients (ANA-positive). We exhaustively investigated the level of autoantibodies against major CYPs and UDP-glucuronosyltransferases of typical phase II drug-metabolizing enzymes, a transporter (MDR1), and NADPH-cytochrome P450 reductase in 4 patients with AIH-1 and 6 controls, as a case report. Two (Patients 3 and 4) of the AIH patients exhibited high levels of autoantibodies, while two (Patients 1 and 2) of the patients and the controls did not. The levels of autoantibodies against CYP2C19, CYP2D6, CYP2E1, UGT1A6 and human liver microsomes in Patients 3 and 4 sera were over 2³ times the levels in Patient 1, Patient 2 and the control sera. Meanwhile, the levels of autoantibodies against CYP1A2, CYP2A6, CYP2C9, UGT2B7, MDR1 and NADPH-cytochrome P450 reductase were 2–2² higher in Patients 3 and 4 than in the other subjects. We found that the pattern of elevation in the Patient 3 serum was not parallel with that in Patient 4. Thus, we found high levels of autoantibodies against drug-metabolizing enzymes in AIH-1 patients.     

High levels of autoantibodies against drug-metabolizing enzymes in SLA/LP-positive AIH-1 sera

Autoimmune hepatitis type 1 (AIH-1) is characterized by the detection of smooth muscle autoantibodies, antinuclear antibodies and antineutrophil cytoplasmic autoantibodies, and AIH-2 is characterized by the presence of autoantibodies against LKM, which contain drug-metabolizing enzymes. In this study, we measured the levels of drug-metabolizing enzymes in AIH-1 patients (ANA-positive). We exhaustively investigated the level of autoantibodies against major CYPs and UDP-glucuronosyltransferases of typical phase II drug-metabolizing enzymes, a transporter (MDR1), and NADPH-cytochrome P450 reductase in 4 patients with AIH-1 and 6 controls, as a case report. Two (Patients 3 and 4) of the AIH patients exhibited high levels of autoantibodies, while two (Patients 1 and 2) of the patients and the controls did not. The levels of autoantibodies against CYP2C19, CYP2D6, CYP2E1, UGT1A6 and human liver microsomes in Patients 3 and 4 sera were over 2(3) times the levels in Patient 1, Patient 2 and the control sera. Meanwhile, the levels of autoantibodies against CYP1A2, CYP2A6, CYP2C9, UGT2B7, MDR1 and NADPH-cytochrome P450 reductase were 2-2(2) higher in Patients 3 and 4 than in the other subjects. We found that the pattern of elevation in the Patient 3 serum was not parallel with that in Patient 4. Thus, we found high levels of autoantibodies against drug-metabolizing enzymes in AIH-1 patients.     

自身免疫性肝病患者自身抗体检测及临床意义

目的 探讨自身免疫性肝病患者血清中出现的自身抗体等免疫学指标及临床意义.方法 对3 500例肝功能反复异常的患者采用间接免疫荧光法检测抗核抗体(ANA)、抗平滑肌抗体(SMA)、抗线粒体抗体(AMA).并对AMAM2型及抗可溶性肝抗原/肝胰抗原(抗SLA/LP)、抗肝肾微粒体抗体Ⅰ型(抗LKM-1)和抗肝特异性胞浆抗原Ⅰ型抗体(抗LC-1)等肝脏疾病相关的自身抗体进行检测.结果 3 500例患者中,自身免疫性肝炎患者29例,检出率为0.83%,其中符合Ⅰ型、Ⅱ型、Ⅲ型自身免疫性肝炎的比例占72.4%、10.3%和17.2%.原发性胆汁性肝硬化(PBC)患者58例,检出率为1.65%,血清中AMAM2型抗体阳性率为93.1%,其中19例AMAM2阳性患者进行肝穿病理检查时12例(63.7%)患者病理提示符合PBC诊断.结论 每种自身免疫性肝病都具有特征性自身抗体谱,注重自身抗体检测对明确诊断及鉴别诊断自身免疫性肝病具有重要的临床意义.     

Autoimmune hepatitis associated with bile duct injury resembling chronic non-suppurative destructive cholangitis

Autoimmune hepatitis (AIH) and primary biliary cirrhosis (PBC) are representative autoimmune liver diseases in which hepatocytes and intrahepatic bile ducts, respectively, are selectively damaged by autoimmune mechanisms. Bile duct injury and loss is characteristic of PBC and chronic non-suppurative destructive cholangitis (CNSDC), in particular, is a histological hallmark of PBC. In this report, we present an unusual case of AIH accompanied by CNSDC-like bile duct injury in a 46-year-old woman. The patient's serum aminotransferase level was abnormally high. The serum levels of alkaline phosphatase, gamma-GTP and IgG were also elevated, but the IgM level was within normal limits. The titer of antismooth muscle antibody (SMA) was 1:80, while antinuclear autoantibody (ANA) and the M2 fraction of antimitochondrial antibody (AMA) were both negative. Liver biopsy disclosed CNSDC-like bile duct injuries and severe interface hepatitis and lobular hepatitis with perivenular zonal necrosis were observed. The aggregate score of the International Autoimmune Hepatitis Group corresponded to the category of probable AIH. Immunohistochemically, histocompatibility leukocyte antigen-DR, which is aberrantly expressed in the damaged bile ducts of PBC, was not found in the injured bile ducts of this case. Laboratory data were much improved by treatment with prednisone, but ursodeoxycholic acid was not effective. Although the possibility of an overlapping syndrome of AIH- and AMA-negative PBC could not be excluded, this case was diagnosed as AIH with CNSDC-like bile duct lesions.     

Cutting edge issues in autoimmune hepatitis

Autoimmune hepatitis (AIH) is a severe liver disease affecting all age groups worldwide. Novel basic and clinical aspects of AIH, addressed at a Monothematic Conference in London in September 2015, are highlighted in this review. The diagnosis of AIH relies upon detection of characteristic autoantibodies, hypergammaglobulinemia, and interface hepatitis on liver histology. The International Autoimmune Hepatitis Group (IAIHG) has devised diagnostic scoring systems to help in comparative studies and clinical practice. AIH arises in a genetically predisposed host, when yet unknown triggers – such an encounter with a pathogen – lead to a T cell-mediated immune response targeting liver autoantigens. This immune response is inadequately controlled because regulatory mechanisms are impaired. The mainstay of treatment for AIH is immunosuppression, which should be instituted as soon as the diagnosis is made. Standard treatment regimens include relatively high doses of predniso(lo)ne, which are tapered gradually as azathioprine is introduced. Recent guidelines have described newer treatment regimens and have tightened the goal of therapy to complete normalization of biochemical, serological and histological parameters. Mycophenolate mofetil, calcineurin inhibitors, mTOR inhibitors and biological agents are potential salvage therapies, but should be reserved for selected non-responsive patients and administered only in experienced centers. Liver transplantation is a life-saving option for those patients who progress to end-stage liver disease. Further dissection of cellular and molecular pathways involved in AIH pathogenesis is likely to lead to the discovery of novel, tailored and better tolerated therapies.     

Autoantibody detection in type 2 autoimmune hepatitis using a chimera recombinant protein

Autoantibodies against cytochrome P450 2D6 (CYP2D6), known as anti-liver/kidney microsome type 1 (LKM1) and/or anti-human formiminotransferase cyclodeaminase, formally known as anti-liver cytosol type 1 (LC1) define type 2 autoimmune hepatitis (AIH). The aims of this work are to develop a sensitive and specific test to detect anti-LKM1 and/or anti-LC1 autoantibodies and to establish the prevalence of anti-LC1. Sera from children with type 2 AIH (n=48) and those from a control group (n=100) were evaluated for anti-LKM1 and anti-LC1 by Enzyme-Linked Immunosorbent Assay (ELISA) and Western blotting. Each serum sample was assayed for reactivity against formiminotransferase cyclodeaminase and CYP2D6 alone or as part of a recombinant chimera protein. By ELISA with recombinant chimera protein, 50 serum samples were positive, 48 from patients with type 2 AIH and 2 from patients with chronic hepatitis C. Twenty-five of 48 (52%) patients studied were positive for both CYP2D6 and LC1 autoantibodies. Anti-LC1, either as the only marker or associated with anti-LKM1, was positive in 34/48 (71%). By Western blotting, anti-LC1 was found in 27/48 (56%) patients. This ELISA technique has proven to be antigen-specific and more sensitive than Western blot for the detection of anti-LC1 and anti-LKM1 autoantibodies. The prevalence of anti-LC1 (71%) confirms it as an important immunomarker in type 2 AIH.     

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.     

Autoantibodies associated with primary biliary cholangitis are common among patients with systemic lupus erythematosus even in the absence of elevated liver enzymes

Knowledge of concomitant autoimmune liver diseases (AILD) is more detailed in primary Sjögren’s syndrome (pSS) compared to systemic lupus erythematosus (SLE). Herein, the prevalence of autoantibodies associated with autoimmune hepatitis (AIH) and primary biliary cholangitis (PBC) was investigated in stored sera from patients with SLE (n = 280) and pSS (n = 114). Antibodies against mitochondria (AMA), liver–kidney microsomal (LKM) antigen, smooth muscle (SMA) and anti‐nuclear antibodies (ANA) were analysed with immunofluorescence microscopy. In addition, AILD‐associated autoantibodies were tested with immunoblot. Prior to sampling, eight SLE (2·9%) and three pSS (2·6%) cases were diagnosed with AILD. Among SLE‐cases without known AILD (n = 272), 26 (9·6%) had PBC‐associated autoantibodies, 15 (5·5%) AIH‐associated autoantibodies (excluding ANA) and one serological overlap. Most subjects with PBC‐associated autoantibodies had liver enzymes within reference limits (22 of 27, 81%) or mild laboratory cholestasis (two of 27, 7·4%), while one fulfilled the diagnostic PBC‐criteria. AMA‐M2 detected by immunoblot was the most common PBC‐associated autoantibody in SLE (20 of 272, 7·4%). The prevalence of SMA (4·4%) was comparable with a healthy reference population, but associated with elevated liver enzymes in four of 12 (25%), none meeting AIH‐criteria. The patient with combined AIH/PBC‐serology had liver enzymes within reference limits. Among pSS cases without known AILD (n = 111), nine (8·1%) had PBC‐associated, 12 (10·8%) AIH‐associated autoantibodies and two overlapped. PBC‐associated autoantibodies were found as frequently in SLE as in pSS but were, with few exceptions, not associated with laboratory signs of liver disease. Overall, AILD‐associated autoantibodies were predominantly detected by immunoblot and no significant difference in liver enzymes was found between AILD autoantibody‐negative and ‐positive patients.     

Anti-soluble liver antigen/liver-pancreas (SLA/LP) antibodies in pediatric patients with autoimmune hepatitis

Antibodies against soluble liver antigen/liver-pancreas (SLA/LP) have been associated with severe autoimmune hepatitis (AIH) and poor outcome, but most of these reports have focused on adult patients. The aim of this study was to assess the prevalence and clinical significance of anti-SLA/LP antibodies in a pediatric population with AIH. We developed a quantitative enzyme-linked immunoassay (ELISA), a Western blot (WB) and an immunoprecipitation assay (IPA) based on recombinant cDNA from activated Jurkat cells. The specificity of these tests was validated by testing 200 serum samples from healthy subjects, and from patients with liver and non-liver diseases. Anti-SLA/LP antibodies were found in patients with type 1 and type 2 AIH. The prevalence of these antibodies in patients with type 1 AIH was: 42% when tested by ELISA, 15% by WB and 50% by IPA. In patients with type 2 AIH, the prevalence rates were 42% by ELISA, 18% by WB and 44% by IPA. The mean titer values for anti-SLA/LP antibodies was significantly higher in type 2 AIH (1:1,300 +/- 339) than in type 1 AIH (1:600 +/- 71; p < 0.0001) and closely associated with higher titers of anti-liver kidney microsome type 1 (LKM1) and anti-liver cytosol type 1 (LC1) antibodies in sera. The presence of anti-SLA/LP showed a significant female preponderance in type 1 and 2 AIH patients (p = 0.0003 and p = 0.003, respectively), and was significantly correlated with a lower age at diagnosis (p = 0.05) in type 1 AIH patients. In conclusion, anti-SLA/LP antibodies in pediatric patients are associated with both type 1 and 2 AIH.