Detection of polyreactive immunoglobulin G facilitates diagnosis in children with autoimmune hepatitis.

OBJECTIVE: The detection of autoantibodies is essential to diagnose autoimmune hepatitis (AIH). Particularly in children, specificity of autoantibodies decreases due to lower titers being diagnostic and being present not only in AIH but also in other liver diseases. Recently, quantification of polyreactive IgG (pIgG) for detection of adult AIH showed the highest overall accuracy compared to antinuclear antibodies (ANA), anti-smooth muscle antibodies (anti-SMA), anti-liver kidney microsomal antibodies (anti-LKM) and anti-soluble liver antigen/liver pancreas antibodies (anti-SLA/LP). We aimed to evaluate the diagnostic value of pIgG for pediatric AIH. DESIGN: pIgG, quantified using HIP1R/BSA coated ELISA, and immunofluorescence on rodent tissue sections were performed centrally. The diagnostic fidelity to diagnose AIH was compared to conventional autoantibodies of AIH in training and validation cohorts from a retrospective, European multi-center cohort from nine centers from eight European countries composed of existing biorepositories from expert centers (n = 285). RESULTS: IgG from pediatric AIH patients exhibited increased polyreactivity to multiple protein and non-protein substrates compared to non-AIH liver diseases and healthy children. pIgG had an AUC of 0.900 to distinguish AIH from non-AIH liver diseases. pIgG had a 31-73% higher specificity than ANA and anti-SMA and comparable sensitivity that was 6-20 times higher than of anti-SLA/LP, anti-LC1 and anti-LKM. pIgG had a 21-34% higher accuracy than conventional autoantibodies, was positive in 43-75% of children with AIH and normal IgG and independent from treatment response. CONCLUSION: Detecting pIgG improves the diagnostic evaluation of pediatric AIH compared to conventional autoantibodies, primarily owing to higher accuracy and specificity.

The evolving phenotype of autoimmune hepatitis across the millennium: The 40-year experience of a referral centre in Italy.

BACKGROUND AND AIMS: During recent years, there have been major insight into the pathogenesis, diagnosis and treatment of autoimmune hepatitis (AIH). We aim to evaluate modifications of the clinical-epidemiological phenotype of AIH patients from 1980 to our days. METHODS: Single-centre, tertiary care retrospective study on 507 consecutive Italian patients with AIH. Patients were divided into four subgroups according to the decade of diagnosis: 1981-1990, 1991-2000, 2001-2010 and 2011-2020. We assessed clinical, laboratory and histological features at diagnosis, response to treatment and clinical outcomes. Acute presentation is defined as transaminase levels >10-fold the upper limit and/or bilirubin >5 mg/dL. Complete response is defined as the normalization of transaminases and IgG after 12 months. Clinical progression is defined as the development of cirrhosis in non-cirrhotic patients and hepatic decompensation/hepatocellular carcinoma development in compensated cirrhosis. RESULTS: Median age at diagnosis increased across decades (24, 31, 39, 52 years, p < .001). Acute onset became more common (39.6%, 44.4%, 47.7%, 59.5%, p = .019), while cirrhosis at diagnosis became less frequent (36.5%, 16.3%, 10.8%, 8.7%, p < .001). Complete response rates rose (11.1%, 49.4%, 72.7% 76.2%, p < .001) and clinical progression during follow-up decreased (54.3%, 29.9%, 16.9%, 11.2%, p < .001). Anti-nuclear antibodies positivity increased (40.7%, 52.0%, 73.7%, 79.3%, p < .001), while IgG levels/upper limit progressively decreased (1.546, 1.515, 1.252, 1.120, p < .001). Liver-related death and liver transplantation reduced from 17.1% to 2.1% (p < .001). CONCLUSIONS: In the new millennium, the typical AIH patient in Italy is older at diagnosis, more often presents with acute hepatitis, cirrhosis is less frequent and response to treatment is more favourable.

Paraneoplastic Anti-Tif1-gamma Autoantibody-positive Dermatomyositis as Clinical Presentation of Hepatocellular Carcinoma Recurrence.

Hepatocellular carcinoma (HCC) is rarely associated with autoimmune paraneoplastic syndromes. We report a case of anti-transcriptional intermediary factor-1 gamma (TIF1-γ)-positive dermatomyositis (DM) as clinical presentation of HCC recurrence in a 72-year-old male patient admitted to our hospital due to fatigue, myalgia, and typical skin rash. His medical history was notable for hepatitis C-related cirrhosis, successful treatment with direct-acting antiviral agents, and previously efficacious treatment of HCC. Laboratory testing showed significant rhabdomyolysis with anti-TIF1-γ antibodies at high titer, and DM was diagnosed. After a careful diagnostic workup, HCC recurrence was diagnosed. After first-line corticosteroid treatment, azathioprine and intravenous immunoglobulin treatments were administered; unfortunately, he mounted only partial response. Owing to the compromised performance status, no HCC treatment was feasible, and, according to international guidelines, he received only best supportive care. Here, we discuss the diagnostic, prognostic, and pathogenic roles of anti-TIF1-γ antibodies associated with paraneoplastic DM and the scant literature data on its occurrence in HCC patients. Considering the TIF1 gene family's established role in oncogenesis, we also review the role of TIF1-γ as a tumor-related neoantigen, leading to the development of clinically overt anti-TIF1-γ antibodies-positive DM.

Quantification of polyreactive immunoglobulin G facilitates the diagnosis of autoimmune hepatitis.

BACKGROUND AND AIMS: Detection of autoantibodies is a mainstay of diagnosing autoimmune hepatitis (AIH). However, conventional autoantibodies for the workup of AIH lack either sensitivity or specificity, leading to substantial diagnostic uncertainty. We aimed to identify more accurate serological markers of AIH with a protein macroarray. APPROACH AND RESULTS: During the search for more-precise autoantibodies to distinguish AIH from non-AIH liver diseases (non-AIH-LD), IgG antibodies with binding capacities to many human and foreign proteins were identified with a protein macroarray and confirmed with solid-phase ELISAs in AIH patients. Subsequently, polyreactive IgG (pIgG) was exemplarily quantified by reactivity against human huntingtin-interacting protein 1-related protein in bovine serum albumin blocked ELISA (HIP1R/BSA). The diagnostic fidelity of HIP1R/BSA binding pIgG to diagnose AIH was assessed in a retrospective training, a retrospective multicenter validation, and a prospective validation cohort in cryoconserved samples from 1,568 adults from 10 centers from eight countries. Reactivity against HIP1R/BSA had a 25% and 14% higher specificity to diagnose AIH than conventional antinuclear and antismooth muscle antibodies, a significantly higher sensitivity than liver kidney microsomal antibodies and antisoluble liver antigen/liver pancreas antigen, and a 12%-20% higher accuracy than conventional autoantibodies. Importantly, HIP1R/BSA reactivity was present in up to 88% of patients with seronegative AIH and in up to 71% of AIH patients with normal IgG levels. Under therapy, pIgG returns to background levels of non-AIH-LD. CONCLUSIONS: pIgG could be used as a promising marker to improve the diagnostic workup of liver diseases with a higher specificity for AIH compared to conventional autoantibodies and a utility in autoantibody-negative AIH. Likewise, pIgG could be a major source of assay interference in untreated AIH.

Hepatocellular carcinoma in viral and autoimmune liver diseases: Role of CD4+ CD25+ Foxp3+ regulatory T cells in the immune microenvironment.

More than 90% of cases of hepatocellular carcinoma (HCC) occurs in patients with cirrhosis, of which hepatitis B virus and hepatitis C virus are the leading causes, while the tumor less frequently arises in autoimmune liver diseases. Advances in understanding tumor immunity have led to a major shift in the treatment of HCC, with the emergence of immunotherapy where therapeutic agents are used to target immune cells rather than cancer cells. Regulatory T cells (Tregs) are the most abundant suppressive cells in the tumor microenvironment and their presence has been correlated with tumor progression, invasiveness, as well as metastasis. Tregs are characterized by the expression of the transcription factor Foxp3 and various mechanisms ranging from cell-to-cell contact to secretion of inhibitory molecules have been implicated in their function. Notably, Tregs amply express checkpoint molecules such as cytotoxic T lymphocyte-associated antigen 4 and programmed cell-death 1 receptor and therefore represent a direct target of immune checkpoint inhibitor (ICI) immunotherapy. Taking into consideration the critical role of Tregs in maintenance of immune homeostasis as well as avoidance of autoimmunity, it is plausible that targeting of Tregs by ICI immunotherapy results in the development of immune-related adverse events (irAEs). Since the use of ICI becomes common in oncology, with an increasing number of new ICI currently under clinical trials for cancer treatment, the occurrence of irAEs is expected to dramatically rise. Herein, we review the current literature focusing on the role of Tregs in HCC evolution taking into account their opposite etiological function in viral and autoimmune chronic liver disease, and we discuss their involvement in irAEs due to the new immunotherapies.

COVID-19 and Immunological Dysregulation: Can Autoantibodies be Useful?

Coronavirus disease 2019 (COVID-19) is often associated with interstitial pneumonia. However, there is insufficient knowledge on the presence of autoimmune serological markers in patients with COVID-19. We analyzed the presence and role of autoantibodies in patients with COVID-19-associated pneumonia. We prospectively studied 33 consecutive patients with COVID-19, 31 (94%) of whom had interstitial pneumonia, and 25 age-matched and sex-matched patients with fever and/or pneumonia with etiologies other than COVID-19 as the pathological control group. All patients were tested for the presence of antinuclear antibodies (ANAs), anti-antiphospholipid antibodies, and anti-cytoplasmic neutrophil antibodies (ANCAs). Clinical, biochemical, and radiological parameters were also collected. Fifteen of 33 patients (45%) tested positive for at least one autoantibody, including 11 who tested positive for ANAs (33%), 8 who tested positive for anti-cardiolipin antibodies (immunoglobulin (Ig)G and/or IgM; 24%), and 3 who tested positive for anti-ß2-glycoprotein antibodies (IgG and/or IgM; 9%). ANCA reactivity was not detected in any patient. Patients that tested positive for auto-antibodies had a significantly more severe prognosis than other patients did: 6 of 15 patients (40%) with auto-antibodies died due to COVID-19 complications during hospitalization, whereas only 1 of 18 patients (5.5%) who did not have auto-antibodies died (P = 0.03). Patients with poor prognosis (death due to COVID-19 complications) had a significantly higher respiratory rate at admission (23 breaths per minute vs. 17 breaths per minute; P = 0.03) and a higher frequency of auto-antibodies (86% vs. 27%; P = 0.008). In conclusion, auto-antibodies are frequently detected in patients with COVID-19 possibly reflecting a pathogenetic role of immune dysregulation. However, given the small number of patients, the association of auto-antibodies with an unfavorable prognosis requires further multicenter studies.

Clinical and prognostic implications of acute onset of Autoimmune Hepatitis: An Italian multicentre study.

Autoimmune Hepatitis (AIH) can present under clinical profile as acute hepatitis of unexplained cause. We analyzed clinical, therapeutical and prognostic implications of AIH presenting as acute hepatitis in a cohort of patients admitted to 3 referral Centres in Italy. AIH onset was considered acute when transaminases were higher than 10 times the normal limit and/or bilirubin higher than 5 mg/ml (irrespectively from the histology, available only in 62% of cases). Among 479 patients diagnosed as AIH, 202 (43%) met the criteria of acute onset. This former group of patients on the basis of the histology has been subdivided in the "genuine" acute onset (83 pts) and acute "on chronic" onset (45 pts) At onset, clinical acute AIH showed significantly higher ALT, bilirubin and INR levels (p < 0.001 for all), lower albumin values (p = 0.001), similar IgG levels; Response to treatment was similar between the two groups. The progression to liver cirrhosis or its complications was significantly less frequent in acute onset AIH (13% vs. 22%, p = 0.02). The "genuine" acute patients showed a higher albumin serum levels (40 vs. 36, p = 0.001), lower INR levels (1.12 vs. 1.26, p = 0.002) and less tendency to the progression of liver disease (7% vs. 12%, p = NS) with respect to acute "on chronic" onset patients. Clinical acute hepatitis represents a common presentation of AIH, responds to standard immunosuppression regimen and would seem to be correlated with a better long-term prognosis.

Hyperferritinemia and hypergammaglobulinemia predict the treatment response to standard therapy in autoimmune hepatitis.

Autoimmune hepatitis (AIH) is a chronic hepatitis with an increasing incidence. The majority of patients require life-long immunosuppression and incomplete treatment response is associated with a disease progression. An abnormal iron homeostasis or hyperferritinemia is associated with worse outcome in other chronic liver diseases and after liver transplantation. We assessed the capacity of baseline parameters including the iron status to predict the treatment response upon standard therapy in 109 patients with untreated AIH type 1 (AIH-1) in a retrospective single center study. Thereby, a hyperferritinemia (> 2.09 times upper limit of normal; Odds ratio (OR) = 8.82; 95% confidence interval (CI): 2.25-34.52) and lower immunoglobulins (<1.89 times upper limit of normal; OR = 6.78; CI: 1.87-24.59) at baseline were independently associated with the achievement of complete biochemical remission upon standard therapy. The predictive value increased when both variables were combined to a single treatment response score, when the cohort was randomly split into a training (area under the curve (AUC) = 0.749; CI 0.635-0.863) and internal validation cohort (AUC = 0.741; CI 0.558-0.924). Patients with a low treatment response score (<1) had significantly higher cumulative remission rates in the training (p<0.001) and the validation cohort (p = 0.024). The baseline hyperferritinemia was accompanied by a high serum iron, elevated transferrin saturations and mild hepatic iron depositions in the majority of patients. However, the abnormal iron status was quickly reversible under therapy. Mechanistically, the iron parameters were not stringently related to a hepatocellular damage. Ferritin rather seems deregulated from the master regulator hepcidin, which was down regulated, potentially mediated by the elevated hepatocyte growth factor. In conclusion, baseline levels of serum ferritin and immunoglobulins, which are part of the diagnostic work-up of AIH, can be used to predict the treatment response upon standard therapy in AIH-1, although confirmation from larger multicenter studies is pending.

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.

Clinical implications of antimitochondrial antibody seropositivity in autoimmune hepatitis: a multicentre study.

BACKGROUND/AIM: Antimitochondrial antibody (AMA) positivity is the serological marker of primary biliary cholangitis (PBC), but can also be sporadically detected in autoimmune hepatitis (AIH). Little is known about the clinical significance of AMA in AIH. PATIENTS AND METHODS: We recruited 47 AMA-positive AIH cases from several centres and compared them with 264 well-characterized Italian AIH patients. Cases with any features of PBC were excluded. RESULTS: In univariate analysis, AMA-positive AIH patients were older (46 vs. 36, P=0.002) and more responsive to immunosuppression (74 vs. 59%, P=0.05), but no differences were observed between the two groups after logistic regression using AMA as a dependent variable. None of the AMA-positive AIH patients showed signs of evolving PBC features after a median follow-up of up 47 months. AMA was detected in combination with all serological AIH markers except antiliver kidney microsome type 1 and antiliver cytosol type 1. AMA was the only marker of autoimmunity in eight cases. CONCLUSION: We found no differences between AIH with and without AMA. The groups had similar clinical, biochemical and histological features. AMA-positive AIH patients did not evolve towards PBC. In some cases, AMA was the only autoantibody.

Predictive factors of poor response to therapy in Autoimmune Hepatitis.

AIM: To evaluate "ex ante" the predictive factors of incomplete/absent response to the standard therapy in a well characterized series of Autoimmune Hepatitis (AIH) patients from Italy. METHODS: Of 282 AIH patients screened from our database 166 (59%) had a sustained response and 116 (41%) had an incomplete/absent response to the therapy; all patients were analyzed for the clinical, serological and histological parameters at diagnosis. RESULTS: The patients with incomplete/absent response were characterized by significantly younger age (30 aa vs 42 aa p=0.001) and a significantly higher frequency of cirrhosis at diagnosis than patients who had a complete response to therapy (26% vs 3% p<0.0001); furthermore, patients with incomplete/absent response were distinguished from those with a complete response for significantly lower serum levels of both AST (7.9×upper normal limit [unl] vs 13×unl p<0.005) and ALT (10.9×unl vs 18×unl p=0.002) at diagnosis, and by an increase in IgG serum levels (1.43×unl vs 1.27×unl p=0.009). After stepwise logistic regression, cirrhosis at diagnosis (p=0.003, OR 0.12, 95% CI 0.03-0.49) and younger age (p=0.001, OR 1.03, 95% CI 1.01-1.05) represent two independent variables of incomplete/absent response. CONCLUSIONS: Younger age and cirrhosis are predictive of lack of response to the standard therapy in AIH patients.

Features and Progression of Asymptomatic Autoimmune Hepatitis in Italy.

BACKGROUND & AIMS: Patients with autoimmune hepatitis (AIH) can present with symptoms ranging from those that are insidious and nonspecific to acute hepatitis with jaundice. However, some patients have no symptoms at diagnosis and are identified incidentally. We investigated disease progression and outcomes of these 2 groups of patients. METHODS: We performed a retrospective study to compare clinical, immunologic, and histologic features and outcomes of patients with asymptomatic vs. symptomatic AIH. We analyzed data collected from 305 patients (90 asymptomatic and 215 with symptoms), diagnosed with AIH from 1994 and 2013, at the Center for the Study and Treatment of the Autoimmune Diseases of the Liver and Biliary System in Bologna, Italy. RESULTS: At diagnosis, patients with asymptomatic AIH had significantly lower mean levels of alanine aminotransferase (7.0- ± 8.0-fold the upper limit of normal) than patients with symptomatic disease (23.0- ± 18.0-fold the upper limit of normal; P < .001), and lower mean levels of bilirubin (1.4 ± 1.4 mg/dL vs. 8.6 ± 10.4 mg/dL; P < .001). Asymptomatic patients also had significantly lower histologic grades (7.0 ± 2.5) than symptomatic patients (9.0 ± 2.9; P < .001). However, larger proportions of asymptomatic patients had anti-liver/kidney microsomal antibodies type 1 (26.8% vs. 13.1%; P < .006), and associated autoimmune thyroid (26.7% vs. 12.6%; P = .003) or skin (8.9% vs. 2.3%; P = .010) disorders. Age at onset, sex, response to therapy, disease progression, genetic factors, and other autoantibody markers did not differ between patients with asymptomatic vs. symptomatic disease. CONCLUSIONS: Patients with asymptomatic vs. symptomatic AIH have similar courses of disease progression and responses to immunosuppressive agents, and therefore should receive the same treatment. Patients affected by thyroid or dermatologic autoimmune disorders are at increased risk of developing subclinical liver disease, and should be assessed routinely for AIH.

Autoantibodies in Autoimmune Hepatitis.

BACKGROUND: The detection of diagnostic autoantibodies such as antinuclear antibodies (ANA), anti-smooth muscle antibodies (SMA), anti-liver/kidney microsomal type 1 (anti-LKM1), anti-liver cytosol type 1 (anti-LC1) and anti-soluble liver antigen (anti-SLA) is historically associated with the diagnosis of autoimmune hepatitis. KEY MESSAGES: When autoimmune hepatitis is suspected, the detection of one or any combination of diagnostic autoantibodies, by indirect immunofluorescence or immuno-enzymatic techniques with recombinant antigens, is a pivotal step to reach a diagnostic score of probable or definite autoimmune hepatitis. CONCLUSIONS: Diagnostic autoantibodies (ANA, SMA, anti-LKM1, anti-LC1, anti-SLA) are a cornerstone in the diagnosis of autoimmune hepatitis. Other ancillary autoantibodies, associated with peculiar clinical correlations, appear to be assay-dependent and institution-specific, and validation studies are needed.

Autoimmune liver disease and concomitant extrahepatic autoimmune disease.

AIM: To assess the frequency and clinical impact of associated extrahepatic autoimmune diseases (EAD) on autoimmune liver diseases (ALD). PATIENTS AND METHODS: We investigated 608 patients with ALD (327 autoimmune hepatitis - AIH and 281 primary biliary cirrhosis - PBC) for concomitant EAD. RESULTS: In both AIH and PBC, we observed a high prevalence of EAD (29.9 and 42.3%, respectively); both diseases showed a significant association with autoimmune thyroid disease, followed by autoimmune skin disease, celiac disease, and vasculitis in AIH patients and sicca syndrome, CREST syndrome, and celiac disease in PBC patients. At diagnosis, AIH patients with concurrent EAD were more often asymptomatic than patients with isolated AIH (P<0.01). CONCLUSION: Our study confirms the strict association between ALD and EAD, in particular with autoimmune thyroid disease. In the light of our results, all patients with an EAD should be assessed for the concomitant presence of an asymptomatic ALD.

Fatigue and pruritus at onset identify a more aggressive subset of primary biliary cirrhosis.

BACKGROUND & AIMS: In recent years, primary biliary cirrhosis is mostly diagnosed in patients who are asymptomatic; however, a proportion of cases still present with typical complaints such as fatigue and/or pruritus. We compared biochemical, histological and immunological features of patients with or without fatigue and/or pruritus at onset to see whether the different clinical presentation may eventually impact on disease progression. METHODS: We analysed the Bologna cohort of 216 patients with primary biliary cirrhosis referred to our Centre between 1997 and 2007, according to symptomatic (fatigue and/or pruritus) or asymptomatic presentation. Clinical, biochemical, histological and immunological feature at diagnosis, response to ursodeoxycholic acid and progression of the disorder were compared after a mean follow-up of 81 ± 75 months. RESULTS: At diagnosis, symptomatic patients were significantly more often women (98.6% vs. 87.2%, P = 0.004), younger (mean age 49 ± 12 vs. 55 ± 12 years, P = 0.003) and with more pronounced biochemical activity, as indicated by higher alkaline phosphatase (mean 2.93 ± 2 vs. 2.12, P = 0.002) and aminotransferase (mean 1.92 ± 1 vs. 1.47 ± 1.27, P = 0.014) levels, whereas histological stage and autoantibody profile were similar. Symptomatic patients were less likely to respond to ursodeoxycholic acid therapy (63% vs. 81%, P = 0.006) and developed more often cirrhosis and its complications (31% vs. 13%, P = 0.004). CONCLUSIONS: Fatigue and/or pruritus at onset identify a subset of patients with primary biliary cirrhosis who preferentially are women, younger, with a particularly active disease, less responsive to ursodeoxycholic acid treatment, and more inclined to evolve to cirrhosis and its complications.

Redistribution of regulatory T-cells across the evolving stages of chronic hepatitis C.

BACKGROUND: Hepatitis C virus infection frequently leads to chronic hepatitis, possibly evolving to end-stage liver disease and hepatocellular carcinoma. Regulatory T cells can affect antiviral immune response thus influencing the outcome of the disease. AIM: To determine numeric and functional distribution of regulatory T cells expressing CD4+CD25hiFoxp3+ (T-regs) during the different stages of hepatitis C virus-related liver disease. METHODS: 90 hepatitis C viraemic patients and 50 healthy controls were included. Surface and intracellular (Foxp3) T-reg markers were evaluated by flow cytometry. Target cell proliferation and interferon-gamma production were evaluated in 37 HCV patients. In 16 cases intrahepatic distribution of Foxp3 by immuno-histochemistry was assessed. RESULTS: T-regs were increased in hepatitis C virus infected patients and correlated inversely with aminotransferases and directly with MELD score and disease duration. A preserved inhibitory ability of interferon-gamma production was distinctive of patients with normal aminotransferases. Circulating T-regs did not correlate with intrahepatic distribution of Foxp3. CONCLUSIONS: In chronic hepatitis C, selective expansion of peripheral T-regs in patients with normal aminotransferases and advanced disease suggests that, though a continual low level inflammation does not prevent liver disease progression, once cirrhosis has developed it may represent an attempt to prevent immuno-mediated decompensation.

A multifaceted imbalance of T cells with regulatory function characterizes type 1 autoimmune hepatitis.

UNLABELLED: Immunotolerance is maintained by regulatory T cells (Tregs), including CD4(+)CD25(hi), CD8(+)CD28(-), gammadelta, and CD3(+)CD56(+) [natural killer T (NKT)] cells. CD4(+)CD25(hi) cells are impaired in children with autoimmune hepatitis (AIH). Little is known about Tregs in adults with AIH. The aim of this study was to investigate the frequency and function of Treg subsets in adult patients with AIH during periods of active disease and remission. Forty-seven AIH patients (16 with active disease and 31 in remission) and 28 healthy controls were studied. Flow cytometry was used to evaluate surface markers and function-related intracellular molecules in gammadelta, CD8(+)CD28(-), NKT, and CD4(+)CD25(hi) cells. CD4(+)CD25(hi) T cell function was determined by the ability to suppress proliferation and interferon gamma (IFN-gamma) production by CD4(+)CD25(-) target cells. Liver forkhead box P3-positive (FOXP3(+)) cells were sought by immunohistochemistry. In AIH patients, particularly during active disease, CD4(+)CD25(hi) T cells were fewer, expressed lower levels of FOXP3, and were less effective at inhibiting target cell proliferation versus healthy controls. Moreover, although the numbers of CD8(+)CD28(-) T cells were similar in AIH patients and healthy controls, NKT cells were numerically reduced, especially during active disease, and produced lower quantities of the immunoregulatory cytokine interleukin-4 versus controls. In contrast, gammadelta T cells in AIH patients were more numerous versus healthy controls and had an inverted Vdelta1/Vdelta2 ratio and higher IFN-gamma and granzyme B production; the latter was correlated to biochemical indices of liver damage. There were few FOXP3(+) cells within the portal tract inflammatory infiltrate. CONCLUSION: Our data show that the defect in immunoregulation in adult AIH is complex, and gammadelta T cells are likely to be effectors of liver damage.