T-lymphocyte subsets in liver tissues of patients with primary biliary cirrhosis (PBC), patients with primary sclerosing cholangitis (PSC), and normal controls

Beyond FOXP3: a 20-year journey unravelling human regulatory T-cell heterogeneity

The initial idea of a distinct group of T-cells responsible for suppressing immune responses was first postulated half a century ago. However, it is only in the last three decades that we have identified what we now term regulatory T-cells (Tregs), and subsequently elucidated and crystallized our understanding of them. Human Tregs have emerged as essential to immune tolerance and the prevention of autoimmune diseases and are typically contemporaneously characterized by their CD3+CD4+CD25high CD127lowFOXP3+ phenotype. It is important to note that FOXP3+ Tregs exhibit substantial diversity in their origin, phenotypic characteristics, and function. Identifying reliable markers is crucial to the accurate identification, quantification, and assessment of Tregs in health and disease, as well as the enrichment and expansion of viable cells for adoptive cell therapy. In our comprehensive review, we address the contributions of various markers identified in the last two decades since the master transcriptional factor FOXP3 was identified in establishing and enriching purity, lineage stability, tissue homing and suppressive proficiency in CD4+ Tregs. Additionally, our review delves into recent breakthroughs in innovative Treg-based therapies, underscoring the significance of distinct markers in their therapeutic utilization. Understanding Treg subsets holds the key to effectively harnessing human Tregs for immunotherapeutic approaches.

ANXA1 is identified as a key gene associated with high risk and T cell infiltration in primary sclerosing cholangitis

BACKGROUND

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease, with unclear pathogenesis. Although immune disorders, especially T cell infiltration, are thought to play a vital role in PSC, the specific pathogenesis mechanisms remain incompletely understood. This study evaluated the potential key gene associated with the PSC pathogenesis and analyzed the associations of the key gene with prognosis and immune cell infiltration by combining bioinformatics analysis and experimental verification.

METHODS

Transcriptome data of PSC and normal human liver tissues (GSE159676) were obtained from the gene expression omnibus database. Differentially expressed genes (DEGs) were identified, and differences in biological states were analyzed. A protein-protein interaction (PPI) network was constructed. Hub genes were identified, and their expression was verified using transcriptome data of mice fed 0.1% 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) and Mdr2-/- mice (GSE179993, GSE80776), as well as by immunohistochemistry staining on clinical samples. The correlations between the key gene and other factors were evaluated by Pearson's correlation coefficient. Immune cell infiltration into human liver (GSE159676) was analyzed by xCell and verified by immunofluorescence staining on PSC liver samples.

RESULTS

Of the 185 DEGs identified, 113 were upregulated and 72 were downregulated genes in PSC. Genes associated with immune cell infiltration and fibrosis were significantly enriched in PSC. PPI network showed close interactions among DEGs. A module strongly associated with immune infiltration was identified, with annexin A1 (ANXA1) being the core gene. High expression of ANXA1 in PSC was confirmed in two public datasets and by immunohistochemistry staining on clinical samples. High ANXA1 expression was strongly associated with high-risk score for PSC. Also, ANXA1 expression was positively associated with chemokines and chemokine receptors and with the infiltration of immune cells, especially T cells, into liver with PSC. Immune infiltration, fibrosis, and cancer-related processes were markedly enriched in PSC with high expression of ANXA1.

CONCLUSION

ANXA1 is a key gene associated with high risk and infiltration of immune cells, especially T cells, in PSC. These findings provide new insight into the key biomarker of PSC and suggest that targeting ANXA1 may be a valuable strategy for the treatment of PSC.

Challenges and opportunities in achieving effective regulatory T cell therapy in autoimmune liver disease

Autoimmune liver diseases (AILD) include autoimmune hepatitis (AIH), primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC). These immune-mediated liver diseases involve a break down in peripheral self-tolerance with largely unknown aetiology. Regulatory T cells (Treg) are crucial in maintaining immunological tolerance. Hence, Treg immunotherapy is an attractive therapeutic option in AILD. Currently, AILD do not have a curative treatment option and patients take life-long immunosuppression or bile acids to control hepatic or biliary inflammation. Clinical investigations using good manufacturing practice (GMP) Treg in autoimmune liver disease have thus far demonstrated that Treg therapy is safe and that Treg migrate to inflamed liver tissue. For Treg immunotherapy to achieve efficacy in AILD, Treg must be retained within the liver and maintain their suppressive phenotype to dampen ongoing immune responses to hepatocytes and biliary epithelium. Therefore, therapeutic Treg subsets should be selected for tissue residency markers and maximal functionality. Optimisation of dosing regime and understanding longevity of Treg in vivo are critical to successful Treg therapy. It is also essential to consider combination therapy options to complement infused Treg, for instance low-dose interleukin-2 (IL-2) to support pre-existing and infused Treg survival and suppressive function. Understanding the hepatic microenvironment in both early- and late-stage AILD presents significant opportunity to better tailor Treg therapy in different patient groups. Modification of a hostile microenvironment to a more favourable one either prior to or during Treg therapy could enhance the efficacy and longevity of infused GMP-Treg. Applying recent technology to discovery of autoantigen responses in AILD, T cell receptor (TCR) sequencing and use of chimeric antigen receptor (CAR) technology represents the next frontier for disease-specific CAR-Treg therapies. Consideration of all these aspects in future trials and discovery research would position GMP Treg immunotherapy as a viable personalised-medicine treatment option for effective control of autoimmune liver diseases.

Inclusion body myositis: clinical features and pathogenesis

Inclusion body myositis (IBM) is often viewed as an enigmatic disease with uncertain pathogenic mechanisms and confusion around diagnosis, classification and prospects for treatment. Its clinical features (finger flexor and quadriceps weakness) and pathological features (invasion of myofibres by cytotoxic T cells) are unique among muscle diseases. Although IBM T cell autoimmunity has long been recognized, enormous attention has been focused for decades on several biomarkers of myofibre protein aggregates, which are present in <1% of myofibres in patients with IBM. This focus has given rise, together with the relative treatment refractoriness of IBM, to a competing view that IBM is not an autoimmune disease. Findings from the past decade that implicate autoimmunity in IBM include the identification of a circulating autoantibody (anti-cN1A); the absence of any statistically significant genetic risk factor other than the common autoimmune disease 8.1 MHC haplotype in whole-genome sequencing studies; the presence of a marked cytotoxic T cell signature in gene expression studies; and the identification in muscle and blood of large populations of clonal highly differentiated cytotoxic CD8⁺ T cells that are resistant to many immunotherapies. Mounting evidence that IBM is an autoimmune T cell-mediated disease provides hope that future therapies directed towards depleting these cells could be effective.

In situ characterization of intrahepatic non-parenchymal cells in PSC reveals phenotypic patterns associated with disease severity

Liver-infiltrating T cells have been implicated in the pathogenesis of primary sclerosing cholangitis (PSC), however little information is available about changes in other cellular compartments in the liver during PSC. This study aimed to characterize non-parenchymal intrahepatic cells in PSC livers and to find associations between phenotypes and disease severity. Using immunohistochemistry, followed by automated image analysis and quantification and a principal component analysis, we have studied non-parenchymal intrahepatic cells in PSC-patient livers (n = 17) and controls (n = 17). We observed a significant increase of T cells in the PSC patients, localized to the fibrotic areas. MAIT cells, normally present at high numbers in the liver, were not increased to the same extent. PSC patients had lower expression of MHC class I than controls. However, the levels of NKp46+ NK cells were similar between patients and controls, nevertheless, NKp46 was identified as a phenotypic marker that distinguished PSC patients with mild from those with severe fibrosis. Beyond that, a group of PSC patients had lost expression of Caldesmon and this was associated with more extensive bile duct proliferation and higher numbers of T cells. Our data reveals phenotypic patterns in PSC patients associated with disease severity.

Increased T-helper 2 cytokines in bile from patients with IgG4-related cholangitis disrupt the tight junction-associated biliary epithelial cell barrier

BACKGROUND & AIMS

IgG4-related cholangitis is a chronic inflammatory biliary disease that involves different parts of the pancreatobiliary system, but little is known about its mechanisms of pathogenesis. A T-helper (Th) 2 cell cytokine profile predominates in liver tissues from these patients. We investigated whether Th2 cytokines disrupt the barrier function of biliary epithelial cells (BECs) in patients with IgG4-related cholangitis.

METHODS

We assessed the Th2 cytokine profile in bile samples and brush cytology samples from 16 patients with IgG4-related cholangitis and respective controls, and evaluated transcription of tight junction (TJ)-associated proteins in primary BECs from these patients. The effect of Th2 cytokines on TJ-mediated BEC barrier function and wound closure was examined by immunoblot, transepithelial resistance, charge-selective Na(+)/Cl(-) permeability, and 4-kDa dextran flux analyses.

RESULTS

Bile samples from patients with IgG4-related cholangitis had significant increases in levels of Th2 cytokines, interleukin (IL)-4, and IL-5. IL-13 was not detected in bile samples, but polymerase chain reaction analysis of whole-brush cytology samples from patients with IgG4-related cholangitis revealed increased levels of IL-13 mRNA, compared with controls. BECs isolated from the brush cytology samples revealed decreased levels of claudin-1 and increased levels of claudin-2 mRNAs. In vitro, IL-4 and IL-13 significantly reduced TJ-associated BEC barrier function by activating claudin-2-mediated paracellular pore pathways. Th2 cytokines also impaired wound closure in BEC monolayers.

CONCLUSIONS

Th2 cytokines predominate in bile samples from patients with IgG4-related cholangitis and disrupt the TJ-mediated BEC barrier in vitro. Subsequent increases in biliary leaks might contribute to the pathogenesis of chronic biliary inflammation in these patients.

The immunobiology of primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease histologically characterized by the presence of intrahepatic and/or extrahepatic biliary duct concentric, obliterative fibrosis, eventually leading to cirrhosis. Approximately 75% of patients with PSC have inflammatory bowel disease. The male predominance of PSC, the lack of a defined, pathogenic autoantigen, and the potential role of the innate immune system suggest that it may be due to dysregulation of immunity rather than a classic autoimmune disease. However, PSC is associated with several classic autoimmune diseases, and the strongest genetic link to PSC identified to date is with the human leukocyte antigen DRB01*03 haplotype. The precise immunopathogenesis of PSC is largely unknown but likely involves activation of the innate immune system by bacterial components delivered to the liver via the portal vein. Induction of adhesion molecules and chemokines leads to the recruitment of intestinal lymphocytes. Bile duct injury results from the sustained inflammation and production of inflammatory cytokines. Biliary strictures may cause further damage as a result of bile stasis and recurrent secondary bacterial cholangitis. Currently, there is no effective therapy for PSC and developing a rational therapeutic strategy demands a better understanding of the disease.

Characterization of CD4, CD8, CD56 positive lymphocytes and C4d deposits to distinguish acute cellular rejection from recurrent hepatitis C in post-liver transplant biopsies

INTRODUCTION

Hepatitis C viral (HCV) infection is the most common cause for liver transplantation (LTx) in USA. Hepatitis C viral recurrence in liver allograft is almost universal, which is often difficult to distinguish from acute cellular rejection (ACR).

AIM

Aim of the present study is to examine the differences between distribution of CD4, CD8, CD56 positive lymphocytes, and C4d deposits in patients with ACR and recurrent HCV.

PATIENTS AND METHODS

As a pilot project, a group of five post-LTx HCV RNA negative patients, strongly suspicious for ACR based on clinical findings and history of medication non-compliance and another group of five post-LTx HCV positive, medication compliant patients with abnormal liver function were retrospectively selected. Liver biopsies of these patients were stained with monoclonal CD4, CD8, CD56, and polyclonal C4d antibodies and compared.

RESULTS

Mean CD4, CD8, and CD56 counts in ACR group were 156.7 +/- 17.6, 35.4 +/- 8.8, and 1.0 +/- 1.8/HPF, respectively and were 89.7 +/- 41.3, 20.3 +/- 23.2, and 0.6 +/- 0.9/HPF, respectively in HCV recurrence group. Biopsies of four of five patients with ACR demonstrated moderate to strong C4d staining, whereas all patients with recurrent HCV had none to mild C4d staining.

CONCLUSION

Mean CD4, CD8, and CD56 were similar for acute rejection and recurrent HCV infection. However, 80% of patients with ACR showed moderate to strong staining for C4d and all recurrent HCV patients showed none to mild C4d staining.

B7-2 positive cells around interlobular bile ducts in primary biliary cirrhosis and chronic hepatitis C

Bile duct damage in patients with chronic hepatitis C (hepatitis-associated bile duct lesion) as well as that in patients with primary biliary cirrhosis (PBC; chronic non-suppurative destructive cholangitis), may be causally related to immunological assaults. Efficient antigen presentation is known to require the provision of a costimulatory signal which is dependent on the CD28 on T cell surfaces, and that at least two molecules, B7-1 and B7-2, work as costimulatory ligands for CD28. In this study, we examined immunohistochemically, the expression of B7-2 in portal tracts of liver biopsy specimens obtained from 75 patients with chronic hepatitis C who had hepatitis-associated bile duct lesions, and from 63 PBC patients with chronic non-suppurative destructive cholangitis. B7-2 positive cells were recognizable as large mononuclear cells scattered in portal tracts. Some of these cells showed a dendritic cell-like appearance. B7-2 positive cells were observed more frequently (41%) in PBC liver specimens than in chronic hepatitis C specimens (17%, P < 0.05). In PBC livers, such cells were preferentially observed around the damaged bile duct with a few located in the biliary epithelial layer. There was no such finding in chronic hepatitis C livers. The frequency and density of B7-2 positive cells in the liver specimens tended to decrease according to the stage of PBC (45% in stages 1 and 2, and 33% in stages 3 and 4; P = 0.10), whereas with chronic hepatitis C, no such tendency was observed. These findings suggest that B7-2 positive cells may play a role in the bile duct lesions that appear in the early histological stages of PBC and that the immunological mechanisms of bile duct damage, particularly of antigen presentation and B7-2 expression, differ between PBC and chronic hepatitis C.

Differential expression of the major histocompatibility antigens and ICAM-1 on bile duct epithelial cells in biliary atresia

Aberrant expression on biliary epithelial cells of the major histocompatibility complex (MHC) antigens in association with adhesion molecule intercellular adhesion molecule-1 (ICAM-1) may be crucial to the immunopathogenesis of biliary atresia. The patterns of MHC class I and II expression in relation to ICAM-1 expression as well as the associated lymphocyte subpopulations were studied in frozen section liver biopsies from six infants with biliary atresia. Intense ICAM-1 expression was found on all ductal epithelial cells in association with MHC I. No ductal epithelial cells demonstrated MHC II expression. Lymphocyte populations within the portal tracts all expressed LFA-1 and were predominantly CD4 positive (> 70%). CD8 positive cells accounted for less than 30%. The expression of ICAM-1 appears to be important in the pathogenesis of biliary atresia but is not linked to the expression of MHC II determinants. This result suggests that different regulatory mechanisms govern the expression of these important immunological receptors on biliary epithelial cells.

Heterogeneity of autoreactive T cell clones specific for the E2 component of the pyruvate dehydrogenase complex in primary biliary cirrhosis

The extraordinary specificity of bile duct destruction in primary biliary cirrhosis (PBC) and the presence of T cell infiltrates in the portal tracts have suggested that biliary epithelial cells are the targets of an autoimmune response. The immunodominant antimitochondrial response in patients with PBC is directed against the E2 component of pyruvate dehydrogenase (PDC-E2). Hitherto, there have only been limited reports on the characterization and V beta usage of PDC-E2-specific cloned T cell lines. In this study, we examined peripheral blood mononuclear cells (PBMC) for their reactivity to the entire PDC complex as well as to the E1- and E2-specific components. We also examined the phenotype, lymphokine profile, and V beta usage of PDC-specific T cell clones isolated from cellular infiltrates from the livers of PBC patients. We report that PBMC from 16/19 patients with PBC, but not 12 control patients, respond to the PDC-E2 subunit. Interestingly, this response was directed to the inner and/or the outer lipoyl domains, despite the serologic observation that the autoantibody response is directed predominantly to the inner lipoyl domain. Additionally, lymphokine analysis of interleukin (IL) 2/IL-4/interferon gamma production from individual liver-derived autoantigen-specific T cell clones suggests that both T helper cell Th1- and Th2-like clones are present in the liver. Moreover, there was considerable heterogeneity in the T cell receptor for antigen (TCR) V beta usage of these antigen-specific autoreactive T cell clones. This is in contrast to murine studies in which animals are induced to develop autoimmunity by specific immunization and have an extremely limited T cell V beta repertoire. Thus, our data suggest that in human organ-specific autoimmune diseases, such as PBC, the TCR V beta repertoire is heterogenous.

Primary biliary cirrhosis presenting with granulomatous skin lesions

A case is described of primary biliary cirrhosis in a 59 year old woman who initially presented with a rash over her lower legs 18 months before diagnosis. Skin biopsy examination showed non-caseating granulomas of the sarcoid type. It is believed that this is the first reported case of primary biliary cirrhosis presenting with a granulomatous rash.

Is there recurrence of primary biliary cirrhosis after liver transplantation? A clinicopathologic study in long-term survivors

Liver transplantation has been accepted as a successful therapeutic tool for irreversible liver diseases such as primary biliary cirrhosis. However, removal of the diseased liver may not eliminate this autoimmune disease, and recurrence of primary biliary cirrhosis in the liver graft has been reported as early as within the first posttransplant year. We studied whether or not primary biliary cirrhosis recurs after liver transplantation in follow-up biopsies of 19 primary biliary cirrhosis patients. Biopsies of 14 non-primary biliary cirrhosis patients served as controls. The median follow-up period was 5 years (range 1-11 years). Both groups of patients were selected according to strict criteria which excluded pre- and posttransplant diseases which could mimic primary biliary cirrhosis. The follow-up biopsies were taken according to a protocol at yearly intervals. Established histologic criteria for primary biliary cirrhosis were assessed semi-quantitatively in 119 biopsies in a coded fashion. A longitudinal study was performed after decoding the biopsies, to document the course of morphological changes in time per patient. In addition to data on liver tests and immunosuppression, anti-mitochondrial antibodies including the primary biliary cirrhosis specific subtypes (anti-PDH-E2 and BCKD-E2) were determined in freeze-stored serum samples. The biopsies showed a striking concordance between the primary biliary cirrhosis and non-primary biliary cirrhosis groups and few overt histologic abnormalities. There was no significant difference in liver-test results and immunosuppression. Overall anti-mitochondrial antibodies remained present in decreased titers.(ABSTRACT TRUNCATED AT 250 WORDS)

Is primary biliary cirrhosis an autoimmune disease?

This review summarizes the experimental and clinical support for an autoimmune origin of primary biliary cirrhosis (PBC). Direct proof is lacking, but indications in favour of an immunologic destructive mechanism include the demonstration of antibodies and T cell clones with specificity for mitochondrial autoantigens, and the lymphocytic infiltration/destruction of small bile ducts similar to that of graft-vs-host disease and rejection. There is a weak association with other autoimmune diseases, but no clear HLA linkage. Spontaneous animal models for PBC are lacking, and immunization of animals with purified autoantigen does not result in typical disease. Anti-mitochondrial antibodies (AMAs) of M2 type are diagnostic of PBC, and are mainly directed against a functional, restricted epitope on the E2 subunit of the pyruvate dehydrogenase complex (PDC). PDC-E2 shows several similarities to other classical autoantigens. The pathogenic role of AMA remains elusive. Recent studies have shown that AMAs detect an antigenic epitope expressed on the luminal surface of biliary epithelium in PBC liver. The initial triggering event might represent a microbial infection (molecular mimicry), or an aberrant surface expression of a true autoepitope.

Autoantibodies in sclerosing cholangitis against a shared peptide in biliary and colon epithelium

BACKGROUND/AIMS

A strong association exists between ulcerative colitis and primary sclerosing cholangitis (PSC). Previously, the presence of a unique epitope shared by colon and biliary epithelial cells was shown by using the novel monoclonal antibody (MAb) 7E12H12 developed against a colonic epithelial protein. In the present study, the presence of circulating autoantibody in PSC against this peptide was examined.

METHODS

Sera from 16 patients with PSC, 13 with primary biliary cirrhosis, 6 with secondary biliary stricture, and 6 with chronic liver diseases and 10 normal subjects were used. An inhibition immunoperoxidase assay using the 7E12H12 MAb was developed against sections of bile duct and gallbladder. Sera were also examined in an enzyme-linked immunosorbent assay (ELISA) against the gallbladder extract enriched in 7E12H12-reactive protein.

RESULTS

About two thirds of the sera from patients with PSC blocked the binding of 7E12H12 MAb on the bile duct and gallbladder, whereas non-PSC sera did not. In the ELISA, 93% of PSC sera had circulating immunoglobulin G antibodies against the enriched gallbladder extract. The reactivity of sera from the PSC group was significantly (P < 0.01 to P < 0.0001) higher than in each of the non-PSC groups.

CONCLUSIONS

Sera from patients with PSC contains autoantibodies against a cross-reactive peptide shared by colon and biliary epithelial cells.

Immunohistochemical characterization of hepatic lymphocytes in primary biliary cirrhosis in comparison with primary sclerosing cholangitis and autoimmune chronic active hepatitis

We analyzed the immunophenotypes of hepatic cellular infiltrates by quantitative immunohistochemical methods in biopsy specimens from 20 patients with primary biliary cirrhosis (PBC), 19 with primary sclerosing cholangitis, and 11 with autoimmune chronic active hepatitis. Specifically, we sought to identify activated T cells, interferon-gamma-producing cells, and natural killer cells. The portal cellular infiltrate in PBC contained a preponderance of CD4 cells in comparison with CD8 cells, with a CD4/CD8 ratio of 2.45:1. The cellular infiltrate in areas of piecemeal necrosis contained mostly CD8 cells. Infiltrating CD8 cells in PBC had the surface phenotype of cytotoxic (CD8-positive, CD11b-negative) cells. Approximately 4% of T cells expressed interleukin 2 receptors. Interferon-gamma-staining cells were rarely identified (in less than 2%). Cells that expressed the natural killer cell markers CD16, CD56, or CD57 were infrequent, constituting approximately 5% of the cellular infiltrate. The composition of the infiltrates was similar in patients with PBC and chronic active hepatitis. Natural killer cells were twice as common in patients with primary sclerosing cholangitis (P < 0.05) as in those with PBC. The inflammatory infiltrates in areas of piecemeal necrosis were similar in the three diseases and differed from those found within the portal area, in that CD8 cells were preponderant. In all three liver diseases, almost 90% of bile ducts expressed class II HLA antigens. These findings support the hypothesis that cytotoxic T cells of either the CD4 or CD8 immunophenotype but not natural killer cells may be involved in the pathogenesis of PBC and chronic active hepatitis.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunohistochemical features of the portal tract mononuclear cell infiltrate in chronic aggressive hepatitis

The portal tract mononuclear cell infiltrate has been characterised in 28 liver biopsy samples showing features of chronic aggressive hepatitis from 12 patients with autoimmune chronic active hepatitis, 12 with primary sclerosing cholangitis, and four with other chronic liver diseases (two with alpha 1-antitrypsin deficiency, one with Wilson's disease, and one with chronic hepatitis B infection). In all patients liver disease had started in childhood. The mononuclear cell infiltrate was investigated by a two step immunoperoxidase technique using monoclonal antibodies to: total, alpha/beta T cell receptor positive, helper/inducer, suppressor/cytotoxic T lymphocytes; B lymphocytes; killer/natural killer cells; monocyte/macrophages; and to the activation markers HLA-DR antigens, interleukin 2 receptor (IL-2R), transferrin receptor, and 4F2Ag. In all samples the infiltrate consisted of mainly alpha/beta T cell receptor T lymphocytes. Although T helper/inducer cells predominated in patients with autoimmune chronic active hepatitis, T suppressor/cytotoxic lymphocytes were preponderant in patients with primary sclerosing cholangitis and the other chronic liver diseases. Killer/natural killer cells accounted for up to 25% of the mononuclear cell infiltrate in patients with autoimmune chronic active hepatitis, being rare or absent in the other diseases. Monocytes/macrophages were always found, but they were more numerous in primary sclerosing cholangitis than in the other chronic liver diseases. B lymphocytes were rare or absent in all subjects. Activated mononuclear cells were present in all subjects, but although in patients with autoimmune chronic active hepatitis and primary sclerosing cholangitis most cells of the infiltrate expressed HLA-DR antigens and up to 75% IL-2R, in other forms of chronic liver diseases HLA-DR positive cells were less common and IL-2R positive cells ere rare or absent. These results show that the cells responsible for the histological characteristics of chronic aggressive hepatitis vary in their functional phenotype and state of activation according to the type of underlying liver disorder, confirming the involvement of different pathogenetic mechanisms.

Ulcerative colitis disease activity as subjectively assessed by patient-completed questionnaires following orthotopic liver transplantation for sclerosing cholangitis

To assess whether or not liver transplantation and subsequent immunosuppression with cyclosporine and prednisone affect ulcerative colitis symptomatology, we surveyed by questionnaire all 23 surviving patients with pretransplant colonoscopy-documented ulcerative colitis who were transplanted for primary sclerosing cholangitis between June 1982 and September 1985. At follow-up [89.8 +/- 7.6 weeks (mean +/- SEM], all six patients who had had asymptomatic colonoscopy-documented ulcerative colitis reported continued ulcerative colitis quiescence. Among the 17 patients who had had symptomatic colonoscopy-documented ulcerative colitis at time of liver transplantation, 88.2% reported improvement in overall ulcerative colitis severity (P less than 0.001), with significant improvement in the frequency of bowel movements reported by 100%, in crampy abdominal pain by 87.5%, in bowel urgency by 75%, in the occurrence of pus or mucus in stool by 87.5%, in the incidence of ulcerative colitis flares by 81.8%, and in the number of days unable to function normally due to ulcerative colitis symptoms by 78.6% (all at least P less than 0.01). These data demonstrate that ulcerative colitis symptom severity significantly improves following liver transplantation with immunosuppression with cyclosporine and prednisone.

Genes for interleukin-1, interleukin-6, and tumor necrosis factor are expressed at markedly reduced levels in the livers of patients with severe liver disease

The genes for interferon (IFN) alpha, IFN gamma, IL-1 beta, IL-6, and TNF alpha were transcribed at readily detectable levels both in liver biopsies from individuals with normal liver function and in samples of normal viable liver taken for transplantation. These results provided evidence for the concept that such multifunctional cytokines play a role in homeostasis in normal human tissues. In normal human liver, in situ hybridization studies showed that, in the absence of a detectable inflammatory response, both hepatocytes and mononuclear cells exhibited a similar degree of expression of IL-6 mRNA in keeping with the finding that IL-6 is produced by cells of different lineages. The levels of IL-1, IL-6, and TNF mRNA were found to be markedly reduced in extracts of the livers of patients with primary biliary cirrhosis and other forms of autoimmune liver disease at a time when extensive liver lesions were apparent, compared to the levels of expression of these cytokines in the livers of normal individuals. The reduced expression of IL-1, IL-6, and TNF mRNAs appeared to be a specific effect and not due to a general reduction in RNA synthesis as the IFN alpha, IFN gamma and actin mRNAs were expressed at similar levels in both normal and diseased livers. The levels of IL-1 beta, IL-6, and TNF mRNAs were also reduced in samples of liver from a patient with a drug induced fulminant hepatitis suggesting that this specific pattern of altered cytokine gene expression was characteristic of the advanced stage of severe liver disease.

Lymphocytes from hepatic inflammatory infiltrate kill rat hepatocytes in primary culture. Comparison with peripheral blood lymphocytes

In the last few years it has become possible in the liver to isolate lymphocytes from inflammatory infiltrates and to culture them in vitro. Most of the lymphocyte clones obtained are CD 8+ cytotoxic cells, but interactions between these lymphocytes and hepatocytes in primary culture have not been analysed previously. In this study, cloned human T lymphocytes from liver biopsies and from the peripheral blood of patients with chronic hepatitis B or primary biliary cirrhosis, after phenotypical and functional characterization into CD 8+ or CD 4+ cytotoxic lymphocytes, were activated in an antigen-independent fashion by adding either anti CD 3 or anti CD 2/R-3 monoclonal antibodies to the cell suspension. The activated cells were then coincubated with rat hepatocytes in primary culture. The killing capacity of the activated lymphocytes was monitored by light and electron microscopy and by measurement of lactic dehydrogenase (LDH)-release into the culture medium. It was found that cytotoxic CD 8+, but not CD 4+ helper lymphocytes very effectively killed hepatocytes. The killing effect was dependent on the time of cocultivation and on effector-target (E/T) ratio. Total breakdown of the hepatocyte monolayer was achieved after 10-20 h coculture and at an E/T ratio of 10 to 1. As LDH-release in the culture medium reached about 80% of the total LDH-content, most of the hepatocytes were lysed by activated lymphocytes. Cytotoxic activity of clones obtained from different biopsies was comparable with that of clones from peripheral blood. Hepatocytes in primary culture seem to be very sensitive to the killing capacity of activated cytotoxic lymphocytes.

The effect of recombinant interferon-alpha on lymphocyte subpopulations and HLA-DR expression on liver tissue of HBV-positive individuals

Interferon-alpha (IFN-alpha) has been reported to be beneficial in the treatment of chronic active hepatitis occurring as a result of hepatitis B virus (HBV) infection. Treatment with IFN-alpha has been proposed as a means of reducing the high rate of allograft infection in clinical liver transplantation in patients transplanted for HBV-related chronic active hepatitis and cirrhosis who are positive for hepatitis B surface antigen (HBsAg). We obtained resected whole livers from two groups of patients who received liver transplants. Group A consisted of 11 patients who were HBsAg+ but were not treated with IFN-alpha, and group B consisted of 10 patients who were also HBsAg+ but received IFN-alpha therapy for 29.4 +/- 5.6 days prior to orthotopic liver transplantation. No differences between the two groups existed in terms of a variety of demographic and clinical characteristics. The liver tissue was stained with monoclonal antibodies to cell surface antigens unique to different mononuclear cell populations by the avidin-biotin-immunoperoxidase technique to determine the effect of IFN-alpha on the lymphocyte subsets as well as HLA antigen expression on liver-infiltrating mononuclear cells. The number of HLA-DR+ lymphocytes in the liver was significantly increased (P less than 0.005) within the portal areas in group B compared with that found in group A (84 +/- 14 versus 33 +/- 5 per one high-power field). Moreover, the intensity of the HLA-DR antigen expression on lymphocytes in the portal areas (P less than 0.02) and in the hepatic lobule (P less than 0.05) was greater in group B than in group A. The number of natural killer (NK) cells was increased in the portal areas (P less than 0.05) of group B compared with group A. These alterations in the lymphocyte and NK cell populations present in the liver in response to IFN-alpha therapy presumably reflect an IFN-alpha-induced enhancement of the immune response to virus-infected cells.

Isolation, phenotyping, and functional analysis of lymphocytes from human liver

The isolation of mononuclear cells from human liver tissues was achieved by a simple method consisting of enzymatic and mechanical dissociation, density gradient centrifugation, and adherence to plastic. The method was optimized to obtain a nearly complete recovery of different lymphoid subpopulations. The mononuclear cells recovered from "normal" liver tissues consisted of 33 +/- 9% (mean +/- SD) small lymphocytes, 44 +/- 6% large granular lymphocytes, 9 +/- 2% monocytes/macrophages, 9 +/- 3% granulocytes, and 5 +/- 2% other cells as determined by microscopic analysis of May-Grünwald-Giemsa-stained cytocentrifuge smears. Phenotypic analysis of the liver-infiltrating lymphocytes (LIL) by two-color flow cytometry showed that CD3-CD56+ NK cells represented 43 +/- 6% (mean +/- SD), CD3+CD56- T cells, 30 +/- 9%, and CD19+ B cells 3 +/- 1%. The predominant phenotype of the liver-infiltrating NK cells was CD3-CD56+CD16- in contrast to that of circulating NK cells, which are largely CD3-CD56+CD16+. The alpha/beta TCR+ T cells were 42 +/- 14% and gamma/delta T cells were infrequent (4 +/- 4%). The proportions of the three major lymphoid populations (T, NK, and B cells) recovered from liver tissues of 10 patients with different liver diseases were altered. Tissue sections from the same specimens were stained by the immunoperoxidase method to compare the in situ cellular composition with that determined by flow cytometry. LIL recovered from normal (control) and virally infected (non-A, non-B hepatitis) liver tissues had high NK activity (up to 1,000 LU/10(7) cells) as measured against K-562 targets in 4-hr 51Cr-release assays. NK activity was significantly lower (P less than 0.05) in LIL recovered from other liver diseases. LIL had spontaneous cytotoxicity against NK-resistant Daudi targets which was significantly higher (P less than 0.05) in control and virally infected than in other liver tissues. Our results indicated that human LIL recovered from normal and diseased liver tissues contained a high proportion of functionally active NK cells and that NK and lymphokine-activated killer activities but not the percentages of CD56+ cells were decreased in end-stage primary biliary cirrhosis and primary sclerosing cholangitis. In contrast, the proportions of NK cells and NK activity remain high in non-A, non-B hepatitis.

Aetiology and pathophysiology of chronic liver disorders

The aetiology of chronic liver disease covers a wide range of congenital or acquired abnormalities of the hepatocellular biochemical network. Although our knowledge has considerably increased in recent years, the aetiology of chronic liver disease often remains obscure. Acquired irreversible disturbances of normal liver function can be mediated by hepatotrophic viruses, chemicals, chronic oxygen depletion, or interference with the immune system. Considerable progress has been made in the detection and characterisation of hepatitis B, C, and D viruses as causative agents of chronic active hepatitis. Alcohol abuse remains the predominant cause of chronic liver disease in the Western world. The targets of autoantibodies used to diagnose autoimmune diseases of the liver and primary biliary cirrhosis continue to be biochemically defined. Their significance for the aetiology of the disease, however, remains to be established. Nonparenchymal cells play an important role in the sequence of events following hepatocellular injury and ultimately leading to liver cirrhosis. They release vasoactive compounds, cytokines, and other important mediators, and participate in the modulation of the extracellular matrix that is characteristic of liver fibrosis and cirrhosis. The biochemical basis of liver cell necrosis remains poorly defined. In spite of recent progress, and the detection of some new pathogenic principles that help in the understanding of the complications of chronic liver disease such as portal hypertension, oesophagogastric variceal bleeding, portosystemic encephalopathy, ascites, and other metabolic disturbances, many questions concerning the aetiology and pathophysiology of chronic liver disease and its complications remain to be answered.

Alpha-interferon. Its effect upon lymphocyte subpopulations and HLA-DR expression within the liver

Alpha-interferon (IFN-alpha) has been shown to be beneficial in the treatment of chronic active hepatitis occurring as a consequence of hepatitis B virus (HBV) infection. Therefore, it has been used to reduce the high rate of allograft infection in clinical liver transplantation of HBV-positive individuals. This study was performed to evaluate the effect of IFN-alpha on lymphocyte subsets as well as the HLA-DR antigen expression in liver tissue. The resected livers obtained from two groups of patients who received liver transplants between 1983 and 1987 at the University of Pittsburgh were examined: group A consisted of 11 patients who were not treated (controls), and group B consisted of 10 patients (experimental group) who were treated with IFN-alpha for 29.4 +/- 5.6 days prior to transplantation. No differences between the two groups existed in terms of a variety of demographic and clinical characteristics. Both groups had cirrhosis as a result of chronic HBV infection. Monoclonal antibodies to cell-surface antigens unique to different lymphocyte populations and the HLA-DR antigens were used in conjunction with the avidin-biotin-immunoperoxidase technique to identify cells in tissue sections. The number of HLA-DR-positive lymphocytes in the liver was increased (P less than 0.005) within the portal areas in rIFN-alpha-treated group as compared to that seen in the untreated group (84.4 +/- 13.6/HPF vs 33.3 +/- 4.8/HPF). Moreover, the intensity of the HLA-DR antigen expression in the portal areas (P less than 0.02) and in the hepatic lobule (P less than 0.05) was greater in the treated group than in untreated group.(ABSTRACT TRUNCATED AT 250 WORDS)

Phenotypic characterization of mononuclear infiltrate present in liver of biliary atresia

The liver tissue of 26 children with biliary atresia was compared to that of 20 adults with autoimmune chronic active hepatitis, 20 adults with chronic hepatitis due to hepatitis B infection, and 5 children with alpha 1-antitrypsin deficiency in terms of the number and type of mononuclear cells in portal and lobular areas of each using a panel of specific monoclonal antibodies that recognize different cell surface epitopes. All of the tissues studied were obtained at time of liver transplantation. In addition the livers of 5 adults biopsied for hepatomegaly but found to have no histologic liver disease were used as normal controls for this study. The results demonstrate that liver tissue obtained from children with end-stage biliary atresia is more like normal liver in terms of the number and type of mononuclear cells present than in either of the two types of adult liver diseases. Moreover although the liver of children with end-stage alpha 1-antitrypsin deficiency is more like that of normal liver than either of the two adult liver diseases studied in terms of the number and type of mononuclear cells within the liver, it is less similar to that of normal adult liver than is liver tissue obtained from children with biliary atresia. These findings suggest that as a morphologic basis biliary atresia is unlikely to be due to either a viral or an autoimmune attack upon the liver.

Peripheral blood and portal tract lymphocyte populations in primary sclerosing cholangitis

The relative distribution of lymphocyte subpopulations in the blood and liver of patients with primary sclerosing cholangitis (PSC) and related diseases has been studied using immunoenzyme techniques. The peripheral blood CD4/CD8 T lymphocyte ratio was significantly higher in active ulcerative colitis (UC) and in PSC with inactive UC than in inactive UC alone. In contrast, no relationship with disease activity was seen in Crohn's disease. The portal tract t lymphocyte count per high power field (mean +/- S.D.) was higher in pre-cirrhotic PSC (173 +/- 105) and primary biliary cirrhosis (PBC: 210 +/- 110) than in histologically normal liver (42 +/- 27). However, the overall portal tract CD4/CD8 ratio was similar in PSC (1.49), PBC (1.89) and normal controls (1.63). The results are consistent with immunological involvement in the pathogenesis of PSC, but argue against the hypothesis that changes in the peripheral blood T cell subsets are due to sequestration at the site of tissue inflammation.

Primary biliary cirrhosis

Primary biliary cirrhosis is a chronic liver disease of unknown etiology characterized by slowly progressive intrahepatic cholestasis due to an inflammatory destruction of small intrahepatic bile ducts. The clinical course of PBC is variable ranging from a few years in rapidly progressive cases to a normal life-expectancy in a proportion of asymptomatic cases. The typical patient is a middle-aged woman who may present with pruritus, increasing pigmentation of the skin, and eventually jaundice. The level of serum alkaline phosphatase is almost invariably elevated, serum mitochondrial antibodies are present in more than 90 per cent, and an elevated serum IgM is usually present. PBC is associated with many immunologic abnormalities and appears to be a classic autoimmune disease. Some of the immune defects may be epiphenomena; others such as a marked defect in suppressor T cell function seem to be related to the pathogenesis of the disease. All drug therapy that is aimed at slowing the disease process is experimental. A place for immunosuppressive drugs in the management of PBC would be anticipated. However, no drug has to date been definitively shown to have a beneficial effect on the disease. Currently, the main treatments used are aimed at preventing or correcting the complications of intractable cholestasis. Patients with PBC and evidence of hepatic decompensation and/or poor quality of life make good candidates for liver transplantation. The current aim of therapy is to find an effective regime of immunosuppression that will make hepatic transplantation redundant for this disease.

S100 protein positive dendritic cells in primary biliary cirrhosis and other chronic inflammatory liver diseases. Relevance to pathogenesis?

A study to determine the location of dendritic cells, in chronic inflammatory liver disease was performed. S100 protein positivity and dendritic cytoplasmic morphology were used to identify dendritic cells. S100 protein positive dendritic cells (S100 + DC) were found inside the basement membrane between biliary epithelial cells of septal bile ducts of livers affected by early stage PBC, but were not present at later stages. S100 + DC also were seen in areas of piecemeal necrosis in chronic active hepatitis of various etiologies. In contrast, intra-epithelial S100 + DC were not found with any consistency in sclerosing cholangitis, secondary biliary cirrhosis, extrahepatic biliary atresia, or chronic liver allograft rejection, all of which are characterized by inflammatory bile duct damage. The possible relevance of DC in the pathogenesis of PBC is discussed.

Progression of autoimmune damage in primary biliary cirrhosis: an immunohistochemical study

Aberrant MHC Class II antigen expression and the nature of the infiltrating lymphoid cells were studied by immunohistochemical techniques in liver biopsies from 37 patients with Primary biliary cirrhosis (PBC) (11 histological stage I, 13 stage II-III, 13 stage IV) and 15 patients with chronic non autoimmune liver disease. Bile duct epithelial cells expressed HLA-DR, DP and DQ antigens in biopsies from patients with early (Stage I) PBC and less frequently in the late cirrhotic phases of the disease (Stage IV); these observations support the hypothesis that induction of Class II antigens on epithelial cells may be involved in initiating autoimmune responses towards bile duct components. The presence of cytotoxic/suppressor T cells around the bile ducts in Stage I suggests a role for cell mediated destruction of the ducts at this early stage. The nature of the chronic inflammatory cell infiltrate in the portal tracts, periportal areas and lobular parenchyma does not establish the mechanism(s) involved in disease progression. However, the lack of Class II antigen expression on hepatocytes is compatible with the hypothesis that hepatocellular damage is non-specific and may be secondary to the initial bile duct injury.

Relationship between the diagnosis, preoperative evaluation, and prognosis after orthotopic liver transplantation

The purpose of this study was to identify which of the biochemical, immunological, or functional parameters derived before surgery as part of a systemic evaluation were helpful in predicting the frequency of rejection episodes, the chance of survival, and the cause risk of death (should death occur) of patients after orthotopic liver transplantation (OLTx). Ninety-eight adult patients who had an extensive preoperative protocol evaluation were studied before OLTx. The biochemical parameters assessed were albumin, prothrombin time, bilirubin, and ICG clearance. The immunologic parameters assessed included total lymphocytes, T3 cells, T4 cells, T8 cells, and the T4/T8 ratio. The degree of histocompatibility antigen (HLA) matching between the donor and the recipient was also evaluated in 80 of the 98 patients studied. Most postoperative deaths occurred within 12 weeks of the procedure (24%; 24 of 98 patients); 13 patients (13%) died within the first 6 postoperative weeks, of either bacterial or fungal sepsis. An additional 14 patients (14%) died after the initial 6 postoperative weeks due, primarily of an acquired viral and/or protozoan infection (p less than 0.01). During the first 6 weeks, survival was better for patients with cholestatic liver disease (ChLD, 93%, n = 45) and miscellaneous liver diseases (MISC, 100%, n = 10) than it was for those with parenchymal liver diseases (PLD, 77%, n = 43). Although albumin, prothrombin time, T4/T8 ratios, and per cent T8 cells were statistically different in patients with PLD as compared with those with ChLD, these parameters, as well as the per cent T4 cells, serum bilirubin level, per cent retention of ICG at 15 minutes, and the plasma ICG disappearance rate were not found to be of substantial help in predicting patient survival or non-survival. Moreover, neither the degree of HLA matching nor the number of rejection episodes differed between surviving and nonsurviving patients. The results of this study suggest that patients with PLD are at increased risk of early postoperative death after OLTx because of bacterial and/or fungal sepsis, as compared with patients operated upon for ChLD. Better pre-, intra-, and postoperative predictors of risk of death and complications are needed to reduce the early mortality observed after orthotopic liver transplantation.

Clinical and statistical analyses of new and evolving therapies for primary biliary cirrhosis

Primary biliary cirrhosis is a chronic, progressive, cholestatic liver disease thought to be related to abnormalities in immune regulation. The disease is associated with granulomatous bile duct destruction, cholestasis, hepatic copper overloading and the development of hepatic fibrosis or cirrhosis or both. There have been numerous therapeutic trials evaluating immunosuppressive, antifibrotic and cupruretic agents. Prednisolone, D-penicillamine, azathioprine, colchicine and chlorambucil have been evaluated in controlled clinical trials, and biochemical improvement of liver function has been noted with all of the agents, except D-penicillamine. Improved survival has also been reported in patients treated long-term with azathioprine and colchicine. However, none of the therapeutic agents has been demonstrated to halt histologic progression of the disease or to induce a complete clinical, biochemical and histologic remission as has been reported in patients with autoimmune chronic active hepatitis treated with corticosteroids. Many of the trials did not use a double-blind design, failed to use the "intent to treat" rule or failed to define an objective time to analyze results. Many of the studies involved small numbers of patients with short-term follow-up and thus potentially were inadequate to appreciate drug effects that might be of clinical benefit. Currently, there is no totally effective therapy for primary biliary cirrhosis. We believe that well-designed clinical trials can provide important information to better understand this disease until a totally effective therapy is available. New clinical trials should use well-established methodologic guidelines in study design and well-accepted statistical standards in the analysis and interpretation of results.

Sarcoidosis and primary biliary cirrhosis. Coexistence in a single patient

An unusual case of a woman with primary biliary cirrhosis and cutaneous sarcoidosis is described. The factors that allow a specific diagnosis of each condition are presented and the literature pertaining to such complex and unusual cases is presented.

Immunoelectron microscopic observations on the inflammatory infiltrates and HLA antigens in hepatitis B and non-A, non-B

The present knowledge of the inflammatory reaction occurring in situ during hepatitis B favors a T cell-dependent MHC-restricted immune response. However, the reports in the literature are primarily based on the application of monoclonal antibodies directed at different lymphocyte subsets which discern only lymphocytic phenotypes and do not reflect the actual situation adequately. Therefore, we investigated the liver biopsies of patients with hepatitis B (28 patients) and non-A, non-B (21 patients) by immunoelectron microscopy with monoclonal antibodies directed at lymphocyte subtypes (pan-B, pan-T, T8, T4 and NKH1) and at activation epitopes (IL-2 receptor, TA1 and T11/3) as well, in order to determine the phenotype in association with the activation status of the lymphocytes that are in close contact with hepatocytes; thus, establishing an effector-target cell relationship on the ultrastructural level. We were able to confirm the central role of T8 lymphocytes being the predominant type of lymphocytes in close contact with liver cells in the space of Disse. A certain percentage of these cells expressed "activation" markers as IL-2 receptor, TA1 and T11/3. In acute hepatitis, the NK lymphocytes made up a fifth of all lymphocytes, whereas their number dropped below 10% in the chronic stage. There was a vague correlation between the inflammatory activity of the disease and the expression of HLA antigens (both classes I and II) on inflammatory cells and also on hepatocytes. The results did not show significant differences between hepatitis B and non-A, non-B.(ABSTRACT TRUNCATED AT 250 WORDS)

Induction of DR/IA antigens in human liver allografts. An immunocytochemical and clinicopathologic analysis of twenty failed grafts

Twenty failed human liver allograft specimens obtained at the time of retransplantation procedures were studied using a panel of monoclonal antibodies (T11, T4, T8, NK, B1, OKM1, OKM5, Ia, DR). A clinicopathologic analysis was used to distinguish between graft failures secondary to rejection (n = 10) and those due, at least in part, to other causes (n = 10). T lymphocytes constituted the major infiltrating cellular population in the liver in rejection cases, but significant numbers of B cells and monocytes/macrophages were present also. Following transplantation, but not before, the bile duct epithelium, as well as portal and central vein and hepatic artery endothelium expressed DR/Ia antigens. These structures are preferential targets of the rejection reaction. The selective destruction of bile ducts in livers undergoing rejection was manifested in these patients by striking elevations of serum gamma glutamyl transpeptidase (GGTP) activity, a marker of biliary epithelial damage. The induced expression of DR/Ia antigens on structures targeted for immune destruction may be an important event in the pathogenesis of liver allograft rejection.

Immunologic analysis of mononuclear cells in liver tissues and blood of patients with primary sclerosing cholangitis

Using monoclonal antibodies to surface antigens, we typed and quantitated the mononuclear cells (MNCs) infiltrating liver tissues from 23 patients with primary sclerosing cholangitis. The circulating T lymphocytes were also enumerated by flow cytometry in 12 of these patients. In blood, T lymphocytes and especially T8+ cells were decreased. T cells were the major components of MNCs (78%) in portal tracts. Few of these cells were Tac+ or HLA-DR+. Total MNCs (929 +/- 90 vs. 106 +/- 18 in controls) included 11% M1+ and 8% B1+ cells. Aggregates of T4+ and T8+ cells were common in portal areas. The portal T4/T8 ratio of 1.27 +/- 0.1 was significantly (p less than 0.01) different than that around proliferating bile ductules (0.8 +/- 0.1). The T8+ and M5+ cells localized in these areas of proliferation and infiltrated ductal epithelium. On the other hand, T4+ cells accumulated on the parenchymal side of fibrosed tissue and densely surrounded certain intralobular bile ducts. Even late in the disease, variability in the extent of MNCs infiltration, ductal proliferation and periductal fibrosis was seen in each biopsy.

Studies of lymphocyte subpopulations in the liver tissue and blood of patients with chronic active hepatitis (CAH)

Monoclonal antibodies to antigens on the surfaces of mononuclear cells (MNC) were used to characterize lymphocyte subpopulations infiltrating portal areas and parenchyma of livers in 31 patients with chronic active hepatitis (CAH). The distribution and numbers of infiltrating lymphocytes were determined in serial sections immunostained by the avidin-biotin-peroxidase complex method. T lymphocytes were the major component of inflammatory cells in the portal tracts. In the peripheral blood and portal areas, T helper-inducer (T4+) cells were the more numerous subpopulation. However, the hepatic lobules and areas of "piecemeal" necrosis always contained more T suppressor-cytotoxic (T8+) cells. The latter were demonstrated in contact with HBsAg-containing hepatocytes in tissues of patients with HBsAg-positive CAH. The mean numbers of T lymphocytes infiltrating the portal and periportal areas of livers from patients with HBsAg-negative and HBsAg-positive CAH were not different. Large numbers of B cells forming distinct follicles were seen in tissues from patients with HBsAg-positive CAH. The presence of increased numbers of portal T and B lymphocytes correlated with progressive liver damage as observed in two patients studied at yearly intervals.