Clonal analysis of human T lymphocytes infiltrating the liver in chronic active hepatitis B and primary biliary cirrhosis

Immunophenotypes and Cytotoxic Functions of Lymphocytes in Patients with Hepatocellular Carcinoma

Aims and background

Hepatocellular carcinoma (HCC) is one of the most common cancers in Asia. Immunological mechanisms are thought to play an important role in the control of tumor progression. The immune responses in HCC patients are poorly understood. In the present study, the proliferation and cytotoxic functions of lymphocytes from tumor tissues and peripheral blood of HCC patients were analysed. Simultaneously, the microcultures were phenotyped in order to determine the involvement of different lymphocyte subsets in mediating the cytotoxic function.

Methods

The frequencies of proliferating and cytotoxic lymphocytes from three tumor tissues and peripheral blood from ten HCC patients and nine healthy individuals were assessed by limiting dilution microculture analysis. These microcultures were phenotyped by single and dual color flow cytometry using monoclonal antibodies specific for CD4, CD8, CD56 and HLA-DR markers.

Results

The precursor frequencies of both proliferating and cytotoxic lymphocytes were found to be comparable in the peripheral blood of HCC patients and healthy individuals. Compared to peripheral blood, a marked reduction in the precursor frequencies of proliferating and cytotoxic lymphocytes was observed in the tumor tissues of HCC patients. In the tumor tissues, a significantly higher frequency of cytotoxic T cells compared to natural killer cells was observed. Dual color flow cytometric analysis revealed increased percentages of CD8+ HLA-DR+ lymphocytes compared to CD4+ HLA-DR+ cells in the tumor tissues.

Conclusions

Our results suggest that depressed immune responses at the tumor site might be responsible for the escape of tumor cells from the immune surveillance of the host.

Primary biliary cirrhosis: solving the enigma

Primary biliary cirrhosis (PBC) is a chronic cholestatic liver disease, most commonly affecting female patients between 40 and 60 years of age. Patient sera present autoantibodies against mitochondrial antigens (AMA) and elevated serum IgM. Histologic studies demonstrate progressive destruction of small- and medium-sized intrahepatic bile ducts and, ultimately, liver cirrhosis. The precise mechanisms leading to selective destruction of such biliary epithelial cells are still unknown, although a number of immunomediated pathways have been proposed. Genetic background is critical in determining susceptibility to the disease, although no clear association with haplotypes of the major histocompatibility complex has been identified. Molecular mimicry by either infectious agents or xenobiotics has been proposed as a means of breaking tolerance in genetically predisposed individuals, thus leading to the onset of PBC. In this review, available data and current theories regarding the immunomediated pathogenesis of PBC will be described.

Mitochondrial antigens as targets of cellular and humoral auto-immunity in primary biliary cirrhosis

Several factors point toward an auto-immune pathogenesis for primary biliary cirrhosis(PBC), mostly based on the presence of serum auto-antibodies to mitochondrial antigens(AMAs) and autoreactive T cells (both helper and cytotoxic). Interestingly, epitopes recognized by AMA and T-cell clones are located within overlapping areas of the antigens. Moreover,a role for an imbalance in cytokine pattern and for natural-killer lymphocytes has also been proposed. Despite several experimental reports, no clear evidence is available regarding the interaction of these factors leading to bile duct destruction. This article reviews the current reports regarding the auto-immune reaction against mitochondrial auto-antigens in PBC.

The enigma of primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is a chronic cholestatic disease characterized by a striking predominance in female patients (with most cases diagnosed between ages 40 and 60 yr) as well as serum auto-antibodies to mitochondrial antigens, elevated serum immunoglobulin M,progressive destruction of intrahepatic bile ducts, and, ultimately, liver cirrhosis and failure(1). The precise mechanisms leading to selective destruction of biliary epithelial cells lining intrahepatic bile ducts are still unknown, although numerous immunomediated pathways have been proposed. Genetic background appears to be important in determining susceptibility to the disease (2), but no clear association with alleles in the major histocompatibility complex has been identified. Molecular mimicry either by infections (3) or xenobiotics (4) has been proposed to be capable of breaking tolerance in genetically predisposed individuals, thus leading to onset of PBC. This article describes and discusses the available data regarding the immunomediated pathogenesis of PBC (with particular attention to auto-antibodies and autoreactive T-cells) and presents the recent evidence indicating a role for either xenobiotic chemicals or novel infectious agents in the induction of the disease.

Genes and (auto)immunity in primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is a chronic autoimmune cholestatic liver disease most commonly encountered in postmenopausal women; it is characterized by high-titer serum autoantibodies to mitochondrial antigens, elevated serum IgM, progressive destruction of intrahepatic bile ducts, and ultimately liver cirrhosis and failure. The cytopathic mechanisms leading to the selective destruction of intrahepatic cholangiocytes are still largely unknown. The current theory on the pathogenesis of PBC indicated that environmental factors might trigger autoimmunity in genetically susceptible individuals. In fact, genetic predisposition is critical to disease onset and progression, yet peculiar among autoimmune diseases, as indicated by the lack of a strong association with major histocompatibility complex haplotypes. Further, the recently reported concordance rate among monozygotic twins strengthens the importance of genetic factors, while also indicating that additional factors, possibly infectious agents or xenobiotics, intervene to trigger the disease. In this review, the available data regarding the genetic factors associated with PBC susceptibility and progression, as well as the available evidence regarding the immunomediated pathogenesis of PBC, will be critically illustrated and discussed.

Immunohistochemical differences in the portal tract and acinar infiltrates between primary biliary cirrhosis and autoimmune cholangitis

BACKGROUND

Antimitochondrial antibody-negative primary biliary cirrhosis, or autoimmune cholangitis, may be indistinguishable clinically and histologically from antimitochondrial antibody-positive primary biliary cirrhosis.

AIMS

We aimed to compare the phenotypic markers of the portal and acinar infiltrates in autoimmune cholangitis and antimitochondrial antibody-positive primary biliary cirrhosis.

PATIENTS AND METHODS

Formalin-fixed, paraffin-embedded liver sections were identified from 32 patients with a clinical and histological diagnosis of primary biliary cirrhosis. Thirteen were antimitochondrial antibody-negative (autoimmune cholangitis group) and 19 were antimitochondrial antibody-positive. The groups were well matched for age, histological stage, liver biochemistry and drug treatment. Immunohistochemical staining was performed using monoclonal antibodies against CD3 (pan T cell), CD8 (cytotoxic), CD45RO (memory), CD45RA (naive), CD68 (macrophages) and against the secreted form of eosinophilic cationic protein (EG2).

RESULTS

In autoimmune cholangitis, both portal and acinar CD3 cell counts were significantly higher than in antimitochondrial antibody-positive primary biliary cirrhosis (median portal count 421 vs 257 cells/graticule, P< 0.03; median acinar count 18 vs 9 cells/graticule, P< 0.02). There were no differences between the groups in portal or lobular CD8, CD45RO, CD45RA, CD68 or EG2. Of the total group (antimitochondrial antibody positives and negatives), there were significantly more CD45RA cells in early (stage 1) compared with cirrhotic (stage 4) disease (median 19.3 vs 14 cells/graticule, P< 0.03). EG2 staining was found in eight of the 32 sections overall, but not in the patients with stage 1 disease (P< 0.04).

CONCLUSION

CD3 counts are higher in autoimmune cholangitis than in antimitochondrial antibody-positive primary biliary cirrhosis in both portal and acinar areas. However, there are no significant differences in memory/naïve T-cell subsets between both conditions and, in both, loss of naive T lymphocytes and secretion of eosinophilic cationic protein occur with disease progression. This implies that the effector pathways of bile duct destruction are similar in autoimmune cholangitis and primary biliary cirrhosis.

Immunopathogenesis of cholestatic autoimmune liver diseases

Primary biliary cirrhosis and primary sclerosing cholangitis are well recognized chronic cholestatic liver diseases that are considered to have an autoimmune basis. Recent progress in the study of autoimmune liver diseases has improved the recognition and characterization of these conditions. An important component of this progress has been the identification of liver disease-associated autoantibodies and their respective target antigens, and the development of specific assays for these autoantibodies. In addition, some nonhumoral immunological findings imply an involvement of specific immunopathogenic mechanisms in the development of these conditions. Furthermore, immunogenetic factors associated with increased susceptibility to some of these diseases have been identified. This article reviews the most relevant information relating to the postulated autoimmune pathogenesis of these diseases, with special emphasis on their associated humoral and cellular immunological abnormalities and immunopathogenetic factors. Some of the remaining important unresolved issues relating to the pathogenesis of these diseases, that need to be addressed in further research, are highlighted.

Detection of a soluble form of the human adhesion receptor lymphocyte function-associated antigen-3 (LFA-3) in patients with chronic liver disease

BACKGROUND/AIMS

Multiple immune functions, such as cytotoxic reactions, B cell differentiation, and monocyte activation, are mediated via the adhesion receptor/ligand pairs CD2/lymphocyte function-associated antigen(LFA)-3 and LFA-1/ intercellular adhesion molecule(ICAM)-1. Since soluble forms of LFA-3 (sLFA-3) and ICAM-1 (sICAM-1) can interfere with these functions, we asked whether increased levels of sLFA-3 can be found in patients with different forms of chronic liver disease and/or hepatocellular carcinoma.

METHODS

sLFA-3 was measured in sera from 84 patients with chronic liver disease (39 with chronic viral liver disease, 30 with autoimmune liver disease, 12 with alcoholic cirrhosis, 3 with other causes of cirrhosis), 24 patients with hepatocellular carcinoma (15 with and 9 without cirrhosis), and 61 normal controls. From 36 of the patients with liver cirrhosis, arterial and hepatic venous serum samples were simultaneously obtained and tested for sLFA-3 and sICAM-1.

RESULTS

In comparison to controls, sLFA-3 levels were elevated in patients with liver cirrhosis due to autoimmune liver disease (p < 0.0001) and viral liver disease (p = 0.001), but not in patients with alcoholic cirrhosis. Increased sLFA-3 levels were also found in patients with hepatocellular carcinoma and liver cirrhosis. However, sLFA-3 was not significantly elevated in sera from patients with autoimmune liver disease, viral liver disease, and hepatocellular carcinoma without concomitant liver cirrhosis. No difference was found between arterial and hepatic venous serum levels of sLFA-3 and sICAM-1. sLFA-3 levels correlated positively with aspartate transaminase, alkaline phosphatase, bilirubin, sICAM-1, and inversely with albumin and cholinesterase.

CONCLUSIONS

Taken together, sLFA-3 serum concentrations of patients with liver cirrhosis due to autoimmune liver disease or viral liver disease and of patients with hepatocellular carcinoma and cirrhosis are significantly increased compared to controls. Elevated sLFA-3 and sICAM-1 levels might reflect the generalized inflammation in cirrhosis and by interference with cell-cell interactions sICAM-1 and sLFA-3 may limit the extent of inflammation.

Limiting dilution analysis of proliferating and cytotoxic lymphocytes in the peripheral blood and tumours of oral cancer patients

Frequencies of proliferating and cytotoxic lymphocytes from the peripheral blood and tumour tissue of oral cancer patients and healthy individuals were monitored using limiting dilution analysis. Significantly lower precursor frequencies of proliferating lymphocytes were observed in the peripheral blood and tumour tissue of oral cancer patients. A high frequency of natural killer (NK) cells but low cytotoxic T lymphocytes (CTL) was observed in the peripheral blood compartment of oral cancer patients as compared to healthy individuals. A marked reduction in both NK and CTL frequencies in the tumour tissue compared to the peripheral blood was observed. In the tumour tissues, increased percentages of activated CD4+ lymphocytes as compared to CD8+ lymphocytes were observed. Our results suggest that impaired proliferative and cytotoxic potential of tumour infiltrating lymphocytes may play an important role in the escape of tumour cells from the immune system.

Improvement of peripheral blood lymphocyte subsets in primary biliary cirrhosis after ursodeoxycholic acid therapy

Immunological abnormalities frequently observed in patients with primary biliary cirrhosis are considered to be related to the pathogenesis of this disease. We performed a prospective trial to evaluate whether immune mechanisms play a role in the effectiveness of ursodeoxycholic acid (UDCA) therapy. Fifteen female patients with primary biliary cirrhosis were followed for 1 year and were then treated with UDCA (600 mg/day) for another year. Laboratory tests, including peripheral blood lymphocyte subsets assessed by dual colour fluorescence analysis using monoclonal antibodies against respective T cell markers, were evaluated at the beginning of the study, at the start of therapy and at the end of therapy. In primary biliary cirrhosis, the proportion of cytotoxic T cells, suppressor inducer T cells and alpha beta-receptor bearing T cells were significantly lower than in healthy controls. No significant changes were observed in the proportions during the year before the therapy. These reductions, however, recovered to normal ranges after 1 year of UDCA therapy. These changes were associated with an improvement in the serum levels of aspartate aminotransferase, alkaline phosphatase, gamma-globulin and IgM. The close correlation between the improvement in the imbalance of lymphocyte subsets after the therapy and the clinical status suggests that an immunological process may play a role in the effectiveness of therapy in primary biliary cirrhosis.

The expression of IL-2, IL-4 and interferon-gamma (IFN-gamma) mRNA using liver biopsies at different phases of acute exacerbation of chronic hepatitis B

To investigate the hypothesis that Th1 phenotype cytokines are associated with the increasing activity of hepatitis and Th2 phenotype cytokines with decreasing activity in the liver of chronic viral hepatitis, expressions of the mRNA of the cytokines IL-2, IFN-gamma and IL-4 in the liver of 23 patients with chronic hepatitis B were investigated by reverse transcription polymerase chain reaction. Patients were divided into three groups according to the phase of acute exacerbation of hepatitis as increasing (n = 9), decreasing (n = 8), and stable phase (n = 6). Both IL-2 and IFN-gamma mRNA were preferentially expressed in increasing phase than in decreasing phase (P < 0.01, P < 0.05, respectively) and associated with the high serum alanine aminotransferase (ALT) level. On the other hand, IL-4 mRNA was detected in decreasing phase with significant frequency compared with increasing phase (P < 0.05). However, expression of IL-4 mRNA was not associated with serum ALT level. Our results suggest that Th1 phenotype cytokines up-regulate and Th2 phenotype cytokines down-regulate the liver inflammation of chronic viral hepatitis.

HLA DRB4 0101-restricted immunodominant T cell autoepitope of pyruvate dehydrogenase complex in primary biliary cirrhosis: evidence of molecular mimicry in human autoimmune diseases

We established six T cell clones specific for pyruvate dehydrogenase complex (PDC)-E2 peptides from four different patients with primary biliary cirrhosis using 33 different peptides of 17-20 amino acid residues corresponding to human PDC-E2 as stimulating antigens. The minimal T cell epitopes of these six T cell clones were all mapped to the same region of the PDC-E2 peptide 163-176 (GDLLAEIETDKATI), which corresponds to the inner lipoyl domain of PDC-E2. The HLA restriction molecules for this epitope were all identified as HLA DRB4 0101. The common essential amino acids of this epitope for these T cell clones were E, D, and K at positions 170, 172, and 173, respectively; other crucial amino acids for this epitope differed in each T cell clone. In addition, the alanine-substituted peptides at positions 170 and 173, but not 172, inhibited the proliferation of all T cell clones induced by the original peptide of human PDC-E2 163-176, indicating that amino acid D at position 172 is a critical MHC-binding site for all T cell clones tested. Interestingly, all T cell clones reacted to PDC-E2 peptide 36-49 (GDLIAEVETDKATV), which corresponds to the outer lipoyl domain of human PDC-E2. Furthermore, one T cell clone cross-reacted with exogenous antigens such as Escherichia coli PDC-E2 peptide 31-44/134-147/235-248 (EQSLITVEGDKASM), which has an EXDK sequence. This is a definite demonstration of the presence of molecular mimicry at the T cell clonal level in human autoimmune diseases. It is also considered possible to design peptide-specific immunotherapy based on the findings of T cell autoepitopes in primary biliary cirrhosis.

T cell autoreactivity against a 28 kD biliary protein (B1-p28) in primary biliary cirrhosis

BACKGROUND/AIMS

Cellular immune responses against biliary epithelial cells are important in understanding the pathogenesis of primary biliary cirrhosis. We previously reported a biliary antigen B1 which stimulated peripheral T lymphocytes of primary biliary cirrhosis as a possible, non-mitochondrial target of biliary epithelial cells. Further characterization of B1 was performed.

METHODS

To confirm localization of B1 in biliary epithelial cells, a mouse monoclonal antibody was raised against B1. As B1 could be separated into two main components by SDS-PAGE under reducing condition, these components were individually cut out from Western blots and converted into antigen-bearing particles for a proliferation assay to detect the antigenic component responsible for stimulating lymphocytes. The relation of this proliferation to HLA DR antigens was also analyzed.

RESULTS

Immunohistochemically, B1 was shown to be specifically expressed on biliary epithelial cells of human liver tissue. Of two components from B1 under reducing condition, prominent proliferation against B1-p28, a 28 kD component of B1 was detected in primary biliary cirrhosis. The reactivities were significantly higher than chronic liver diseases (p < 0.001) or normal controls (p < 0.001). Furthermore, high responders to B1-p28 were observed frequently in primary biliary cirrhosis patients with HLA DR8 (p < 0.02), which was susceptible to the development of primary biliary cirrhosis.

CONCLUSIONS

These data suggest B1-p28 expressed on biliary epithelial cells is a candidate for the target antigen of primary biliary cirrhosis in addition to mitochondrial autoantigens. Further characterization of B1-p28 may provide new insight into the autoimmune mechanisms of primary biliary cirrhosis.

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.

T cell recognition of hepatitis B and C viral antigens

The outcome of hepatitis B and C heavily depends on the appropriate virus specific T cell response. Both CD8+ and CD4+ T lymphocytes do not recognize native viral proteins but processed peptides bound to MHC class I and class II, respectively. For therapeutical intervention aimed at T lymphocytes in chronic carriers as well as for the development of new vaccines, a precise identification of immunodominant epitopes, which can be recognized by a majority of patients, is necessary. Biological features of certain viral antigens have been partly characterized in animal models, but with the availability of modern molecular technology it is possible to extend these findings to the human system. The identification of anchor residues and motifs in peptides, which are essential for binding to certain MHC class I and class II molecules, allows the prediction of MHC allele-specific epitopes within viral proteins. By the use of synthetic peptides and vaccinia expression vectors, several epitopes for cytotoxic and helper T lymphocytes have been identified in HBV and HCV antigens. In HBV infection cytotoxic T lymphocytes recognize epitopes within the polymerase protein, the envelope protein and the nucleocapsid. In HCV cytotoxic epitopes have so far been identified within the nucleocapsid, E1, E2 and NS2. Since virus specific CD8+ T lymphocytes lyse virus infected cells in vitro and seem to play an important role for viral elimination in vivo, activation of virus specific effector cells may be achieved by immunizing chronically infected patients with the MHC-allele-specific peptides. Epitopes for CD4+ T lymphocytes have been demonstrated in the majority of HBV- and HCV-proteins. Different subsets of CD4+ T lymphocytes influence the course of infection by the production of lymphokines which either support antibody production by B cells or cellular antiviral effector mechanisms. In acute and chronic HBV infection the HBcAg/HBeAg-specific T cell response is closely correlated to viral elimination and the occurrence of anti-HBe- and anti-HBs antibodies. In HCV infection the CD4+ T cell response appears to be more heterogenous, and better functional characterization of the CD4+ response to immunodominant peptide epitopes in association with certain disease stages is required. Since T cell activation, the resulting effector functions and binding of the peptide to the HLA-molecule mainly depend on the peptide structure, viral mutations leading to amino acid changes may contribute to T cell non-responsiveness or an inappropriate T cell response.(ABSTRACT TRUNCATED AT 400 WORDS)

Immunohistochemical phenotyping of liver macrophages in normal and diseased human liver

The phenotypical heterogeneity of human liver macrophages was analyzed with monoclonal antibodies that recognize antigens specific for the monocyte-macrophage lineage. Most liver macrophages in normal and diseased liver were positive for CD68, whereas fewer matured macrophages were detected by 25-F9. Comparative staining of mirror sections revealed some to be doubly positive and others to be singly CD68 positive. Quantitative analysis confirmed the difference, suggesting heterogeneity of maturation in liver macrophages. Most liver macrophages in the normal liver were negative for CD14, a receptor for lipopolysaccharide and lipopolysaccharide-binding protein complexes. Liver macrophages in liver diseases were activated to express CD14 at varying degrees and were involved in the clearance of lipopolysaccharide-lipopolysaccharide-binding protein complexes. Fc gamma RI, a receptor for monomeric IgG that is involved in antibody-mediated cell cytotoxicity, was negative in the normal liver, but was expressed in liver macrophages at inflammatory sites (e.g., in piecemeal and focal necrosis) in diseased livers. Fc gamma RII was expressed in most liver macrophages, as well as in sinusoidal endothelial cells; Fc gamma RIII was expressed in a smaller number of liver macrophages. Expression of Fc gamma RII and Fc gamma RIII was increased in chronic active hepatitis. These results suggest that liver macrophages are heterogeneous in maturation and function and that they are activated in liver diseases as shown by the novel expression of CD14 and Fc gamma RI. The restricted expression of Fc gamma RI indicates that Fc gamma RI-positive macrophages, in cooperation with cytotoxic T lymphocytes, may play an important role in liver cell injury through antibody-mediated cell cytotoxicity.

Phenotypical analysis and cytokine release of liver-infiltrating and peripheral blood T lymphocytes from patients with chronic hepatitis of different etiology

Cytokines released by infiltrating T cells may contribute to the hepatic injury in chronic hepatitis. Therefore, we characterized peripheral blood- and liver-infiltrating T cells from patients with chronic hepatitis of different etiology and determined the T cell phenotypes and the cytokine release. Liver tissue and peripheral blood-derived T cells from patients with autoimmune hepatitis and primary biliary cirrhosis predominantly expressed CD4-molecules and the alpha- and beta-chains of the T cell receptor (TCR). In chronic viral hepatitis B and C, liver- and blood-derived T cells were preferentially CD8+ T cells expressing the alpha beta TCR. Mitogenic stimulation with irradiated Daudi lymphoma cells and phytohemagglutinin led to a strong release of interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha) and interleukin-2 (IL-2) by T cells in patients with chronic hepatitis and in healthy controls. T cells from patients with primary biliary cirrhosis and some patients with autoimmune hepatitis showed a significantly higher secretion of interleukin-4 (IL-4) and interleukin-10 (IL-10) than T cells from patients with chronic viral hepatitis or healthy controls. Histologic inflammatory activity did not correlate with the amount of cytokines released after mitogenic activation. In conclusion, liver tissue and peripheral blood T cells of patients with autoimmune hepatitis and primary biliary cirrhosis were dominated by CD4+ TCR alpha beta+ T helper/inducer cells, whereas in chronic viral hepatitis an enrichment of CD8+ TCR alpha beta + cytotoxic/suppressor T cells was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Defective proliferation and regulatory function of CD4+ T cells bearing Leu-8 homing receptor in primary biliary cirrhosis. Phorbol myristate acetate enhances T-cell function

The majority of circulating CD4+ T cells express the Leu-8 peripheral lymph node homing receptor, and these cells have previously been shown to have suppressor-inducer and suppressor function. In the present study, it was found that CD4+, Leu-8+ T cells from patients with primary biliary cirrhosis (PBC) have a significantly (P < 0.01) lower proliferative response when stimulated with phytohemagglutinin (PHA), concanavalin A (Con A), or pokeweed mitogen (PWM) compared to normal controls. The proliferative response of CD4+, Leu-8- T cells was similar in patients and controls. However, the proliferative responses of CD4+, Leu-8+ from patients with PBC was normal when cells were stimulated with PHA, Con A, anti-CD3 monoclonal antibody, or ionomycin in combination with phorbol myristate acetate (PMA). CD4+ T cells from patients with PBC mediated normal helper function for PWM-stimulated immunoglobulin synthesis at high T/B ratios and their regulatory function was similar to that of normal CD4+ T cells that had been irradiated to inactivate their suppressor activity. When CD4+ T cells from patients with PBC were precultured with the combination of Con A and PMA, they mediated potent inhibitory activity similar to that of normal CD4+ T cells. Thus, CD4+, Leu-8+ T cells from patients with PBC have a defect of proliferation and suppressor function that is reversed by coculture with PMA. This finding suggests that impairment of a PMA-inducible lymphocyte activation pathway contributes to abnormal lymphocyte function in PBC.

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)

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)

Intercellular adhesion molecule-1 and MHC antigens on human intrahepatic bile duct cells: effect of pro-inflammatory cytokines

Human intrahepatic biliary epithelial cells were isolated from the livers of patients with primary biliary cirrhosis and from normal livers and established in primary culture. The in vitro expression of intercellular adhesion molecule-1, HLA class I, and HLA class II on biliary epithelial cells was studied in response to tumour necrosis factor-alpha (0-500 U/ml), interferon-gamma (0-500 U/ml), and interleukin-1 (0-5 U/ml) by immunohistochemical staining and a semiquantitative scoring system validated by spectrophotometry and previously validated by laser confocal microscopy. The non-stimulated expression of intercellular adhesion molecule-1 and HLA class II was higher on cells derived from the primary biliary cirrhosis liver than on cells from normal liver, a difference not seen with HLA class I expression. A statistically significant increase in intercellular adhesion molecule-1 expression was seen with all three cytokines in cells derived from both primary biliary cirrhosis and normal liver. Increase in HLA class I expression was seen only with interleukin-1 5 U/ml for cells derived from both normal and diseased liver. Increase in HLA class II expression was seen only with interferon-gamma 500 U/ml for cells derived from diseased liver and with interleukin-1 5 U/ml for cells derived from both diseased and normal liver. These data show that pro-inflammatory cytokines increase expression of intercellular adhesion molecule-1, HLA class I, and HLA class II on human intrahepatic biliary epithelial cells in vitro and are consistent with the hypothesis that these locally acting factors may play a part in the pathogenesis of immune mediated disorders such as primary biliary cirrhosis in which immune mediated bile duct damage occurs.

Autoreactive liver-infiltrating T cells in primary biliary cirrhosis recognize inner mitochondrial epitopes and the pyruvate dehydrogenase complex

Primary biliary cirrhosis (PBC) is characterized by lymphoid infiltrates in the portal tracts of the liver and the occurrence of antimitochondrial autoantibodies in serum directed against components of the pyruvate dehydrogenase complex and the other alpha-keto acid dehydrogenase complexes. These enzymes are located on the inner mitochondrial membrane. The destruction of the biliary tract in PBC is thought to be mediated by autoreactive liver-infiltrating T cells exerting cytotoxic activity or releasing certain lymphokines. In this study the reactivity of liver infiltrating T cells was shown to a bovine pyruvate dehydrogenase complex (PDH), a purified E2 subunit (PDH-E2) and a crude preparation of human liver mitoplasts (HLM), i.e. mitochondria depleted of their outer membranes. Peripheral blood lymphocytes (PBL) from 11 of 15 patients (73.3%) with PBC showed a HLA class II-restricted proliferative response to the PDH complex whereas PBL from patients with chronic viral hepatitis, autoimmune hepatitis or extrahepatic cholestatic icterus (n = 20) and healthy controls (n = 5) did not. In addition 13 of 15 PBL from patients with PBC (86.6%) and three of nine PBL from patients with autoimmune hepatitis (33.3%) reacted with the crude HLM preparation whereas no reactivity was found with PBL from eight patients with chronic viral hepatitis, three patients with extrahepatic cholestasis or five healthy controls. Clonal analysis of 115 liver-infiltrating T cells derived from two diagnostic liver biopsies of patients with PBC revealed a predominance of activated CD4+CD8- T helper cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Increased frequency of CD8+ CD45R0+ memory T lymphocytes in acute hepatitis B virus infection

CD8+ lymphocytes of the memory subset (= CD45R0+) encompass antigen-specific effector cells, which are believed to be decisive for virus elimination in several viral infections. To determine whether this can be extended to HBV infection naive and memory T cells were studied among CD(4+)- and CD(8+)-lymphocytes and used monoclonal antibodies in two-color flow cytometric analysis to quantitate functional T cell subsets in peripheral blood of patients with acute hepatitis B (n = 11), chronic hepatitis B (n = 24) and healthy individuals (n = 26). Compared to CD4+ populations of healthy individuals the number of total CD4+ lymphocytes in patients with both acute or chronic hepatitis was significantly reduced. In contrast CD8+ cells did not significantly change in either acute and chronic hepatitis. Analysis of naive and memory subsets demonstrated, however, a significant rise in CD45R0+ memory cells from 5 to 15% (70% of all CD8+ cells) in acute hepatitis. These changes within the CD8+ population were, however, restricted to the acute phase of hepatitis in that the frequency of CD8+CD45R0+ decreased within weeks post infection. Furthermore, patients with chronic hepatitis did exhibit normal values of CD8+ memory cells (30% of all CD8+ cells). These findings suggest that enrichment of CD8+CD45R0+ memory cells reflects an accumulation of functional effector cells, which may be specifically activated by viral antigens and determine the outcome of infection.

Occurrence of primary biliary cirrhosis, CREST syndrome and Sjögren's syndrome in a patient with HTLV-I-associated myelopathy

We report the occurrence of three autoimmune diseases (primary biliary cirrhosis, CREST syndrome and Sjögren's syndrome) in a patient with HTLV-I-associated myelopathy (HAM). The patient had the depressed cell-mediated immune responses but the infiltration of CD8-T cells was found in the cerebrospinal fluid and liver. The clinical and immunological features of this case are similar to those of chronic graft-versus-host disease.

Clonal expansion of lymphocytes from oral lichen planus lesions

Lymphocytes were extracted from 11 biopsy specimens of oral lichen planus (OLP) by collagenase digestion, and cell lines were expanded with repetitive cycles of stimulation (with phytohaemagglutinin) and rest in media supplemented with interleukin 2. Four OLP lines contained a majority of CD3+CD4-CD8+ cells, in six lines the CD4:CD8 ratio was between 1 and 2, and in one line the CD4:CD8 ratio was 5:1. Limiting dilution of nine lines at 0.3 and 1.0 cells/well resulted in viable wells (putative clones) with plating efficiencies ranging from 0.0 to 18.1 percent and 0.0 to 22.2 percent respectively. The majority of clones were CD3+CD4-CD8+alpha beta+gamma delta-, although three clones were CD3+CD4+CD8-alpha beta+gamma delta- and one clone was CD3+CD4-CD8- and expressed the gamma delta T cell receptor. T cell clones derived from lymphocytes extracted from OLP lesions may be generated and maintained in culture providing opportunity for their further phenotypic and functional characterisation. This strategy may facilitate the identification of a putative oral lichen planus-specific antigen and indicate the frequency of lichen planus-specific T cells within lesions of OLP.

Spontaneous occurrence of autoimmune cholangitis in senescent mice

The biliary lesions that developed spontaneously in senescent female C57BL/6NCrj mice were investigated. Degeneration of the bile duct epithelium was observed in 12 of 13 mice (92%), destruction of bile duct epithelial cells was seen in six of 13 mice (46%) and chronic non-suppurative destructive cholangitis was found in three of 13 mice (23%). The biliary lesions were characterized by prominent round cell infiltrates in the portal areas. Extra-hepatic lesions such as sialoadenitis were observed in six mice (46%) and pancreatis in seven (53%). IgM class antipyruvate dehydrogenase antibody was positive in one of three C57BL/6NCrj mice not given anti-Lyt 2 antibody and in three of six C57BL/6NCrj mice injected with anti-Lyt 2 antibody. These lesions were not observed in male C57BL/6NCrj mice, young female C57BL/6NCrj mice, or ICR mice. However, by transferring the splenic cells of senescent female C57BL/6NCrj mice to 6 week old females, the biliary lesions could be transferred at the rate of 6/9. The lymphocytes infiltrating in the bile ducts were CD8 positive lymphocytes. Moreover, in the ultrastructural immunocytochemical analysis of lymphocytes infiltrating bile duct epithelia, CD8 positive lymphocytes often formed broad contacts with the epithelial cells. The biliary lesions developing spontaneously in these mice are similar to those found in human primary biliary cirrhosis.

Phenotypic and functional characteristics of lymphocytes isolated from liver biopsy specimens from patients with active liver disease

Liver-derived lymphocytes were isolated from 73 liver biopsy specimens obtained from patients with chronic active liver disease and from six samples of normal liver. Mean absolute numbers (+/- S.E.M) of liver-derived lymphocytes recovered from needle biopsy specimens by mild enzymatic digestion of the liver tissue varied from 0.7 +/- 0.3 x 10(3)/mm3 in allografts being rejected to 8.9 +/- 0.9 X 10(3)/mm3 in chronic non-A, non-B hepatitis. By two-color flow cytometry, T lymphocytes (CD3+) were the major liver-derived lymphocyte population in all biopsy specimens. The mean CD4/CD8 ratio (0.6 +/- 0.2) was similar for liver-derived lymphocytes obtained from samples of normal or diseased liver. However, activated (human leukocyte antigen DR+) T cells were significantly (p less than 0.05) increased in liver-derived lymphocytes obtained from liver disease specimens than they were in samples from normal livers. Natural killer cells were less numerous than T cells in specimens obtained from diseased livers, with the mean natural killer/T cell ratio ranging from a low of 0.1 in allograft rejection to a high of 0.8 +/- 0.3 in primary sclerosing cholangitis. Liver-derived lymphocytes isolated from diseased liver contained significantly fewer (p less than 0.05) CD3-CD56+ or CD56+CD16-natural killer cells than did those obtained from normal liver samples. Natural killer activity was consistently detectable in liver-derived lymphocytes obtained from specimens of normal or diseased livers. Moreover, natural killer activity in the liver did not differ significantly from that in either normal or patient peripheral blood.(ABSTRACT TRUNCATED AT 250 WORDS)

T lymphocytes from patients with primary biliary cirrhosis produce reduced amounts of lymphotoxin, tumor necrosis factor and interferon-gamma upon mitogen stimulation

Primary biliary cirrhosis (PBC) is considered an autoimmune disease characterized by destruction of small intrahepatic bile ducts by lymphocytes. Altered functions of these lymphocytes might reflect an abnormal immune response leading to tissue damage. We investigated lymphokine secretion by mitogen-stimulated T lymphocytes from the liver biopsies of patients with PBC and for comparison also peripheral blood. In PBC, diminished synthesis of lymphotoxin (TNF beta), tumor necrosis factor (TNF alpha) and interferon-gamma (IFN gamma) was found both in T-cell lines from liver tissue and in peripheral blood. The reduction was most prominent for TNF beta in early histological stages of PBC, and appeared to be a stable phenomenon when T cells were tested after long-term tissue culture. Analysis of mRNA levels indicates a possible link between reduced TNF beta production and a defect in interleukin-2 transcription. The data suggest that diminished lymphokine production in patients with PBC may play an important role in the immunopathogenesis of this disease.

Hepatitis B virus antigen-specific T-cell activation in patients with acute and chronic hepatitis B

Since the hepatitis B virus is noncytopathic, it is generally believed that the individual specific immune response determines the course of infection. The lack of data about hepatitis B virus-specific T-cell reactions in acute infection led us to investigate the specific cellular immune response of infected individuals in terms of proliferation, and gamma-interferon and lymphotoxin production. Our results demonstrate that peripheral blood mononuclear cells (PBMNC) from patients with acute and chronic hepatitis B respond weakly to HBsAg. In contrast, patients with acute hepatitis show a vigorous response to the nucleocapsid antigen (HBcAg) in terms of proliferation and lymphokine production, while only few chronic virus carriers gave a proliferative response. Either of the antigens could activate lymphocytes to produce gamma-interferon and lymphotoxin, cytokines which may modulate antiviral immune response.

Blood and liver-infiltrating lymphocytes in primary biliary cirrhosis: increase in activated T and natural killer cells and recruitment of primed memory T cells

We used two-color and three-color flow cytometric analysis to study phenotypical activation and functional subsets of T and natural killer cells in the blood and liver tissue of patients with primary biliary cirrhosis, other chronic liver diseases and the blood of healthy subjects. The changes in blood lymphocyte phenotype in patients with primary biliary cirrhosis and other chronic liver diseases were similar and comprised elevated relative or absolute numbers of activated human leukocyte antigen-DR + T subset (CD4+ and CD8+) cells and DR+ natural killer-like (CD16+) cells. B cell (CD19+) numbers were normal. In primary biliary cirrhosis a selective reduction in T cells of suppressor-inducer (CD45RA + CD4 + ) type was registered. The human leukocyte antigen-DR expression among CD4+ T cell subsets was investigated further in primary biliary cirrhosis and healthy controls using triple antibody flow cytometric analysis. Phenotypical cell activation was confined to helper T cells of the primed, memory (CD45RO + CD4+) type. The decrease in suppressor-inducer T cells in primary biliary cirrhosis was paralleled by a reciprocal increase in primed memory T cells. Several significant differences were observed when blood and liver-infiltrating cells from primary biliary cirrhosis patients were compared. In the liver tissue, the CD4/CD8 ratio was decreased, the relative activation of T-subset cells and NK cells was further increased, the suppressor-inducer T subset was further depressed and the primed memory T subset was increased. The cytotoxic T-cell subset (CD11b-) dominated within the CD8+ population. In liver tissue from other chronic liver disease subjects, a lower CD4/CD8 ratio was found compared with primary biliary cirrhosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Clonal analysis of liver-infiltrating T cells in patients with LKM-1 antibody-positive autoimmune chronic active hepatitis

Autoantibodies against microsomal antigen of liver and kidney (LKM-1) are diagnostic markers for a subgroup of autoimmune chronic active hepatitis (AI-CAH). Cytochrome P450dbl, now classified as cytochrome P450 IID6, is the major antigen of LKM-1 antibodies. Immunohistological studies suggest that hepatic injury in AI-CAH is mediated by liver-infiltrating T cells. In the present study the specificity and function of liver-infiltrating T cells was analysed at the clonal level. Phenotypical characterization of 189 T cell clones isolated from four liver biopsies of LKM-1 antibody-positive patients showed an enrichment of CD4+ CD8- T cell clones proliferated specifically in the presence of recombinant human LKM-1 antigen (rLKM). This reaction was restricted to autologous antigen-presenting cells and to HLA class II molecules. In order to see whether rLKM was also recognized by peripheral blood T lymphocytes (PBL) we tested the proliferative response of PBL from several individuals. PBL from three of the four patients with LKM-1 antibody-positive AI-CAH proliferated to rLKM, whereas no response was seen with PBL from patients with LKM-1 antibody-negative chronic liver diseases and from healthy blood donors. These data demonstrate that the LKM-1 antigen is recognized by liver-infiltrating T cells in LKM-1 antibody-positive AI-CAH. For further functional characterization, liver-derived T cell clones were tested for their cytotoxic activity. In the presence of phytohaemagglutinin 24 out of 26 CD4- CD8+ but also 20 out of 63 CD4+ CD8- T cell clones lysed autologous as well as allogenic EBV-transformed B cell lines or K562 cells. Five CD4- CD8+ T cell clones lysed autologous but not allogenic B cell lines spontaneously in a HLA class I-restricted manner. Although the antigen specificity of these clones is still unknown the data show the presence of autoreactive T cells at the site of inflammation that could contribute in the pathogenesis of AI-CAH.

Primary biliary cirrhosis: paradigm or paradox for autoimmunity

Primary biliary cirrhosis has been classified as a model autoimmune disease based on striking defects in immune regulation and the presence of autoantibodies to mitochondria. Until recently the significance and definition of mitochondrial autoreactivity was unknown. Since 1987, there has been a vast improvement in the understanding and definition of the biochemical and molecular target autoantigens. The cloning of complementary DNAs for mitochondrial antigens has led to the identification of three enzymes of the 2-oxo-acid dehydrogenase family as the targets of the autoantibodies to mitochondria in patients with primary biliary cirrhosis. The major reactive autoantigen is the E2 subunit of pyruvate dehydrogenase. Immunodominant sites on pyruvate dehydrogenase E2 (autoepitopes) have been mapped and have been shown to be the site of attachment of the functionally important lipoic acid prosthetic group. The autoepitope for the other enzymes probably occupies an equivalent site on the enzyme. The availability and definition of these mitochondrial autoepitopes have allowed specific questions to be addressed relating to the processing and targeting of these autoantigens as well as further studies on mechanisms of immunopathology. Similarly, the availability of well-defined autoantigens could contribute to the development of valid animal models in addition to the already described reproduction of the biliary ductular lesions by transfer of peripheral blood lymphocytes from patients with primary biliary cirrhosis into severe combined immunodeficient mice. Such models will facilitate specific study of the role of major histocompatibility complex expression and the characterization of T-cell reactivity. Thus, primary biliary cirrhosis is a key example of significant progress in autoimmunity being made by use of recombinant DNA technology.

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 human hepatic asialoglycoprotein receptor is a target antigen for liver-infiltrating T cells in autoimmune chronic active hepatitis and primary biliary cirrhosis

Autoantibodies to the human hepatic asialoglycoprotein receptor have been found in nearly 50% of the sera of patients with autoimmune chronic active hepatitis and in 15% of patients with primary biliary cirrhosis. In this study we demonstrate that the human hepatic asialoglycoprotein receptor is also a target antigen for T cell-mediated immune responses. Peripheral blood lymphocytes of 37% (7 of 19) of patients with autoimmune chronic active hepatitis and 33% (2 of 6) of patients with primary biliary cirrhosis showed a proliferative response to highly purified human hepatic asialoglycoprotein receptor, whereas no proliferation was found with peripheral blood lymphocytes of patients with chronic viral hepatitis (0 of 13) and healthy blood donors (0 of 4). Moreover, we isolated T-cell clones from liver biopsy samples of two patients with autoimmune chronic active hepatitis and two patients with peripheral blood lymphocytes. Between 2.8% and 14.3% of these clones showed a specific proliferative response to purified human hepatic asialoglycoprotein receptor. The response was restricted to autologous antigen-presenting cells and could be blocked by monoclonal antibodies against human leukocyte antigen-DR molecules. The response of T cells to the human hepatic asialoglycoprotein receptor did not require the lectinlike activity of the asialoglycoprotein receptor. Thus the human hepatic asialoglycoprotein receptor could be identified as a major target antigen of humoral and cellular immune reactions in autoimmune-mediated liver diseases.

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.

Analysis of hepatic T lymphocyte and immunoglobulin deposits in patients with primary biliary cirrhosis

The histological findings in patients with primary biliary cirrhosis have been well-defined and are often used in the clinical staging of disease. However, it has only been with the development of reagents that phenotypically characterize the lymphoid infiltrate that attempts have been made to correlate pathophysiology with immune effector populations. Indeed, the inflammatory hepatic lesions in primary biliary cirrhosis have been described as containing CD4-positive and CD8-positive T cells. Less clear, however, have been the T cell receptors in these lesions. Further, the data on immunoglobulin deposits in hepatic lesions have been less well-defined; this deficit may be a result of the quality of polyspecific sera and difficulties in background. To address these issues, we have used a battery of well-defined monospecific and polyspecific reagents to phenotypically define the occurrence of lymphoid cells in the livers of patients undergoing transplantation. Furthermore, we have defined these same markers on T cell lines derived from liver, regional lymph node and peripheral blood. The predominant cell type in the mononuclear infiltrate is the CD3+, CD4+ T lymphocyte bearing the T cell receptor alpha beta. T cell lines from the same patients demonstrate similar findings. Of special importance, however, was the detection of CD20+ B cells and Ig+ cells in the lymphoid infiltrate. Indeed, we also readily demonstrated the presence of immunoglobulin on the surface of biliary epithelium. These data suggest that mechanisms involved in the pathophysiology of primary biliary cirrhosis may include both T cell and antibody mechanisms. The results also underscore the need to develop a functional, and not just a phenotypical, assay of the inflammatory infiltrate.

Propagation and characterization of lymphocytes infiltrating livers of patients with primary biliary cirrhosis and autoimmune hepatitis

Lymphocytes were propagated with interleukin 2 from liver tissue removed at transplantation from patients with primary biliary cirrhosis or autoimmune chronic active hepatitis. Phenotypic analysis of the cultured lymphocytes as well as the infiltrating cells in situ indicated that the culture technique did not select for a particular phenotype. Eight cultures were tested for cell-mediated lympholysis activity against a bile duct tumor line as well as a hepatocellular carcinoma line, but no specific killing was seen. In addition, no natural killer activity was detected. However, the lymphocyte cultures were able to kill the targets in a lectin-dependent cytotoxicity assay, indicating their cytolytic effector activity. Preliminary studies have demonstrated that lymphocytes extracted from hepatic tissue and hilar lymph nodes from a patient with primary biliary cirrhosis proliferated in response to autologous biliary epithelial cells. These methods might be useful in studying the pathogenesis of primary biliary cirrhosis and other liver diseases with autoimmune features.

Immunopathology of acute galactosamine hepatitis in rats

Galactosamine hydrochloride induces liver disease in rats that morphologically resembles drug-induced hepatitis in man. In this study we analyzed the character of the inflammatory reaction following the toxic damage resulting from the administration of galactosamine hydrochloride using a broad panel of monoclonal antibodies to lymphocyte subsets and macrophages. Fat-storing cells were identified with a polyclonal anti-desmin antibody. Cellular proliferation was assessed by labeling S-phase cells with the thymidine analog bromodeoxyuridine. Injection of galactosamine hydrochloride was associated with conspicuous hepatocyte necrosis and parenchymal granulocyte influx in the first 24 hr. Thereafter, mononuclear inflammatory cells predominated, mainly T lymphocytes and macrophages, with maximal numbers at 48 hr. The majority of T lymphocytes were CD8-positive cells and were located in the portal tracts and parenchyma. CD4-positive T cells were scarce and confined to the portal tracts. Proliferation of fat-storing cells paralleled hepatocyte regeneration with maximal values after 48 to 72 hr. The temporal relationship between infiltrating mononuclear cells, mainly T lymphocytes of CD8 phenotype and macrophages, fat-storing cell proliferation and hepatic regeneration suggests pathophysiological interactions between these cell types in liver injury in the rat after galactosamine hydrochloride administration.

T cell receptor gene rearrangements of T lymphocytes infiltrating the liver in chronic active hepatitis B and primary biliary cirrhosis (PBC): oligoclonality of PBC-derived T cell clones

Immunological events are involved in the pathophysiology of chronic active hepatitis as indicated from the accumulation of T lymphocytes at the site of tissue damage. We generated T cell clones from liver biopsies of 3 patients with chronic active hepatitis B and 2 patients with primary biliary cirrhosis. These T cell clones (n = 84) were analyzed by means of T cell receptor (TcR) beta gene rearrangements to determine whether the infiltrate consists of a polyclonal or oligoclonal T cell population. The vast majority (62 of 64) of T cell clones from three different patients with chronic active hepatitis B showed no identical rearrangements of the TcR beta chain genes. In marked contrast, in both patients with primary biliary cirrhosis, T cell clones established were of limited diversity. Thus 5 out of 10 and 2 out of 10 T cell clones from one patient and 3 out of 9 and 2 out of 9 T cell clones from the second patient, respectively, showed identical TcR beta gene rearrangements. These data suggest that a clonal dominance is characteristic for local T cell responses in autoimmune liver disease such as primary biliary cirrhosis whereas in virus-induced chronic active hepatitis T cell activation occurs polyclonally.

Liver-derived T cell clones in autoimmune chronic active hepatitis: accessory cell function of hepatocytes expressing class II major histocompatibility complex molecules

Thirty T cell clones were generated from T cell blasts, infiltrating the liver of autoimmune chronic active hepatitis (CAH) patients, stimulated with autologous hepatocytes expressing class II major histocompatibility complex (MHC) molecules and interleukin 2 (IL2). Sixteen clones were CD4+ and 14 were CD8+; all were CD25+ and WT31+, revealing that all cell lines expressed the alpha/beta chains of T cell receptor. Five CD4+ and 4 CD8+ T clones proliferated in response to hepatocytes expressing both class I and class II antigens. The hepatocyte recognition was MHC restricted because only class II MHC-matched hepatocytes were able to stimulate the CD4+ T clones, while only class I-matched hepatocytes stimulated CD8+ T clones, and because MoAbs to monomorphic determinants of class II antigens or to class I antigens appeared to block the response of the CD4+ and CD8+ T clones, respectively. These findings, together with the observation that autologous irradiated peripheral blood mononuclear cells (iPBMC) were unable to stimulate the clones, indicate that the response of these clones was directed to a liver membrane antigen in association with class II or class I MHC molecules on the surface of the hepatocytes. All the CD8+ T clones and 5 CD4+ T clones expressed high cytotoxic activity in a lectin-dependent cell-mediated cytotoxicity assay; 10 CD8+ and 3 CD4+ T clones also showed natural killer (NK)-like function. The cytolytic machinery was also present in those clones (both CD8 and CD4) recognizing the HLA-matched hepatocytes. All liver-derived T clones were able to produce high amounts of interferon (IFN)-gamma, as well as being capable of secreting IL2, following PHA stimulation.

Generation of biliary lesions after transfer of human lymphocytes into severe combined immunodeficient (SCID) mice

Human PBL have been reported to reconstitute B and T cells as well as human serum Ig in mice with severe combined immunodeficiency disease (SCID). To confirm these observations and attempt the transfer of an autoimmune disease to the immunodeficient animals, groups of SCID mice received an injection of PBL from patients with primary biliary cirrhosis (PBC) or from normal volunteers. By 8 wk after the injection of 10-42 x 10(6) PBL into the mice, human lymphoid cells were detected in the spleen of approximately half of the animals and all had detectable serum levels of human IgG. Moreover, the sera of SCID mice that received cells from patients with PBC contained human antimitochondrial antibodies (AMA) to dihydrolipoamide acetyltransferase, the major mitochondrial autoantigen of PBC. Histologically, a human mononuclear cell infiltrate was present around the portal areas of the liver and inflammation, bile duct atypica, and necrosis of bile duct cells were observed. While the biliary lesions in the SCID recipients of PBC cells were more severe, a mononuclear infiltrate was clearly evident in mice that received cells from normal donors, suggesting the presence of a graft-vs.-host-like disease. While these data are the first to describe an animal model with both the humoral and cellular characteristics of PBC, they also raise an interesting question regarding the preferential localization of lymphoid cells to the biliary system.

Modification of the immune response against hepatitis B virus by the human immunodeficiency virus

Hepatitis B virus and the human immunodeficiency virus are similarly transmitted. Individuals with preexisting HIV infection have a higher chance to become HBsAg carriers than do anti-HIV negative persons. Cytotoxic T cells with specificity for HBcAg, that are under the control of HBcAg-specific helper T cells, are responsible for liver injury. There is good evidence that HIV infection lowers inflammatory activity, is associated with milder liver histology, high levels of viral replication and low seroconversion rates. In addition interferon alpha therapy is less effective in anti-HIV positive subjects. The immune response against HBsAg is helper T-cell dependent and vaccination against hepatitis B is of low effectiveness. In addition, vaccination against hepatitis B may activate the HIV disease and is, therefore, presently not to be recommended.

Molecular basis of mitochondrial autoreactivity in primary biliary cirrhosis

Primary biliary cirrhosis (PBC), styled as a model autoimmune disease, has a very close association with antibodies to mitochondrial antigens. The cloning of cDNAs for mitochondrial antigens led to their identification as the three enzymes of the 2-oxo-acid dehydrogenase family which includes pyruvate dehydrogenase (PDH). The autoantigen is associated with the E2 subunit of these enzymes. PDH is the 70-74 kDa antigen previously identified by immunoblotting. An immunodominant site (autoepitope) can be mapped to a sequence of PDH-E2 which is the site of attachment of the functionally important lipoic acid prosthetic group. Here, Ian Mackay and Eric Gershwin discuss how autoantigen identification and epitope mapping has now proceeded further in PBC than in other autoimmune diseases, and will allow access to critically important questions on pathogenesis of PBC in particular and autoimmunity in general.