Lymphocytotoxicity test against rabbit hepatocytes in chronic liver diseases

Retroviral-mediated transfer and expression of hepatitis B e antigen in human primary skin fibroblasts and Epstein-Barr virus-transformed B lymphocytes

Previously, an amphotropic retroviral expression system coding for the neomycin resistance gene was developed and used to synthesize hepatitis B e antigen (HBeAg) and hepatitis B core/e antigen (HBc/eAg) in transfected mouse NIH 3T3 fibroblasts (A. McLachlan et al., 1987, J. Virol. 61, 683-692). In the present study, these transfected cell lines were infected with a helper amphotropic murine leukemia virus resulting in the production of infectious recombinant retrovirus. The recombinant retrovirus was examined for its capacity to transmit resistance to the antibiotic, G418, and to express hepatitis B virus antigens in mouse NIH 3T3 fibroblasts, human primary skin fibroblasts, and Epstein-Barr virus (EBV)-transformed B lymphocytes. A mouse NIH 3T3 fibroblast clone was generated which produced recombinant retrovirus with the capacity to transmit HBeAg expression to these murine and human cell lines. In contrast, it was not possible to transmit HBc/eAg synthesis efficiently to these cell lines by recombinant retroviral infection. The difference between the efficiencies of transmission of HBeAg and HBc/eAg expression by recombinant retroviral-mediated infection was not predicted as the expression vector coding for HBc/eAg synthesis differs only by the deletion of approximately 90 nucleotides of HBV DNA sequence from the vector coding for HBeAg synthesis.

Alcohol, cancer, and immunomodulation

There is a great deal of epidemiological evidence indicating that chronic, excessive alcohol consumption is a major risk factor for cancers in humans. However, the experimental basis for the increased cancer risk associated with alcohol intake is not clear. Since it appears that ethanol alone is not carcinogenic, ethanol effects must be explained in terms of its modifying the actions of other causal agents. Current studies indicate that ethanol and its congeners may act as tumor promoters, thereby enhancing the effect of initiating carcinogens from the environment. Available evidence also shows that ethanol is immunosuppressive. Clearly, cirrhosis due to high, prolonged alcohol intake is an indicator of the immunosuppressive effects of ethanol. It is less clear that more moderate intakes of alcohol could have as profound an effect on immune systems. However, changes do occur yielding alterations in lymphocyte sensitivity to alcohol in vitro and in cell development, as shown by increased NK cell function at low concentrations. Since other conditions, such as cytotoxic drugs which suppress cellular immune functions, are clearly associated with increased cancer risk. It is intriguing to think that prolonged exposure to ethanol-induced immunosuppression may be a cofactor in the promotion of cancer. The tumor promotion may take place via a variety of mechanisms as discussed in this paper, including reduced host defenses by direct effects of ethanol, its metabolites, and/or malnutrition. It may be beneficial to test methods for immunostimulation in prolonged alcohol abusers, where cessation of use is unsuccessful or residual immunosuppression remains, to reduce the risk of development or growth of initiated tumors.

Identification of alcohol abuse and alcoholism with biological parameters

The prevalence and incidence of heavy alcohol consumption are major problems which have been increasing in many countries in recent years. It is crucial for physicians to consistently identify early drinking problems as well as the various end disease states in order to minimize suffering and maximize recovery. This paper reviews the evolutionary development of clinical tools for detection of alcohol abuse. The focus is primarily on clinical/biochemical indicators of alcohol abuse, emphasizing but not limited to changes in hematological characteristics, liver enzyme activity, lipids, immune function factors, hormones, neurological factors, and some physically based tests. Use of test combinations and sophisticated statistical analysis of pattern changes in test batteries evidence increased diagnostic efficiency.

T lymphocyte subsets implicated in cytotoxicity in autologous hepatocytes in chronic active hepatitis patients with active viral replication

We investigated inhibitory effect of various monoclonal antibodies on T-cell-mediated cytotoxicity against autologous hepatocytes in 24 patients with hepatitis B surface antigen/hepatitis B e antigen (HBsAg/HBeAg)-positive chronic active hepatitis. A significant reduction of cytotoxicity index occurred after preincubation of T lymphocytes with anti-Leu 7 (killer-natural killer cells), D1/12 (Ia-positive cells), 5/9 (restricted helper/inducer cells), and MLR4 ("activated" and radiosensitive helper cells) monoclonal antibodies (MAb). Anti-Leu 2a (cytotoxic/suppressor cells) and anti-Leu 3a (helper/inducer cells) MAb did not affect cytotoxic activity. This finding supports the hypothesis that the T cytotoxic reaction in this in vitro system is probably due to two mechanisms: first, spontaneous cell membrane cytotoxicity sustained by anti-Leu-7-positive lymphocytes; and second, specific cytotoxicity mediated by activated Ia-positive cells. We also found that the presence of helper/inducer cells (5/9 positive) appears to be a prerequisite for the cytotoxic reaction.

Cellular cytotoxicity against autologous hepatocytes in acute and chronic non-A, non-B hepatitis

In a microcytotoxicity assay we tested lymphocyte cytotoxicity against autologous hepatocytes. The following cytotoxicity values were found (given mean +/- SEM): acute non-A, non-B (NANB) hepatitis 45.7 +/- 4.3% (n = 7), chronic NANB hepatitis 32.8 +/- 5.1% (n = 11), chronic active hepatitis B (CAH-B) 27.7 +/- 6.7% (n = 10), toxic lesions 18.1 +/- 4.2% (n = 18), controls with normal liver histology or minimal changes 4.9 +/- 2.5% (n = 8). Thus our study shows enhanced cellular cytotoxicity in acute and chronic NANB hepatitis and indicates that T cells as well as non-T cells have cytotoxic effector functions. These findings are similar to those obtained in CAH-B and suggest that cellular immune reactions play an important role in the course of NANB hepatitis. For comparison we tested cytotoxic reactions in toxic lesions. They were only moderate and well distinguishable from those observed in NANB hepatitis and CAH-B; they even may be unspecific. No correlation was seen between cytotoxicity and aminotransferase concentrations.

Kupffer cells inhibit the lymphoproliferative response to antigenic stimulation by rat hepatocytes

Sprague-Dawley rats were immunized with liver-specific protein. Kupffer cells and hepatocytes were prepared by the enzyme digestive procedure, and macrophage-depleted lymphocytes were prepared by the glass adherence method. Lymphocytes were incubated with macrophages or with Kupffer cells during the antigenic stimulation of mitomycin-C-treated hepatocytes for 90 h, and 3H-thymidine incorporation of lymphocytes was analyzed. The proliferation of lymphocytes cultured with macrophages was increased, but the proliferation of lymphocytes cultured with Kupffer cells was decreased in the rats immunized with liver-specific protein. And cytotoxicity to hepatocytes was increased after lymphocyte-Kupffer cell culture in the immunized rats. On the other hand, the proliferation of lymphocytes and cytotoxicity to hepatocytes were not significantly increased in normal rats. In the immunized rats lymphocytes cultured with macrophages showed a proliferative response to the membrane of hepatocytes, but inhibition of the lymphoproliferative response by Kupffer cells is considered to be due to destruction of hepatocytes (and thereby removal of antigen).

Occurrence and significance of IgG liver membrane autoantibodies (LMA) in chronic liver diseases of different aetiology

The prevalence of liver cell membrane antibodies (LMA) was evaluated in the sera of 124 untreated patients with various chronic liver diseases, in 17 acute hepatitis patients and in 40 normal controls by indirect immunofluorescence on rabbit hepatocytes, isolated by non-enzymatic method. The presence of LMA was compared with the presence of HBs Ag, anti-HBc and non-organ specific autoantibodies (anti-nuclear antibody, ANA; smooth muscle antibody, SMA; anti-mitochondrial antibody, AMA; liver-kidney microsomal antibody, LKM). LMA was found in 83% of autoimmune chronic active liver disease (CALD), in 47% of cryptogenic CALD and in 42% of primary biliary cirrhosis (PBC). LMA prevalence both in HBsAg positive and HBsAg negative/anti-HBc positive CALD was 11%, significantly lower than in the other three groups. In the cryptogenic group the prevalence of non-organ specific autoantibodies was significantly lower than LMA prevalence. The 35 LMA positive sera were titred to end point dilution. Autoimmune cases presented titres higher than those of all the other groups. Adsorption experiments showed that in autoimmune cases LMA fluorescence is not blocked by pre-incubation with liver antigens LSP and LP2, while a mild blocking effect was observed in some HBsAg positive cases or PBC sera. No cross-reaction with mitochondrial antigens was observed in PBC sera. LMA can still be considered a marker of autoimmune CALD only when present at high titre and without cross-reactivity with other liver antigens.

Lymphocytotoxicity against autologous hepatocytes and membrane-bound IgG in viral and autoimmune chronic active hepatitis

Membrane-bound IgG and lymphocytotoxic activity of total, T-enriched and T-depleted lymphocytes, using autologous hepatocytes have been evaluated in: (a) 31 patients with chronic active hepatitis (CAH) (six autoimmune and 25 hepatitis B virus - HBV-related); (b) five patients with inactive alcoholic cirrhosis; and (c) nine subjects with normal hepatic histology. Lymphocytotoxicity was positive in 83% of autoimmune CAH and 68% of HBV-related cases; it was confined to the T-depleted subpopulation in the first group, while it was present in both the T-enriched and T-depleted subpopulations in 81% of HBV-related cases. Membrane-bound IgG was present in 58% of group (a) and in none of the other groups. A linear pattern was found in four out of five autoimmune CAH patients with positive lymphocytotoxic activity. The autoimmune patient with lymphocytotoxic activity within the normal range did not show any membrane fluorescence. Among HBV-related CAH patients, 13 presented a granular pattern, two an associated granular and linear pattern and ten were negative. These data suggest that different lymphocytotoxic mechanisms are involved in the two forms of CAH studied.

A quantitative ultrastructural analysis of the leukocytes in contact with hepatocytes in chronic active hepatitis, with a cytochemical detection of mononuclear phagocytes

In an attempt to characterize in vivo the immune cells cytotoxic to hepatocytes in patients with chronic active hepatitis (CAH), a quantitative ultrastructural analysis of leukocytes in close contact with hepatocytes was performed in 13 patients with untreated HBsAg-negative CAH. Mononuclear phagocytes were identified by detection of endogenous peroxidase. Of the leukocytes, 8.3-4.1% were mononuclear phagocytes, 12.5-25.8% were large lymphocytes with a prominent secretory apparatus, assumed to represent mostly killer cells (T-cytotoxic cells and/or null cells), 12.2-56.8% were small lymphocytes poor in cytoplasmic organelles, and 0-45.8% were plasma cells. Patients with high serum transaminase levels had significantly more mononuclear phagocytes (P less than 0.001) and significantly fewer plasma cells (P less than 0.001) and small lymphocytes (P less than 0.001) than patients with lower disease activity. The profile of the leukocytes in contact with hepatocytes in these CAH patients suggests that mononuclear phagocyte-mediated mechanisms play an important role in hepatocyte necrosis in vivo.

Cell-mediated cytotoxicity to rabbit liver-specific lipoprotein in chronic active hepatitis

Cell-mediated cytotoxicity to 51Cr-labelled avian red blood cells coated by rabbit liver-specific lipoprotein was evaluated in 27 patients with untreated chronic active hepatitis (11 were HBsAg-positive). A significantly increased cytotoxicity was recorded in 10 of the 11 patients with HBsAg-positive chronic active hepatitis and in 13 of the 16 HBsAg-negative patients. The addition of rabbit LSP to the test system reduced to normal the cytotoxicity index in all the positive cases. Moreover, in order to evaluate the organ-specificity of cytotoxicity to rabbit LSP-coated cells, we added to the test system a macromolecular kidney protein fraction which was unable to block the cytoxicity in any of the positive cases. In 12 selected cases, which had previously shown an increased cytotoxicity to rabbit LSP-coated red blood cells, the incubation of their lymphocytes at 37 degrees C for 30 min in a plastic Petri dish resulted in the abolition of cytotoxicity. Our findings seem to indicate that cell-mediated cytotoxicity to LSP can also be detected with an antigen, not prepared from human liver. This is a further evidence that patients with chronic active hepatitis develop an immunological reactivity to not species-specific antigenic determinants in LSP.

Cytotoxicity of mononuclear cells and vulnerability of hepatocytes in alcoholic fatty liver of baboons

Mononuclear cell cytotoxicity against autologous, allogeneic and xenogeneic (rabbit) hepatocytes was investigated in nine baboons fed alcohol for 17-21 months and in nine pair-fed controls. All alcohol-fed animals developed fatty liver. Cytotoxicity of mononuclear cells was not observed when rabbit hepatocytes were used as target cells, but mononuclear cells of alcohol-fed baboons were cytotoxic against hepatocytes of both control animals and hepatocytes from alcohol-fed baboons, including the animals' own hepatocytes. Increased vulnerability of hepatocytes of alcohol-fed baboons was also demonstrated since mononuclear cells of both controls and alcohol-fed animals were more cytotoxic against hepatocytes of alcohol-fed baboons than against those of controls. Thus, autologous and heterologous hepatocytes are more sensitive in the baboon than rabbit hepatocytes in demonstrating cytotoxicity already at the stage of fatty liver. Two factors are contributory: mononuclear cells cytotoxicity and vulnerability of hepatocytes.

Antibodies against human liver-specific protein (LSP) in acute and chronic viral hepatitis types A, B and non-A, non-B

Sera from 42 patients with acute viral hepatitis (AVH), 97 patients with chronic active liver disease (CALD) and 89 controls were tested by radioimmunoprecipitation for the presence of antibodies against human liver-specific protein (LSP). Anti-LSP were found in all but one patient with AVH type A (93%) and in a smaller percentage of AVH type B (55%). In non-A, non-B cases, anti-LSP were found in low percentages: 27% in acute cases, 10% in chronic cases. Furthermore, in CALD, a significant difference was found between HBsAg-positive CAH and 'autoimmune' CAH, a significant difference was found between HBsAg-positive CAH and 'autoimmune' CAH, both in anti-LSP prevalence (21%, 67%; P less than 0.005) and in anti-LSP titre (1:154 +/- 170, 1:316 +/- 186; P less than 0.005). In HBsAg-negative/anti-HBc-positive CAH, three of 15 patients were anti-LSP positive. Anti-LSP were found only in three of 57 patients with various non-hepatic diseases with autoimmune features. None of the 12 healthy HBsAg carriers was positive. Hence there is evidence for a considerable heterogeneity in anti-LSP response in acute and in chronic inflammatory HBsAg-negative liver diseases. These data suggest that anti-LSP antibodies do not play a prominent role in the process of transition to chronicity of acute viral hepatitis particularly in non-A, non-B cases, whereas these antibodies may be important in the mechanism of ongoing liver cell injury in patients with 'autoimmune' CAH, and can represent a useful diagnostic marker of this type of hepatitis.

Spontaneous cell-mediated (SCMC) and antibody-dependent cellular cytotoxicity (ADCC) in patients with acute and chronic active hepatitis

spontaneous (SCMC) and antibody-dependent (ADCC) cellular cytotoxicity was studied in patients with aucte viral hepatitis B and chronic active hepatitis (CAH) B and non-A, non-B. Chang cells displaying the liver-specific protein LSP on the plasma membrane were used as target cells. SCMC and ADCC in acute hepatitis B were not different from normal controls. SCMC and ADCC in chronic active hepatitis B as well as in non-A, non-B were significantly elevated in comparison to normal controls. In additional experiments, the influence of patients sera on SCMC and ADCC was studied. Autologous serum from CAH patients significantly reduced cytotoxicity in SCMC and ADCC assays. This inhibitory capacity of patients sera was attributable to immune complexes, as ultracentrifugation studies and determination of immune complexes of fractionated sera demonstrated.

The immunopathogenesis of chronic HBV induced liver disease

In conclusion, until the cellular biology of hepatitis B virus infection is understood and until the technology for the development of suitable virus infected autologous target cells is available, it will not be possible to definitively establish the mechanism involved in the pathogenesis of hepatitis B virus induced hepatocellular injury. Clearly, considerable effort must now be focused on the basic biology of virus infection, replication, and effects on hepatocellular metabolism before it will be possible to perform the definitive experiments to elucidate the role played by the immune system in the pathogenesis of this disease.

Mechanisms of host defense in well nourished patients with chronic alcoholism

Tests of immune function were performed on five recently abstinent, well nourished,and disease-free patients with chronic alcoholism. No significant defects in adherence, metabolic, or bactericidal activity of polymorphonuclear leukocytes were found when compared to sex-matched controls. Antibody-dependent and natural killer cellular cytotoxicity of monocyte-macrophages and lymphocytes also were normal. These data support the concept that immunity might be intact in the group of patients with chronic alcoholism who are recently sober, well nourished, and free of underlying disease.

Lymphocyte transformation test with rabbit liver specific lipoprotein (RLSP) in chronic active hepatitis

Cellular sensitization to rabbit liver specific lipoprotein (RLSP) has been investigated using a lymphocyte transformation test in patients with chronic active hepatitis (CAH). A stimulation index greater than 2 was recorded in twenty out of twenty-five cases (eight of ten HBsAg positive and twelve of fiteen HBsAg negative) while values were lower than 2 in all the normal subjects. These results confirm the finding of sensitization to LSP in chronic active hepatitis irrespective of HBsAg status and show that rabbit LSP can be used as an alternative to the human antigen in the lymphocyte transformation test, and is further evidence that this liver membrane lipoprotein has antigenic determinants which have species-cross-reactivity.