A comparison of the prevalence of autoantibodies in individuals with chronic hepatitis C and those with autoimmune hepatitis: the role of interferon in the development of autoimmune diseases

BACKGROUND AND OBJECTIVES

Viral hepatitis due to hepatitis C virus results in chronic liver disease in more than 70% of individuals infected with the virus. Hepatitis C virus is also thought to be the cause of autoimmune chronic hepatitis, type II. The only treatment for chronic hepatitis C is interferon (IFN). IFN is both an antiviral agent and an up regulator of the cellular immune system. The latter effect is non-specific. Thus, IFN diffusely activates the cellular immune system and can initiate new autoimmune diseases in patients treated with it. To determine the prevalence of autoantibodies in patients with chronic hepatitis C and in patients with autoimmune hepatitis and to determine the incidence of new onset autoimmune disease in IFN-treated subjects with chronic hepatitis C, the records of 323 unselected patients with chronic hepatitis were reviewed.

MATERIAL AND METHODS

A total of 203 patients with a mean age of 45.7 +/- 0.8, ranging 18-81 with either HCV disease or autoimmune hepatitis, were identified and studied. One hundred sixty-two patients with chronic hepatitis C defined by elevations of serum alanine aminotransferase (ALT) for at least 6 months, the presence of detectable anti-HCV (HCV; second generation enzyme immunoassay [EIA2], a positive recombinant immunoblot assay [RIBA], the presence of HCV-RNA by PCR in serum and an abnormal biopsy consistent with chronic hepatitis C) were identified. Each was also negative for HbsAg, HbeAg and anti-Delta. Forty-one patients with a putative autoimmune chronic hepatitis (AIH) diagnosed on the basis of serologic positivity for classical autoantibodies (ANA and anti-smooth muscle antibodies), tissue typing (B8, Dr3 positive), characteristic liver biopsy findings and the absence of anti-HCV and HCV-RNA in serum were identified. The records of both of these groups of patients were reviewed for the following antibodies: anti-nuclear antibodies (ANA), antimitochondrial antibodies (AMA), anti-liver-kidney microsomal antibody (LKM), anti-smooth muscle antibodies (SMA), anti-microsomal antibodies (MSA).

RESULTS

The rate of ANA positivity was 63% in both groups; the rate of SMA positivity was 65% in patients with HCV infection (group I) and 63% in patients with AIH (group II). AMA was positive in 4% of the subjects in group I and 50% of the subjects in group II; anti-LKM antibodies were absent in all 91 HCV cases and were present in 4% of the cases in group II; MSA positivity was present in 17% of group I and 10% of group II. Eighty-one of the one hundred sixty-two patients (50%) with chronic hepatitis C received IFN treatment at a dose of 5 MU SQ daily for 6 months. Thirty-two of these eighty-one patients (42 females and 39 males with a mean age of 45.0 +/- 1.3, ranging from 18 to 81 yr.) had at least two autoantibodies detectable prior to the IFN therapy (subgroup 1) and 49 had one or no identifiable autoantibodies (subgroup 2) present prior to IFN therapy. No significant differences in the interferon response rate defined by HCV-RNA negativity and normalization of serum ALT levels at the end of therapy was noted between those with autoantibodies and those without autoantibodies. Fifteen of the interferon-treated patients developed a clinical manifestation of a new onset autoimmune disease during the course of their interferon treatment. Six of the fifteen patients belonged to subgroup 1 (n = 32) and the remaining 9 patients to subgroup 2 (n = 49) (p > 0.05). None were managed by discontinuing the interferon. Most required some form of specific treatment.(ABSTRACT TRUNCATED)

Novel peptide-binding proteins and peptide transport in normal and TAP-deficient microsomes

Most major histocompatibility complex (MHC) class I-binding peptides are translocated by TAP heterodimers, but some enter the ER lumen by alternative pathways. To further define mechanisms of peptide handling, we developed a system for the analysis of peptide-binding components in the ER membrane and lumen using iodinated cross-linkable peptide derivatives. Here we demonstrate that at least three proteins bind peptides in the ER lumen. Peptide cross-linking to these lumenal proteins can be used as an alternative method to monitor peptide transport. TAP and one other protein bind peptides on the cytoplasmic face of the ER. The presence of multiple peptide-binding proteins necessitates caution in interpreting traditional peptide-binding and transport assays. Finally, we demonstrate sequence-specific peptide transport in TAP-deficient cells transfected with only rat TAP1.

Identification of cytochromes P450 involved in the human liver microsomal metabolism of the thromboxane A2 inhibitor seratrodast (ABT-001)

Seratrodast (ABT-001, AA-2414) undergoes cytochrome P450 (CYP)-dependent metabolism to a major (5-methylhydroxy seratrodast; 5-HOS) and a minor 4'-hydroxy seratrodast metabolite in human liver microsomes. The mean apparent K(m) and Vmax for the formation of 5-HOS were 15.5 microM and 589.0 pmol 5-HOS formed/mg protein/min, respectively. Chemical inhibition using isoform-selective CYP inhibitors, correlation of 5-HOS formation with several isoform-specific CYP activities in a panel of liver microsomes, metabolism by microsomes derived from CYP cDNA-expressed B-lymphoblastoid cells, and immunoinhibition by isoform-specific anti-CYP antibodies indicated that 5-HOS formation is catalyzed by CYP3A and CYP2C9/10, with a minor contribution from CYP2C8 and CYP2C19. At clinically relevant concentrations, seratrodast was found to inhibit tolbutamide methylhydroxylation (IC50 = 60 microM), (S)-mephenytoin 4'-hydroxylation (IC50 = 50 microM), and coumarin 7-hydroxylation (IC60 = 95 microM), indicating the potential for significant clinical interactions. The inducers of CYP3A and/or CYP2C9 (e.g. rifampicin and phenytoin) are likely to alter the disposition of seratrodast.

Antigenic targets in tienilic acid hepatitis. Both cytochrome P450 2C11 and 2C11-tienilic acid adducts are transported to the plasma membrane of rat hepatocytes and recognized by human sera

Patients with tienilic acid hepatitis exhibit autoantibodies that recognize unalkylated cytochrome P450 2C9 in humans but recognize 2C11 in rats. Our aim was to determine whether the immune reaction is also directed against neoantigens. Rats were treated with tienilic acid and hepatocytes were isolated. Immunoprecipitation, immunoblotting, and flow cytometry experiments were performed with an anti-tienilic acid or an anti-cytochrome P450 2C11 antibody. Cytochrome P450 2C11 was the main microsomal or plasma membrane protein that was alkylated by tienilic acid. Inhibitors of vesicular transport decreased flow cytometric recognition of both unalkylated and tienilic acid-alkylated cytochrome P450 2C11 on the plasma membrane of cultured hepatocytes. Tienilic acid hepatitis sera that were preadsorbed on microsomes from untreated rats (to remove autoantibodies), poorly recognized untreated hepatocytes in flow cytometry experiments, but better recognized tienilic acid-treated hepatocytes. This recognition was decreased by adsorption with tienilic acid or by preexposure to the anti-tienilic acid or the anti-cytochrome P450 2C11 antibody. We conclude that cytochrome P450 2C11 is alkylated by tienilic acid and follows a vesicular route to the plasma membrane. Tienilic acid hepatitis sera contain antibodies against this tienilic acid adduct, in addition to the previously described anticytochrome P450 autoantibodies.

Cytochrome P4502E1 hydroxyethyl radical adducts as the major antigen in autoantibody formation among alcoholics

BACKGROUND & AIMS

We have previously reported that alcoholics have increased titers of immunoglobulins reacting with protein adducts of hydroxyethyl free radicals. Because hydroxyethyl radicals are produced during ethanol metabolism by liver microsomes, the aim of this study was to determine whether such antibodies recognize microsomal proteins complexed with hydroxyethyl radicals.

METHODS

Liver microsomal proteins reacting with the anti-hydroxyethyl radical antibodies were characterized by an enzyme-linked immunosorbent assay and Western blotting.

RESULTS

Alcoholic cirrhotics, but not patients with nonalcoholic cirrhosis or healthy subjects, had increased serum levels of immunoglobulin G and A directed against antigens produced in microsomes incubated with reduced nicotinamide adenine dinucleotide phosphate (NADPH) and ethanol. Such immunoreactivity was completely blocked when microsomes were incubated with ethanol in the presence of the spin-trapping agent 4-pyridyl-1-oxide-t-butyl nitrone or by preincubating the sera with hydroxyethyl radical-bound human albumin. Immunoblotting of proteins from human liver microsomes incubated with NADPH and ethanol showed that 86% of the sera from alcoholic cirrhotics reacted with a 52-kilodalton protein, whereas variable reactivity was observed with proteins of 78, 60, and 40 kilodaltons, respectively, The 52-kilodalton protein was identified by immunoblotting and immunoprecipitation as ethanol-inducible cytochrome P4502E1.

CONCLUSIONS

Antibodies from alcoholic cirrhotics specifically recognized hydroxyethyl radical-cytochrome P4502E1 adducts, suggesting the possible implication of these antigens in the development of autoimmune reactions in alcoholic liver disease.

Immunochemical detection of covalently modified protein adducts in livers of rats treated with methyleugenol

Methyleugenol is an allylbenzene food flavoring which has been shown to form DNA and protein adducts, and to cause hepatotoxicity and carcinogenicity in rodents. In order to investigate the nature of the protein adducts, specific antisera were raised by immunizing rabbits with conjugates prepared by coupling 1'-acetoxymethyleugenol, or its acidic congener 3,4-dimethoxycinnamic acid, to rabbit serum albumin (RSA). These polyclonal antisera were shown by enzyme linked immunosorbent assay (ELISA) to contain antibodies which recognized the 3,4-dimethoxyphenyl ring portion of methyleugenol. Analysis of livers from rats given methyleugenol i.p. for 5 days, at doses between 10 and 300 mg/kg/day, revealed dose-dependent formation of novel protein adducts which were recognized by the antisera. The adducts were detected by ELISA and by immunoblotting and were concentrated in the microsomal fraction, and were shown in inhibition studies to be derived from methyleugenol. A 44 kDa adduct was the only protein adduct detected in livers of rats given low loses of methyleugenol (10 or 30 mg/kg/day) and was the major adduct detected in rats given high doses of the compound (100 and 300 mg/kg/day). This adduct was solubilized when microsomal fractions were extracted using 0.1 M sodium carbonate, implying that it is a peripheral membrane protein. A pattern of protein adducts which mirrored the in vivo situation was generated when rat hepatocytes were incubated with 1'-hydroxymethyleugenol in vitro, but could not be reproduced in experiments undertaken using liver microsomes or postmitochondrial supernatants. These findings imply that generation of protein adducts in livers of rats given methyleugenol in vivo proceeds via the 1'-hydroxy metabolite and requires crucial cofactors, and/or structural features, which are present in intact hepatocytes but not in broken cell preparations and which remain to be defined.

Thalidomide prolonged graft survival in a rat cardiac transplant model but had no inhibitory effect on lymphocyte function in vitro

The effects of thalidomide on in vitro interleukin 2 (IL-2) production and thymidine uptake by human peripheral blood lymphocytes or rat splenocytes were investigated. Phytohaemagglutinin-stimulated human lymphocytes were incubated in the presence of thalidomide added at culture initiation. No immunosuppressive effect of thalidomide was observed in these experiments. Primary human mixed lymphocyte cultures treated with thalidomide for 6 days were also unaffected. A microsomal rabbit liver homogenate was prepared for metabolizing thalidomide. Stimulated lymphocytes secreted significantly more IL-2 in the presence of microsomal-treated thalidomide than did controls. The effect of thalidomide was then studied either as single therapy or in combination with cyclosporin A (CyA) in a rat allograft cardiac transplantation model. In addition, T cell subsets were analysed by flow cytometry in untransplanted rats treated with thalidomide. Treatment was given as induction therapy from the day of transplantation until day 9. Graft survival in rats treated with thalidomide was significantly prolonged compared to the untreated group. No difference in graft survival was detected between rats treated with thalidomide or CyA only. Graft survival was found to be slightly prolonged in rats given thalidomide and CyA in combination compared to rats treated with CyA alone. In untransplanted rats given thalidomide a decrease of CD4 positive T cells was detected on days 3 and 5. The T helper/cytotoxic-suppressor cell ratio was significantly diminished but, after 1 week of treatment, values for T cell subsets had almost returned to baseline levels. No inhibitory effect was obtained when phytohaemagglutinin-stimulated rat splenocytes were cultured with metabolized thalidomide. In summary, the ability of thalidomide to improve allograft survival in a solid organ transplant model was verified. The occurrence of thalidomide-induced changes in T cell subset ratios was demonstrated. In in vitro studies, however, there was no decrease but an increase in IL-2 production, and no change in thymidine uptake. The mechanism responsible for the immunosuppressive effect of thalidomide remains to be elucidated.

[Chronic hepatitis C virus infection associated with anti-LKM 1]

A case of chronic hepatitis in a 20-year-old patient in whom hepatitis C virus infection markers and type 1 liver and kidney antimicrosome antibodies (anti-LKM 1) were detected, thereby allowing diagnosis of autoimmune type 2b hepatitis, is reported. The different types of autoimmune hepatitis (AIH) and the type 2a and 2b AIH are discussed as are the rejection of this terminology by some authors followed by their proposals and the therapeutic strategy to be used in these patients.

Immunochemical detection of protein adducts in mice treated with trichloroethylene

Trichloroethylene has been shown to produce tumors in rodents and is a suspect human carcinogen. In addition, a number of case reports raise the possibility that trichloroethylene can induce an autoimmune disorder known as systemic sclerosis. To investigate whether covalent binding of reactive trichloroethylene metabolites may be involved in the mechanisms underlying these toxic responses, we have developed a polyclonal antibody that can recognize trichloroethylene--protein adducts in tissues. The antibody was prepared by immunizing a rabbit with dichloroacetic anhydride-modified keyhole limpet hemocyanin. Enzyme-linked immunosorbent assay data indicated that the serum antibody recognized dichloroacetic anhydride-modified rabbit serum albumin, but not unmodified protein. In addition, N epsilon-dichloroacetyl-L-lysine was the most potent inhibitor of antibody binding to dichloroacetic anhydride-modified rabbit serum albumin, indicating that the antibody recognizes primarily dichloroacetylated lysine residues. Immunoblots revealed the presence of two major trichloroethylene adducts at 50 and 100 kDa in liver microsomal fractions from male B6C3/F1 mice treated with trichloroethylene. The formation of trichloroethylene adducts was both dose and time dependent. Furthermore, the 50-kDa adduct was found to comigrate on a polyacrylamide gel with cytochrome P450 2E1. These data show that reactive metabolites of trichloroethylene are formed in vivo and bind covalently to discrete proteins in mouse liver. The data also suggest that one of the protein targets is cytochrome P450 2E1. Further studies will be necessary to elucidate the relationship between covalent binding of trichloroethylene and trichloroethylene toxicity.

Expression and inducibility of antigens in severe combined immunodeficient mice recognized by human anti-P450 antibodies

Engrafting components of human immune systems in severe combined immunodeficient (SCID) mice has been utilized to investigate the pathogenesis of several human autoimmune diseases and may provide a model for studying idiosyncratic drug toxicity. The purpose of this investigation was to examine in SCID mice the tissue distribution and inducibility of antigens recognized by anti-cytochrome P450 (CYP) antibodies in sera from patients with hypersensitivity reactions to the aromatic anticonvulsants phenytoin, phenobarbital, and carbamazepine. Microsomal proteins were prepared from liver, skin, kidney, intestine, and lung of SCID mice pretreated with vehicle (50% propylene glycol/DMSO), phenytoin, carbamazepine, phenobarbital, or dexamethasone. Proteins immunoreactive with anti-CYP2C and anti-CYP3A antisera were detected in all organs examined. Antibodies in patient sera recognized a 53-kDa hepatic microsomal protein that was expressed to a limited extent in vehicle-pretreated microsomes, but which was induced by dexamethasone, phenytoin, and phenobarbital, but not carbamazepine. This antigen was very similar to a 52.5-kDa protein immunoreactive with anti-CYP3A polyclonal antibody. The expression and inducibility of the 53-kDa antigen correlated significantly with testosterone 6 beta-, 2 beta-, and 15 beta-hydroxylation and erythromycin N-demethylase activity, all markers of CYP3A activity, and is tentatively identified as CYP3A11. No immunoreactivity was observed in murine extrahepatic organs including skin, kidney, intestine, and lung. Therefore, further development of the SCID mouse model may require xenotransplantation of human target organs like skin together with transfer of patient immune systems to reproduce the serological and pathological features of human anticonvulsant hypersensitivity reactions.

Significance of extractable nuclear antigens in childhood autoimmune liver disease

Antinuclear antibody (ANA) is found in connective tissue disorders and in autoimmune liver disease. While ANA-positive connective tissue disorders are subdivided according to possession of specific antibodies to extractable nuclear antigens (ENA) (anti-ribonucleoprotein (anti-RNP), anti-Smith (anti-Sm), anti-Ro, anti-La), little is known about the presence and significance of ENA in autoimmune liver disease. To investigate this, we have tested 35 children with autoimmune hepatitis (AIH) (19 ANA and/or smooth muscle antibody-positive (ANA/SMA+ve); 16 liver kidney microsomal 1-positive (LKM-1 + ve)) and 14 with ANA/SMA+ve autoimmune sclerosing cholangitis (ASC), using both double dimension immunodiffusion and ELISAs. Eighty children with non-autoimmune liver disease (20 alpha 1-antitrypsin deficiency, 20 Wilson's disease, 20 Alagille's syndrome and 20 chronic hepatitis B virus infection) and 20 healthy controls were also tested. ENA were detected in seven (20%) patients with AIH: two ANA-positive, one SMA-positive and four LKM-1-positive. Three were positive for anti-Sm, two for anti-La, one for anti-Sm/anti-La and one for anti-Sm/anti-La/anti-Ro. ENA-positive had more severe liver disease than ENA-negative patients (P < 0.03). ENA were not detected in ASC, non-autoimmune liver diseases and controls. Our results indicate that ENA reactivity, including anti-Sm and anti-La, characteristic of systemic lupus erythematosus and Sjögren's syndrome, respectively, are present in some patients with AIH even in the absence of ANA, and may characterize a particularly severe form of the disease.

Characteristics of ATP-dependent peptide transport in isolated microsomes

This report examines the transport properties and specificity of ATP-dependent peptide transport by the murine transporter for Ag presentation (TAP) complex in isolated microsome preparations from H-2d haplotype mice. The murine TAP complex has a Km of 661 nM and a maximum velocity of 2.9 fmol/min.micrograms microsome protein for a modified peptide corresponding to a defined MHC class I binding epitope from influenza nucleoprotein recognized by CD8+ CTL in association with the Kd molecule. This high Km value for peptide transport suggests that the rate and efficiency of peptide transport of the TAP complex are influenced by the concentration of processed peptides derived from self and foreign proteins in the cell cytoplasm. Furthermore, these findings imply that competition among peptides for TAP-dependent transport is unlikely to be an important factor in determining the immunodominance of certain peptide epitopes within a foreign protein recognized by CD8+ T lymphocytes. We also examined the specificity of TAP transport for peptides containing bona fide murine MHC class I binding epitopes and provide evidence that certain flanking residues can affect the efficiency of peptide epitope transport by the TAP complex.

Importance of T-cell-dependent inflammatory reactions in the decline of microsomal cytochrome P450 concentration in the livers of rats infected with Fasciola hepatica

The concentration of cytochrome P450, measured spectrophotometrically in microsomal preparations from the livers of rats infected with 30 metacercariae of Fasciola hepatica, declined by approximately 50% at 3 weeks post-infection. Treatment of infected rats with the anti-inflammatory agent dexamethasone (2 mg/kg at 48 h intervals for 8 days prior to assay) abolished the decline in P450 content. Assay of P450 in infected congenitally athymic (nude) rats showed normal levels. These results demonstrate that the T-cell-dependent inflammatory response in the liver of the host is a necessary factor in the development of the decline in hepatic P450, which is known to compromise the metabolism of certain drugs in infected hosts.

Liver cytosolic 1 antigen-antibody system in type 2 autoimmune hepatitis and hepatitis C virus infection

Within the multiform liver/kidney microsomal (LKM) family, a subgroup of sera that reacts with a liver cytosolic (LC) protein has been isolated and the new antigen-antibody system is called LC1. Unlike LKM antibody type 1 (anti-LKM1), anti-LC1 is said to be unrelated to hepatitis C virus (HCV) infection and has therefore been proposed as a marker of 'true' autoimmune hepatitis type 2. Altogether 100 LKM1 positive sera were tested by immunodiffusion (ID). Twenty five gave a precipitation line with human liver cytosol; 17 of the 25 also reacted with rat liver cytosol. Thirteen of the 25 sera were anti-HCV positive by second generation ELISA: anti-HCV positive patients were significantly older (p < 0.001) and tended to have less active disease. No difference in anti-LC1 titre or ID immunoreactivity was found between anti-LC1/anti-HCV positive and anti-LC1/anti-HCV negative cases. In Western blotting experiments, 14 of 24 ID positive sera recognised a 58 kD protein of the human cytosolic fraction and 11 gave a similar reactivity when tested with human microsomes, suggesting the presence of the LC1 target antigen also in the microsomal preparation. Western blotting reactivity was similar for both anti-HCV positive and negative sera. These data confirm the existence of the LC1 antigen-antibody system that partially overlaps with LKM1, and that it is an additional marker of juvenile autoimmune hepatitis type 2. It does not, however, discriminate between patients with and without HCV infection.

[Heterogeneity of antimicrosomal autoantibodies in chronic hepatitis C virus infection and delta hepatitis]

Microsomal antigen autoantibodies are typical of type 2 autoimmune hepatitis, and a strong association with chronic hepatitis C virus (HCV) infection has been reported in certain geographical areas. These autoantibodies have been denominated LKM-1 to differentiate them from those associated with thienylic acid-induced hepatitis (LKM-2) and from those seen in patients with chronic delta hepatitis (LKM-3). To investigate the antigenic specificity of autoantibodies associated with chronic hepatitis C and delta, we analyzed 52 LKM-1 positive serum samples from patients with chronic hepatitis C and 17 LKM-3 positive serum samples from patients with chronic delta hepatitis by indirect immunofluorescence and Western blotting (immunoblotting). Reactivity of subjects with chronic hepatitis C was heterogeneous: only 5 out of 52 LKM-1 positive patients, tested by Western blot, recognized a single protein of 50 kD, previously identified by Manns et al. with an immunogenic epitope of cytochrome P450IID6. Thirteen of the 52 patients also reacted with a 70 kD microsomal protein, and 12 out of 52 reacted only with a 59 kD protein. Twenty-two sera, notwithstanding the high titer in immunofluorescence, did not evidence any reactivity when tested by Western blot. The same sera tested positive in LKM-1 ELISA when solubilized human microsomal proteins were used. Fourteen out of 17 LKM-3 positive sera from patients with chronic hepatitis delta recognized a 55 kD microsomal protein in Western blot; three sera, HCV and HIV positive, did not react with any protein by Western blot. None of these sera was positive in ELISA LKM-1.(ABSTRACT TRUNCATED AT 250 WORDS)

[Anti-GOR antibodies in type II mixed cryoglobulinemia associated with hepatitis C virus infection]

The frequent association of chronic hepatitic C virus (HCV) infection and type II mixed cryoglobulinemia is considered to be one of the possible signs of interaction between the virus and the immune system. This could also be the case for the appearance of anti-GOR antibodies in serum, as they react with both viral and host antigens. We studied a group of patients with chronic hepatitis C infection and a group with type II mixed cryoglobulinemia associated with HCV infection to ascertain if anti-GOR or other non-organ specific autoantibodies were present in the serum. We found no significant difference between the two groups in presence, prevalence or titer of anti-GOR or other autoantibodies. Moreover, the expression of anti-GOR does not seem to influence the severity of liver damage. Our data support the hypothesis that anti-GOR antibodies are a simple expression of molecular mimicry between viral and human epitopes.

High prevalence of serological markers of autoimmunity in patients with chronic hepatitis C

The advent of specific antiviral therapy for chronic hepatitis C has increased the importance of establishing the correct etiology of chronic hepatitis in patients, especially because interferon alfa (IFN-alpha) has been reported to exacerbate autoimmune hepatitis (AIH), whereas corticosteroids increase viral replication in chronic hepatitis C. In our medical center, we have treated many patients with apparent chronic hepatitis C and serological or clinical evidence of autoimmunity. Our aim was to estimate the prevalence of this association and to learn whether demographic or clinical features distinguished between patients with or without autoimmune markers. We performed a retrospective review of the records of 244 unselected patients seen at the Clinics and Hospital of the University of Massachusetts between May 1991 and November 1993, who had elevated serum aminotransferases. One hundred seventeen patients had chronic hepatitis C defined by elevations of serum alanine transaminase (ALT) for at least 6 months, positive serum antibodies to hepatitis C virus (HCV; second-generation enzyme immunoassay [EIA2] or recombinant immunoblot assay [RIBA]), and absence of hepatitis B surface antigen in the serum. Records were reviewed for results of autoimmune markers in sera, including anti-nuclear antibodies (ANAs), anti-smooth muscle antibodies (SMAs), rheumatoid factor (RF), antimitochondrial antibodies (AMAs), anti-liver and kidney microsomal (LKM) antibodies, and cryoglobulins. We found a high prevalence of positivity, particularly for anti-SMAs (66%) and RF (76%) in both men and women. Forty of 41 patients tested negative for anti-LKM antibodies.(ABSTRACT TRUNCATED AT 250 WORDS)

Occurrence of autoimmune antibodies to liver microsomal proteins associated with lethal hepatitis in LEC rats: effects of TJN-101 ((+)-(6S,7S,R-biar)- 5,6,7,8-tetrahydro-1,2,3,12-tetramethoxy-6,7-dimethyl-10,11- methylenedioxy-6-dibenzo[a,c]cyclooctenol) on the development of hepatitis and the autoantibodies

Long Evans Cinnamon (LEC) rats, that spontaneously develop hepatitis, were found to possess autoantibodies to liver microsomal proteins (anti-LM) before the development of hepatitis. Anti-LM antibody was assumed to appear in association with the lethal hepatitis in the LEC rats. Thus, the purpose of this study was to investigate the effects of an anti-hepatitis drug on the development of hepatitis and the occurrence of the antibody in LEC rats. Mortality, blood biochemical parameters and the titer of serum anti-LM antibody were measured. In control LEC rats, 4 of 8 rats died before 20 weeks of age. In rats treated with TJN-101 ((+)-(6S,7S,R-biar)-5,6,7,8-tetrahydro-1,2,3,12-tetramethoxy -6,7-dimethyl-10,11 - methylenedioxy-6-dibenzo[a,c]cyclooctenol), 4 of 7 rats died of hepatitis, but the time of death was delayed by 7-10 weeks compared to the control rats. The titer of the anti-LM antibody increased 3-7 weeks before death in the non-survivors in control and TJN-101-treated rats, supporting the idea that anti-LM antibody occurs in association with acute lethal hepatitis.

CD8+ dermal T cells from a sulphamethoxazole-induced bullous exanthem proliferate in response to drug-modified liver microsomes

There is evidence that T lymphocytes play a critical role in the pathogenesis of drug-induced bullous exanthems. Sulphonamides are known to be among the most frequent aetiological agents in these severe drug-induced cutaneous hypersensitivity reactions. Several studies indicate that cytochrome P450-dependent metabolites of sulphonamides act as the nominal allergens. A 70-year-old woman with a severe blistering exanthem caused by cotrimoxazole (sulphamethoxazole and trimethoprim) was studied. We employed an in vitro approach to determine whether cytochrome P450-dependent enzymes activated drug-specific T lymphocytes from this patient. Immunohistochemical analysis of involved skin revealed a majority of epidermal CD8+ T lymphocytes, whereas the dermal infiltrate was composed of both CD4+ and CD8+ T cells. Dermal T lymphocytes isolated from lesional skin proliferated in response to sulphamethoxazole, but not to trimethoprim, in the presence of autologous mononuclear cells used as antigen-presenting cells. The antigen-specific response of sulphamethoxazole-specific T cells was significantly augmented in the presence of murine liver microsomes with P450-dependent catalytic activities. Our observations suggest that some cutaneous hypersensitivity reactions to sulphamethoxazole are due to drug-specific T lymphocytes. Cytochrome P450-dependent enzymes may play a critical role in the formation of the nominal antigen, which is recognized by antigen-specific T cells.

A rapid, single-step purification method for immunogenic members of the hsp 70 family: validation and application

Gelatin affinity chromatography has been developed as a simple one-step procedure for purification of members of the hsp 70 kDa family from MDBK cells (a bovine epithelioid cell line), rat liver microsomes and three different protozoan parasites. The ability of the isolated proteins to bind to denatured proteins like gelatin together with their apparent molecular masses, constitutive and inducible expression and their release from gelatin-agarose beads by ATP suggested that these proteins are molecular chaperones. The identity of a gelatin bound, ATP released, 78 kDa protein isolated from rat liver was confirmed by comparison of its NH2-terminal sequence with that of grp 78/BiP from rat. A 68 kDa protein isolated from Trypanosoma brucei brucei (T.b. brucei) and proteins of 68 and 69 kDa from Leishmania donovani (L. donovani) using gelatin affinity chromatography reacted in Western blot analysis with a monoclonal antibody, 7.10, specific for members of the 70 kDa heat shock protein family derived from a wide variety of species. A different monoclonal antibody, SPA-820, which also recognises members of the hsp 70 kDa family, bound to proteins isolated from Theileria parva Muguga transformed lymphoblastoid cell lines (TpM). The gelatin bound ATP released proteins of 72 kDa from T.b. brucei and of 65, 69 and 72 kDa from TpM were detected by recovery sera of the cattle infected with T.b. brucei and T. parva, respectively.

Role of metabolism in monocrotaline-induced immunotoxicity in C57BL/6 mice

Monocrotaline (MCT) is a pyrrolizidine alkaloid which has been shown to induce immunotoxicity in mice. We hypothesized that metabolic activation of MCT by mixed-function oxygenases (MFO) to dehydromonocrotaline (MCTP) is a prerequisite for its immunotoxicity, as has been shown for other toxic effects of MCT. To test this hypothesis, we compared the in vitro immunotoxic potency of MCT and MCTP to suppress the in vitro antibody response to SRBC and the blastogenic response to B and T cell mitogens. In addition, the effects of in vivo modulation of MFO activities on the immunotoxicity of MCT was examined using phenobarbital (PB) to increase and chloramphenicol (CP) to decrease MCTP production. Results showed that in vitro exposure of splenic lymphocytes to MCT or MCTP produced significant suppression of the antibody and blastogenic responses. MCTP was 200-400-fold more potent than MCT. No metabolism of MCT by splenic cells was detectable, suggesting that unmetabolized MCT is capable of inducing immunotoxicity. In vivo studies showed that, while treatment of mice with PB or CP produced significantly increased and decreased MCTP production by liver microsomes, neither PB or CP treatment significantly altered the immunotoxic potency of MCT. Thus, while the MCTP metabolite is directly immunotoxic in vitro and much more potent than MCT, a role for the MCTP metabolite in MCT immunotoxicity in vivo could not be demonstrated.