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Biomedical subjects

A W Lohse

Publications and source records attributed to A W Lohse.

At least 19 recordsLinked to original sources
PubMed1997

Humoral mechanisms in T cell vaccination: induction and functional characterization of anti-lymphocytic autoantibodies.

T cell vaccination, the application of syngeneic attenuated T cells, has been shown to prevent effectively and treat experimental autoimmune diseases, but its mechanisms of action are poorly understood. Here we present data on the induction of a humoral anti-T cell response by T cell vaccination, capable of strongly inhibiting T cell proliferation and of ameliorating experimental autoimmune disease. T cell vaccination in the Lewis rat induced autoantibodies reactive with several syngeneic T cell proteins. These autoantibodies were not detectable in normal Lewis sera as assessed by immunoblotting and flow cytometry with intact syngeneic T cells. The autoantibody reactivity was not restricted to one idiotype, was detected as early as 1 week after vaccination and was dominated by IgG, suggesting the boosting of a naturally preformed humoral network by T cell vaccination. Recovery from passively or actively induced experimental autoimmune encephalomyelitis (EAE) in the Lewis rat, too, could be shown to be associated with the development of anti-T cell autoantibodies. In vitro, both the post-EAE and the post-vaccination sera had a strong suppressive effect on the proliferation of syngeneic T cell clones. This inhibition was shown to be mediated by antibodies and to be partly complement-dependent. In vivo, both kinds of sera were able to ameliorate EAE. This protective effect of the post-vaccination sera was not idiotype-specific, since sera obtained after T cell vaccination with an unrelated T cell clone were similarly effective in suppressing EAE. These results suggest that anti-lymphocytic antibodies might play an immunoregulatory role that can be positively manipulated by T cell vaccination.

Animals↗
PubMed1997

Bile duct epithelia as target cells in primary biliary cirrhosis and primary sclerosing cholangitis.

Primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC) are chronic autoimmune-mediated diseases of the biliary tree, resulting in a loss of bile ducts. There are morphological features that clearly distinguish them from each other: in PBC, there is overt destruction of the bile ducts with disruption of the basement membrane; in PSC there is abundant periductular fibrosis with shrinkage and subsequent loss of the bile ducts. In order to see if the disparate histopathology is paralleled by different immunohistology we looked at a panel of epitopes on bile duct epithelia especially to see if biliary epithelial cells may present as targets for cell mediated immune response. In PBC bile duct epithelial cells mostly expressed CD58 (lymphocyte function-associated antigen 3), CD80 (B7 BB1), and CD95 (Fas). In PSC, however, these epitopes were only expressed in a few examples to a lower degree. The respective effector T lymphocytes were positive for CD2 and CD28. Subtyping of the lymphocytes in the liver tissue further showed a predominance of CD4 positive T cells over CD8 cells up to 2-to-1 in both diseases. Determination of lymphocytes by cytokines to Th1 or Th2 subtype showed a majority of Th1 lymphocytes in PBC and PSC. We conclude that in PBC bile duct epithelial cells may display features of target cells of a T cell-mediated immune reaction with the Th1 cells predominating. In PSC other mechanisms of bile duct loss may play a role, since in this disease the majority of cells lack essential epitopes that constitute targets of cell mediated immunity.

Antigens, CD↗
PubMed1997

Cellular and humoral immunity to the 60-kD heat shock protein in inflammatory bowel disease.

BACKGROUND: Mycobacteria have been considered a possible etiological agent in Crohn's disease. Since cross-reactivity between epitopes of mycobacterial and self-heat shock protein might represent a potential disease mechanism, we determined the cellular and humoral immune responses to the mycobacterial and the human 60-kD heat shock protein, as well as various control antigens. METHODS: We studied samples from 19 patients with Crohn's disease, 12 patients with ulcerative colitis, and from 19 healthy individuals. T cell responses were studied using a standard proliferation assays to purified recombinant mycobacterial and human 60-kD heat shock protein. Antibody levels were measured by establishing an enzyme-linked immunosorbent assays to recombinant purified 60-kD heat shock protein. RESULTS: The proliferative responses to the mycobacterial and the human 60-kD heat shock protein were closely correlated, but the cellular immune response to both antigens was not significantly different between the two patient groups and healthy controls. In addition, antibody levels to heat shock protein were also not significantly different between the three groups. CONCLUSIONS: These results argue strongly against a role for mycobacterial heat shock protein in the pathogenesis of Crohn's disease. However, in view of previous data demonstrating overexpression of 60-kD heat shock protein in inflammatory Crohn's disease tissue, this considerable cellular and humoral autoreactivity suggests an important immunoregulatory role for the 60-kD heat shock protein.

Adult↗
PubMed1997

Coombs-negative severe hemolysis associated with hepatitis A.

Mild anemia can occasionally be observed during viral hepatitis, but severe hemolysis has previously only been reported in a few patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency. We report a case of massive acute hemolysis associated with an acute hepatitis A in a 39-year-old woman in the absence of G6PD-deficiency. The patient was also suffering from mild rheumatoid arthritis. All known factors responsible for hemolysis were ruled out. Although tests for autoimmune hemolytic anemia were negative the patient made a dramatic recovery after treatment with corticosteroids, suggesting an immune mediated mechanism nonetheless.

Adult↗
PubMed1997

Cyclophosphamide as alternative immunosuppressive therapy for autoimmune hepatitis--report of three cases.

Autoimmune hepatitis is a chronic inflammatory disorder of the liver with a fluctuating course, which often requires long-term immunosuppressive therapy in order to prevent fibrosis to the liver. The mainstay of immunosuppressive therapy is the use of corticosteroids, usually in conjunction with azathioprine. However, in a subgroup of patients with severe side effects or intolerance of standard therapy there is a need for alternative immunosuppressive agents. We describe the successful long-term treatment of three patients with severe autoimmune hepatitis with an immunosuppressive regimen consisting of cyclophosphamide and corticosteroids. In the reported patients we were able to induce remission with cyclophosphamide in a dose of 1-1.5 mg/kg bodyweight in combination with a tapering dose of corticosteroids beginning with 1 mg/kg bodyweight. After induction we were able to maintain histology proven remission with low doses of corticosteroids (2.5-10 mg/day) together with 50 mg of cyclophosphamide every other day. With this dose of cyclophosphamide we have neither observed relapse of autoimmune hepatitis nor severe side effects in a cumulative observation period of more than twelve years in the three patients. As a consequence of our favourable experience with cyclophosphamide in the reported cases, we propose cyclophosphamide as an alternative to azathioprine in cases of autoimmune hepatitis with severe side effects of intolerance of standard therapy.

Adult↗
PubMed1996

Detection and quantification of blood-derived CD8+ T lymphocytes secreting tumor necrosis factor alpha in response to HLA-A2.1-binding melanoma and viral peptide antigens.

We applied an enzyme-linked immunospot (ELISPOT) assay for the detection and quantification of blood-derived CD8+ T cells recognizing peptide antigens presented by HLA-A2.1. CD8+ T lymphocytes were isolated from peripheral blood and were stimulated for 40 h with peptide-loaded A2.1-positive 0.174 x CEM.T2 cells. Tumor necrosis factor alpha (TNF-alpha) secreted by single T cells in response to antigen contact was trapped on nitrocellulose membranes precoated with anti-TNF-alpha antibodies and was then immunochemically visualized as spots. With this assay, up to 25% of cloned cytolytic T lymphocytes (CTL) were detected during the test period that recognized defined melanoma antigens in association with HLA-A2.1. CD8+ lymphocytes responsive to a known immunogenic HLA-A2.1-binding peptide from reverse transcriptase of the human immunodeficiency virus (HIV) were only detectable in HIV-infected patients, but not in anti-HIV-negative donors. T cells reacting with a peptide derived from a mutated cyclin-dependent kinase 4 (CDK4-R24C) were exclusively detected among CD8+ lymphocytes isolated from blood of the patient, whose melanoma had previously been found to carry the CDK4-R24C allele. T cells responding to HLA-A2.1-associated peptides of normal melanocyte differentiation antigens tyrosinase and Melan-A/MART-1 were found at low frequencies in almost all donors tested, which might reflect a natural autoimmunity to these antigens. However, in a melanoma patient we found a few days after surgery of melanoma metastases high frequencies of T cells against Melan-A/MART-1 and tyrosinase peptides (up to 38 per 10(5) CD8+ T cells), which gradually decreased during the following months. In an HIV-infected patient with progressive disease we observed a loss of T cells reactive with the HIV reverse transcriptase peptide. These observations provide evidence that peptide-dependent TNF-alpha spot formation in vitro resulted from previous antigen exposure in vivo. Therefore, the TNF-alpha ELISPOT assay might be useful in monitoring antigen-specific T lymphocyte responses during the natural course of diseases as well as during therapeutic interventions aiming at the induction of protective T cell immunity. In addition, it might help to identify immunodominant T cell epitopes.

Amino Acid Sequence↗
PubMed1996

Role of sinusoidal endothelial cells of the liver in concanavalin A-induced hepatic injury in mice.

CD4+ T lymphocytes have been identified as being responsible for organ damage in the murine model of experimental liver injury induced by intravenous injection of concanavalin A (Con A). Liver sinusoidal endothelial cells (SEC) and Kupffer's cells (KC) are among the first cells that come into contact with lymphocytes in the liver sinusoid. We aimed to investigate the respective role of these cell populations in the initial steps of T-cell-mediated liver injury in Con A-induced hepatitis. By electron microscopy, we could show that intravenously applied Con A bound predominantly to SEC but not to KC. KC depletion by gadolinium chloride treatment of mice did not result in protection from liver injury, indicating that KCs are not primarily involved in the generation of liver injury. We could show that a CD4+ T-cell line (LNC.2) displayed selective cytotoxicity toward SEC (>50%) but not KC (12%) or fibroblasts (5%) in the presence of Con A in vitro. Microscopic observation revealed that the SEC monolayer was rapidly destroyed by LnC2 in the presence of Con A. Specificity of the Con A-induced cytotoxicity was shown by the ability of a competitive ligand, methyl-alpha-D-mannopyranoside, to reduce T-cell-mediated cytotoxicity to SEC by more than 50%. Tumor necrosis factor alpha (TNF-alpha) was produced by LnC2 in high amounts after Con A stimulation (>6 ng/mL), but antiserum to TNF-alpha did not reduce LnC2-mediated cytotoxicity toward SEC. In conclusion, we could show for the first time that liver SECs have accessory function and are selectively destroyed by CD4+ T lymphocytes in the presence of Con A. We speculate that SEC damage is an early event in T-cell-mediated liver injury recruiting T lymphocytes from the sinusoidal circulation. Loss of the SEC barrier function then exposes underlying hepatocytes to further attack by activated T lymphocytes. These results offer a model of initiating events in T-cell-mediated liver diseases, such as viral or autoimmune hepatitis, and suggest an important role for sinusoidal endothelial cells.

Animals↗
PubMed1996

Autoreactive CD4+ LKM-specific and anticlonotypic T-cell responses in LKM-1 antibody-positive autoimmune hepatitis.

Peripheral blood mononuclear cells (PBMC) of patients with autoimmune hepatitis (AIH) and controls were studied for their proliferative response to six overlapping synthetic peptides covering the 33-amino acid immunodominant region of cytochrome P450IID6, the main target antigen of LKM-1 antibody-positive type II AIH. PBMC from 8 of 8 type II AIH patients (100%), 6 of 12 LKM-1 antibody-negative type I AIH patients (50%), but only 4 of 31 patients with chronic hepatitis C (12.9%) reacted with a 23-amino acid LKM peptide and mainly with a shorter 18-amino acid LKM peptide. Follow-up showed that LKM-specific T-cell responses decreased after immunosuppression had started. Fine specificity, HLA restriction, and cytokine release of LKM-specific T cells were analyzed with 16 CD4+ peptide-specific T-cell lines and 21 CD4+ T-cell clones isolated and expanded from blood and liver tissue of six AIH patients. Activated LKM-specific T cells released interferon gamma (IFN-gamma) but no or little interleukin-4. In three AIH patients, PBMC showed specific recognition of autologous LKM-specific T cells, suggesting the presence of a regulatory T-cell network. These T cells also showed the CD4+ phenotype and secreted large amounts of IFN-gamma. Furthermore, it was assessed that the regulatory T-cell response is clonotypic. To conclude, we describe a major T-cell epitope in AIH that was recognized by Th1 helper cells isolated from blood and liver tissue. This autoreactive T-cell response correlated widely with disease activity and LKM-1 antibody status and seemed to be regulated by anticlonotypic T cells.

Adolescent↗
PubMed1996

Estimation of the frequency of self-reactive T cells in health and inflammatory diseases by limiting dilution analysis and single cell cloning.

Autoreactive T cells have recently been detected not only in autoimmune diseases but also in healthy individuals, but their frequency is thought to be low. The aim of our study was to estimate the frequency of self-reactive T cells by using limiting dilution analyses of peripheral blood lymphocytes. Assessment of self-reactivity in this study was defined as T-cell proliferation to autologous non-T cells in the absence of foreign antigens. When culture conditions were optimized by adding interleukin 2, healthy individuals showed a frequency of self-reactive T cells ranging from 1/60 to 1/600. These results were confirmed by using unseparated peripheral blood leukocytes or Epstein-Barr virus transformed B-cell blasts as stimulators. All cultures were performed exclusively in autologous serum. Single cell cloning from a healthy donor yielded 568 T-cell clones, 12 of which showed self-reactivity giving a frequency of more than 1 in 50 T cells. Eight of these 12 T-cell clones were inhibited by MHC-class II antibodies. Frequency analyses of self-reactive T cells in patients with autoimmune diseases (rheumatoid arthritis, autoimmune hepatitis or primary biliary cirrhosis), with viral hepatitis or with inflammatory bowel diseases showed similar frequencies in all patient groups and no significant differences from normal individuals. In conclusion, we have found a high frequency of self-reactive T cells in both health and disease. We postulate that self-reactive T cells constitute an important part of the physiological T-cell repertoire.

Adolescent↗
PubMed1996

Evidence for an overlap syndrome of autoimmune hepatitis and primary sclerosing cholangitis.

BACKGROUND/AIMS: Autoimmune hepatitis, primary biliary cirrhosis and primary sclerosing cholangitis are chronic liver diseases with probable autoimmune background. Overlapping features have been described for primary biliary cirrhosis and autoimmune hepatitis. In contrast, there have been only a few case reports on an overlap of autoimmune hepatitis and primary sclerosing cholangitis. METHODS: We describe three male patients with clinical and histological overlapping features of primary sclerosing cholangitis and autoimmune hepatitis. RESULTS: All initially asymptomatic patients had elevated levels of aminotransferases, alkaline phosphatase, gamma-glutamyltranspeptidase and IgG. Anti-nuclear antibodies and/or smooth muscle antibodies were positive and anti-neutrophil cytoplasmic antibodies were detected in all patients. Retrograde endoscopic cholangiography showed bile-duct strictures characteristic for primary sclerosing cholangitis. Histopathology showed necro-inflammatory activity of portal tracts with bridging necrosis in all patients at the time of first diagnosis. Aminotransferase levels and the necro-inflammatory activity responded well to immunosuppressive treatment. Predominant periductular fibrosis as a typical histopathological feature of primary sclerosing cirrhosis was seen to develop in all patients. Cholestatic serum parameters remained elevated and periductular fibrosis as endoscopic bile duct changes progressed despite immunosuppression. CONCLUSIONS: We suggest that these patients present an overlap syndrome of autoimmune hepatitis and primary sclerosing cholangitis as they fulfill the diagnostic criteria for both conditions.

Adolescent↗
PubMed1996

Antigen-presenting function and B7 expression of murine sinusoidal endothelial cells and Kupffer cells.

BACKGROUND & AIMS: Inflammatory liver disease as well as rejection of liver allografts are thought to be mediated by resident antigen-presenting cells in the liver. At the same time, in vivo antigen presentation in the liver appears to be a more tolerogenic than systemic antigen challenge. The aim of this study was to show and characterize the antigen-presenting capability of sinusoidal endothelial cells and Kupffer cells. METHODS: Purified murine sinusoidal endothelial cells and Kupffer cells were studied for their ability to serve as accessory cells and antigen-presenting cells by proliferation assays. They were also studied for their expression of interleukin 1 and the B7 costimulatory molecules by Northern blotting, polymerase chain reaction, and flow cytometry. RESULTS: Both cell types expressed interleukin 1 messenger RNA and could serve equally well as accessory and antigen-presenting cells. B7-2 messenger RNA and surface expression on sinusoidal endothelial cells and on Kupffer cells was shown. Antibodies to the B7 molecules inhibited antigen presentation. Addition of interleukin 10 as a regulatory cytokine secreted by Kupffer cells was suppressive. CONCLUSIONS: Sinusoidal endothelial cells carry functional B7-2 molecules and can serve as effective antigen-presenting cells. However, antigen presentation by sinusoidal endothelial cells may be locally down-regulated by interleukin 10.

Animals↗
PubMed1996

Post-infantile giant cell hepatitis in patients with primary sclerosing cholangitis and autoimmune hepatitis.

In post-infancy, multinucleated giant cell hepatitis is rare. Various conditions and diseases associated with post-infantile giant cell hepatitis have been described, but the pathogenesis remains unknown. In this paper we review the case reports of four patients (3 male, 1 female; aged 22 to 32 years) with primary sclerosing cholangitis and autoimmune hepatitis. The follow-up ranges from five to seven years. All patients showed cholestasis and repeated elevation of hepatic transaminases. Patients with viral infections, metabolic disorders and toxic influences were excluded. Histopathology of liver tissue in all four patients revealed giant cell formation with up to 20 nuclei in 20-70% of all hepatocytes. Post-infantile giant cell hepatitis was defined histopathologically. The clinical course of all four patients markedly improved after immunosuppressive treatment. Further improvement was observed with the addition of ursodeoxycholic acid. Follow-up liver biopsies during treatment showed reduced inflammation and a decreased number of giant cells. One patient, who initially was admitted to the hospital with liver cirrhosis died five years later due to a sepsis. The clinical course of the other three patients remained stable during the observation period, and no progression of liver fibrosis was recorded as long as immunosuppressive treatment was continued. Cholestasis and autoimmunity seem to be two important mechanisms triggering hepatic giant cell formation in post-infancy. In the reported cases long-lasting cholestasis in primary sclerosing cholangitis together with features of autoimmune hepatitis seem to have triggered the formation of syncytial hepatic giant cells.

Adrenal Cortex Hormones↗
PubMed1996

Complete reversal of FK 506 induced diabetes in a liver transplant recipient by change of immunosuppression to cyclosporine A.

We report the case of a 41-year old patient who underwent orthotopic liver transplantation because of decompensated liver cirrhosis due to chronic HCV-infection. Severe acute allograft rejection was insufficiently controlled by cyclosporine A, steroids and a 6-day regimen of OKT 3 monoclonal antibody therapy. As a consequence immunosuppressive therapy was switched to FK 506 in a dose of 3 mg bid. The FK 506 concentration in whole blood consistently ranged between 5.1 and 7.8 ng/ml. Seven weeks after the onset of FK 506 therapy the patient developed severe diabetes mellitus with fasting blood glucose levels up to 640 mmol/l. The C-peptide was elevated reflecting a higher than normal insulin secretion. Intravenous insulin therapy with application of up to 85 units regular insulin per day was initiated. Because of the severe diabetes immunosuppression was changed back to cyclosporine A. After six weeks the patient did no longer require insulin and showed an entirely normal glucose tolerance test, C-peptide and Hb A1-level. This case shows that the diabetogenic side effect of FK 506 is more pronounced than that of cyclosporine A. We propose to change immunosuppressive therapy to cyclosporine A in cases of FK 506 induced severe diabetes mellitus, since long-term prognosis of many transplant recipients may depend on side effects of the immunosuppressive agents.

Adult↗
PubMed1995

Lack of requirement for CD8+ cells in recovery from and resistance to experimental autoimmune encephalomyelitis.

Experimental autoimmune encephalomyelitis (EAE) is a model of T-cell mediated autoimmune disease. Active disease is mediated by myelin basic protein specific CD4+ T-cells, whose adoptive transfer can also induce passive disease. In the Lewis rat EAE is a transient disease inducing lasting resistance to rechallenge. The mechanisms of recovery and resistance are poorly understood. CD8+ suppressor T-cells have mostly been thought to be central, especially in resistance to reinduction of the disease. In this study we showed by complete depletion of CD8+ cells that this subset does not influence either recovery or resistance to EAE in the Lewis rat. This was further confirmed by depleting CD8+ cells only after recovery from acute EAE. Such depletion did not diminish the effective resistance to rechallenge. Recovery from and resistance to EAE appear not to require the presence of CD8+ cells.

Animals↗