A.W. Lohse

IL-10 down-regulates T cell activation by antigen-presenting liver sinusoidal endothelial cells through decreased antigen uptake via the mannose receptor and lowered surface expression of accessory molecules.

Our study demonstrates that antigen‐presenting liver sinusoidal endothelial cells (LSEC) induce production of interferon‐gamma (IFN‐γ) from cloned Th1 CD4+ T cells. We show that LSEC used the mannose receptor for antigen uptake, which further strengthened the role of LSEC as antigen‐presenting cell (APC) population in the liver. The ability of LSEC to activate cloned CD4+ T cells antigen‐specifically was down‐regulated by exogenous prostaglandin E2 (PGE2) and by IL‐10. We identify two separate mechanisms by which IL‐10 down‐regulated T cell activation through LSEC. IL‐10 decreased the constitutive surface expression of MHC class II as well as of the accessory molecules CD80 and CD86 on LSEC. Furthermore, IL‐10 diminished mannose receptor activity in LSEC. Decreased antigen uptake via the mannose receptor and decreased expression of accessory molecules may explain the down‐regulation of T cell activation through IL‐10. Importantly, the expression of low numbers of antigen on MHC II in the absence of accessory signals on LSEC may lead to induction of anergy in T cells. Because PGE2 and IL‐10 are released from LSEC or Kupffer cells (KC) in response to those concentrations of endotoxin found physiologically in portal venous blood, it is possible that the continuous presence of these mediators and their negative effect on the local APC may explain the inability of the liver to induce T cell activation and to clear chronic infections. Our results support the notion that antigen presentation by LSEC in the hepatic microenvironment contributes to the observed inability to mount an effective cell‐mediated immune response in the liver.

Prediction of progressive liver fibrosis in hepatitis C infection by serum and tissue levels of transforming growth factor-beta.

Although many patients with chronic viral hepatitis C infection suffer from progressive liver disease, the rate of fibrosis progression is highly variable and some patients do not show any measurable progression. However, our ability to predict which patients progress is very limited. Since transforming growth factor‐β (TGF‐β) is a key mediator of liver fibrogenesis, we assessed the predictive role of TGF‐β for fibrogenesis in chronic hepatitis C. We studied 39 patients with chronic hepatitis C in whom two liver biopsies were taken at least 12 months apart, and who did not receive therapy during this period. TGF‐β was measured by bioassay and by ELISA in serum samples taken at the time of the first biopsies, and TGF‐β was determined semiquantitatively by immunostaining of liver biopsy sections. Fibrosis was scored blinded in the biopsy samples by two pathologists independently. There was a close correlation between TGF‐β serum levels and the rate of fibrosis progression. Patients with no progression of fibrosis had significantly lower (59 ng/mL ± 22) TGF‐β serum levels than patients with progressive disease (115 ng/mL ± 20), and a TGF‐β level below 75 ng/mL was predictive for stable disease. Immunohistology for TGF‐β in biopsy samples was also predictive for progressive liver disease with fibrosis progression found in those patients displaying staining of hepatocytes and sinusoidal cells. No such correlation was found with other markers such as procollagen III peptide, viral load or transaminase levels. These results further support the role of TGF‐β in liver fibrogenesis, and offer an opportunity to predict clinical disease progression, which may help in selecting patients who are in need of therapeutic interventions.

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 P4S0dbl, 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 cells. Five 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 phytohacmagglutinin 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.

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

Abstract 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 respone. 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.

Characterization of liver cytokeratin as a major target antigen of anti-SLA antibodies

Anti-SLA antibodies characterize a newly defined subgroup of patients with autoimmune chronic active hepatitis. The aim of the present study was the immunochemical characterization of the target antigen(s) of anti-SLA antibodies. Anti-SLA-positive sera were found to contain high titres of anti-cytokeratin antibodies. In immunoblotting analyses with 100,000 x g supernatants of human liver homogenates (S-100) these sera recognized various proteins with a molecular mass of 40-60 kDa. These proteins were also recognized by monoclonal anti-cytokeratin antibodies. Two-dimensional co-electrophoresis and immunoblotting analysis of S-100 and liver cytokeratins showed that anti-SLA antibodies were primarily directed against cytokeratins, particularly against liver cytokeratin types 8 and 18. This was supported by affinity chromatography, immunofluorescence and absorption methods using anti-SLA sera.

Clinical modeling of T cell vaccination against autoimmune diseases in rats. Selection of antigen-specific T cells using a mitogen.

Effective T cell vaccination against experimental autoimmune diseases involves treatment with activated, autoimmune T lymphocytes. The present study was undertaken to learn whether antigen-specific T cells present in low frequency could be selected in vitro without using the specific antigen. The rat models of adjuvant arthritis and experimental autoimmune encephalomyelitis were investigated using proliferation assays and limiting dilution techniques to quantify the changes in reactivity of a heterogenous population of lymphocytes to the relevant antigen. Stimulation with concanavalin A for 2 d and then culture in IL-2-containing medium led to a substantial increase in the activity and frequency of the specific autoimmune T cells. Enrichment of antigen-specific T cells could be demonstrated using lymph node, spleen, or peripheral blood lymphocytes, from rats late in the course of disease. The effect was not evident in lymphocytes from the thymus. These results are relevant to the clinical application of T cell vaccination and to investigation of self-antigens in autoimmune disease.

Stimulation of synovial fluid mononuclear cells with the human 65-kD heat shock protein or with live enterobacteria leads to preferential expansion of TCR-γδ+ lymphocytes

T lymphocyte responses to heterologous or self 65‐kD heat shock protein (hsp) have been implicated in the pathogenesis of various forms of arthritis. To delineate the relationship of 65‐kD hsp to different synovial fluid (SF) T cell subsets, we stimulated synovial fluid (SFMC) and peripheral blood mononuclear cells (PBMC) from patients with different inflammatory rheumatic diseases and from healthy controls with human or mycobacterial 65‐kD hsp, tetanus toxoid (TT), heat‐killed or live Yersinia enterocotitica. Phenotyping of the resulting T cell lines revealed an increase of up to 97% TCR‐γδ+ lymphocytes in the 65‐kD hsp‐stimulatcd SF‐derived lines. This expansion of TCR‐γδ+ cells was less pronounced with cultures of PBMC. A preferential expansion of TCR‐γδ+ cells was also shown after SFMC stimulation with live, but not with heat‐killed Yersinia or with TT. We conclude that a common mechanism is involved in the selective expansion of TCR‐γδ+ lymphocytes upon SFMC infection with live Yersinia or upon contact with 65‐kD hsp. Out of a panel of TCR‐γδ+ T lymphocyte clones (TLC) derived from a human 65‐kD hsp‐stimulated line, only a minority of TLC proliferated weakly upon restimulation with this antigen in the presence of autologous monocytes, whereas TCR‐αβ+ TLC responded vigorously to the human 65‐kD hsp and in some cases also cross‐recognized the mycobacterial hsp homologue and/or heat‐killed Yersinia. This implies that additional factors or cells may be present in the milieu of SFMC cultures that propagate the expansion of TCR‐γδ+ cells in response to 65‐kD hsp or live bacteria.

Circadian variations in antigen-specific proliferation of human T lymphocytes and correlation to cortisol production.

Cortisol is a well-known immunosuppressant when used therapeutically. The present investigation was set out to study if diurnal variations in endogenous cortisol production are reflected by changes in proliferative responses of human lymphocytes to either a mitogen (phytohemagglutinin-A, PHA) or an antigen (tetanus toxoid, TT) stimulus. The study included eight healthy volunteers. Blood was withdrawn at 0200, 0600, 1000, and 1800h for preparation of lymphocytes and determination of cortisol in plasma. Isolated cells were incubated without (baseline activity) or with inclusion of either 1 micrograms PHA or 10 micrograms TT. Proliferation was measured by labelling with 3H-thymidine for 16 h of culture. The cortisol plasma levels exhibited the well known diurnal variations with highest concentrations at 1000h and lowest levels at 0200h. Baseline activity or PHA stimulated cell proliferation did not show significant diurnal fluctuations. The response to TT, however, decreased by 38% between 0600 and 1000h (p = .01). Correlation analyses revealed that the reduction of the proliferative responses to TT correlated significantly (p < .05) with increases in cortisol plasma levels. It was concluded that diurnal fluctuations in the production of endogenous cortisol might be relevant for daytime dependent variations in immune responsiveness.

IgG Subclass Distribution of Autoantibodies to Glomerular Basement Membrane in Goodpasture’s Syndrome Compared to Other Autoantibodies

The IgG subclass distribution of autoantibodies to glomerular basement membrane (anti-GBM antibodies) was investigated and compared to the distribution of liver-kidney microsomal (LKM) autoantibodies in chronic active hepatitis, to antimitochondrial autoantibodies (AMA) in primary biliary cirrhosis, and to the subclass distribution of total serum IgG within a healthy population. Solid phase assays for the demonstration of these autoantibodies were performed with four mouse monoclonal antibodies specific for each human subclass to provide quantitative data for the autoantibodies. In addition, the subclass distribution of total IgG in these sera was analyzed. IgG1 accounted for 75% of the total antibody activity in anti-GBM antibodies. In LKM antibodies a more homogeneous distribution was observed between the different subclasses with a relative high proportion of IgG4 autoantibodies (21.2%). In AMA a high proportion of IgG3 subclass autoantibodies was found (anti-p-48 = 28.7%, anti-p-62 = 29.9%). In these patients a high proportion of IgG3 (23 vs. 27.2%) could also be demonstrated in the subclass distribution of total IgG, whereas in patients with anti-GBM antibodies and LKM antibodies the subclass distribution of total IgG was comparable to a population of healthy volunteers. We conclude that the subclass distribution in anti-GBM antibodies differs from the distribution in other autoimmune diseases and from a healthy population and that these differences may be of pathogenetic relevance.

Pneumatoceles and pneumothoraces complicating staphylococcal pneumonia: treatment by synchronous independent lung ventilation.

A 54 year old man with a staphylococcal sepsis developed staphylococcal pneumonia complicated by multiple pneumatoceles and bilateral tension pneumothoraces caused by bronchopleural fistulae. Excessive enlargement of the right sided pneumatoceles and a tension pneumothorax not improved by drainage led to mediastinal shift and compression of the right lung. Reversal of the mediastinal shift and closure of the bronchopleural fistulae was achieved by assisted independent lung ventilation.