bluuebunny/crossref_metadata_2025_split huggingface dataset:
Redox imbalance and immune functions: opposite effects of oxidized low‐density lipoproteins and N‐acetylcysteine
Authors: Viora Marina , Quaranta Maria Giovanna , Straface Elisabetta , Vari′ Rosaria , Masella Roberta , Malorni Walter 
Published: March 2003

SummaryThis study investigates the in vitro effects of oxidized low‐density lipoproteins (ox‐LDL), ‘physiological’ pro‐oxidants, N‐acetylcysteine (NAC), a free radical scavenger and glutathione precursor, and their combination on human peripheral blood mononuclear cell functions. We found that treatment with ox‐LDL induced a significant down‐regulation of proliferative response to mitogens, antigens and interleukin‐2. Lipid extracts from ox‐LDL were able to reproduce the same effect as the lipoprotein. On the other hand, NAC exposure induced a significant up‐regulation of proliferative responses to all the stimuli used. Moreover, we showed that natural killer (NK) cell‐mediated cytotoxic activity was significantly down‐regulated by ox‐LDL while treatment with NAC induced a significant up‐regulation of NK‐cell activity. Finally, we found that ox‐LDL and NAC exerted opposite effects on the cytokine network, interfering both at the protein secretion level and the messenger RNA synthesis level. More importantly, when NAC was used in combination with ox‐LDL the proliferative responses, NK‐cell‐mediated cytotoxic activity and cytokine production were restored to values comparable to controls. These data indicate that ox‐LDL and NAC modulate immune functions, exerting opposite effects reflecting their pro‐oxidant and antioxidant behaviours. Our results add new insights to the key role played by redox imbalance as a modulator of immune system homeostasis and suggest that an antioxidant drug such as NAC could be useful against pathologies associated with an increase in lipid peroxidation.
Rapid changes in the lymphopoietic and granulopoietic compartments of the marrow caused by stress levels of corticosterone
Authors: Laakko Tonya , Fraker Pamela 
Published: March 2003

SummaryExposure to concentrations of glucocorticoids analogous to those produced during stress, trauma and malnutrition had rapid but varying effects on the major classes of cells within the marrow. Corticosterone (CS) was given as a subdermal implant in young mice and generated 60–95 µg CS/dl of blood compared to 5–15 µg CS/dl for sham controls over a period of 36 hr. Within 24 hr CS had caused losses of 30–70% among the early pro‐B, pre‐B and immature B cells. The pre‐B cells were virtually eliminated by 36 hr and the capacity of surviving pro‐ and pre‐B cells to cycle was reduced by 70–80%. Interestingly, the earliest of B cells, the prepro‐B cells, showed considerable resistance to CS, being reduced by only 20% at 36 hr. Thus, the pattern of survival within the B‐cell compartment paralleled the expression of Bcl‐2. At the 36‐hr time‐point there were no changes in the proportion of progenitor cells, erythroid or monocytic cells, or number of nucleated cells in the marrow. By contrast, 36 hr after exposure to CS there was an increase of 30% in the proportion and absolute number of cells in the granulocytic compartment. Chronic production of CS appears to reprogramme lymphopoiesis and myelopoiesis, perhaps to preserve the first line of immune defence at the expense of the lymphoid branch. Resistance to apoptosis and modifications in the activity of the glucocorticoid receptor and cytokines produced by stromal cells are postulated as targets for CS‐driven changes.
Expression of caveolin by bovine lymphocytes and antigen‐presenting cells
Authors: Harris James , Werling Dirk , Koss Michael , Monaghan Paul , Taylor Geraldine , Howard Chris J. 
Published: March 2003

SummaryCaveolin is a generic term for a family of proteins that include caveolin‐1, ‐2 and ‐3. Although the distribution of these proteins varies between cells, caveolin‐1 and ‐2 are commonly found coating membrane invaginations known as caveolae. Studies on human and murine cells suggest that caveolin/caveolae can be found in neutrophils, macrophages and mast cells, in which they are involved in the uptake of pathogens, but not in lymphocyte cell lines. Expression of caveolin‐1, ‐2 and ‐3 in bovine immune cells was investigated using confocal microscopy and Western blotting. Staining for caveolin‐1 was evident in all peripheral blood mononuclear cells (PBMC) and in CD4+, CD8+ and CD21+ lymphocytes, monocytes, macrophages and monocyte‐derived dendritic cells (DC). In addition, the caveolin‐1 antibody detected a protein with a molecular weight of approximately 22 000 in all PBMC, macrophages and DC, as well as in bovine aortic endothelial (BAE)‐1 cells and human endothelial cells by Western blotting. In macrophages and DC, caveolin co‐localized with the endoplasmic reticulum–Golgi intermediate compartment (ERGIC) and to a lesser extent with Golgi, but not with endoplasmic reticulum. Staining was not seen on the plasma membrane in any bovine immune cells, suggesting the absence of caveolae, while in BAE‐1 cells staining was predominantly on the cell membrane. Caveolin‐2 could not be detected in any bovine cells by confocal microscopy or Western blotting, while caveolin‐3 was detected in all bovine cells by Western blotting, but not by confocal microscopy. These data provide evidence for the presence of caveolin in bovine lymphocytes and antigen‐presenting cells.
Induction of thymocyte positive selection does not convey immediate resistance to negative selection
Authors: Hare Katherine J. , Pongracz Judit , Jenkinson Eric J. , Anderson Graham 
Published: March 2003

SummaryThe acquisition of functional competence represents a critical phase during intrathymic development of T cells. Thymocytes reaching this stage represent cells which have been positively selected on the basis of major histocompatibility complex reactivity, but which have also been purged of potentially autoreactive T‐cell receptor specificities by negative selection. While the developmental window in which thymocytes are subjected to positive selection is now well defined, the precise developmental timing of negative selection, in relation to positive selection events, is less clear. Moreover, the underlying mechanism allowing single‐positive thymocytes to respond to T‐cell receptor ligation by activation rather than death, remains controversial. Here we have analysed the developmental timing of negative selection in relation to positive selection, using measurement of thymocyte susceptibility to dendritic cell presentation of the superantigen staphylococcal enterotoxin B (SEB). We show that thymocytes which have received initial positive selection signals, namely CD4+ CD8+ CD69+ thymocytes, like their CD4+ CD8+ CD69− precursors, are susceptible to negative selection, indicating that induction of positive selection does not convey immediate resistance to negative selection. In contrast, newly generated CD4+ CD8− CD69+ cells are not only resistant to deletion by SEB, but respond to SEB‐mediated T‐cell receptor‐ligation by activation, indicating that the acquisition of functional competence occurs at the newly generated CD4+ CD8− CD69+ stage. Finally, by using direct retroviral infection of primary CD4+ CD8+ thymocytes, we also show that Notch‐1 activation in CD4+ CD8+ thymocytes does not correlate with, nor convey resistance to superantigen‐mediated negative selection. Thus, our data suggest that although Notch‐1 has been implicated in resistance to thymocyte apoptosis, the acquisition of resistance to negative selection occurs independently of Notch‐1 signalling.
Lung dendritic cells are primed by inhaled particulate antigens, and retain MHC class II/antigenic peptide complexes in hilar lymph nodes for a prolonged period of time
Authors: Vu Quynh , McCarthy Karin M. , McCormack Joanne M. , Schneeberger Eveline E. 
Published: March 2003

SummaryIntratracheal (IT) administration of heat‐killed Listeria monocytogenes (HKL) results in an influx of macrophage and dendritic cell (DC) precursors into the lung interstitium. Low‐density, FcR+, interstitial lung cells isolated from rats instilled 24 hr before with HKL or vehicle alone, were > 90% Mar1+. After culturing with granulocyte–macrophage colony‐stimulating factor (GM‐CSF) for 3 days, up to 24% of the loosely adherent cells were DC that stimulated allogeneic T‐cell proliferation in an mixed lymphocyte reaction (MLR) assay. After only an overnight incubation with GM‐CSF, however, the capacity of interstitial Mar1+ cells to stimulate HKL immune T‐cell proliferation without exogenous antigen was low. By contrast, when DC were isolated as major histocompatibility complex (MHC) class II+ cells from rat lungs at 1, 3, 7 and 14 days after HKL instillation and cultured overnight with GM‐CSF, their antigen presentation capacity without added exogenous antigen was robust, but declined over the 2‐week period. Interestingly, hilar lymph node DC maintained their HKL antigen‐presenting capacity for up to 2 weeks after instillation of HKL. Following IT administration of PKH‐26 labelled HKL, fluorescent or immunolabelled organisms were detected in OX62+ DC in airway epithelium, lung interstitium and hilar lymph nodes in situ and in MHC class II+ DC isolated from these sites. We conclude that newly immigrated Mar1+ lung DC precursors, while efficient in endocytosing particulate antigens, are incapable of eliciting a significant proliferative response from HKL‐sensitized T cells. By contrast, MHC class II+ DC isolated from lungs and incubated overnight with GM‐CSF induce vigorous antigen‐specific T‐cell proliferation. Antigen‐loaded lung DC in hilar lymph nodes maintain their antigen presentation capacity for up to 2 weeks.
Human monoclonal natural autoantibodies against the T‐cell receptor inhibit interleukin‐2 production in murine T cells
Authors: Robey Ian F. , Schluter Samuel F. , Akporiaye Emmanuel , Yocum David E. , Marchalonis John J. 
Published: March 2003

SummaryNatural autoantibodies (NAAbs) specific for the T‐cell receptor (TCR) are present in all human sera, but individuals with rheumatoid arthritis (RA) generally produce higher titres of immunoglobulin M (IgM) isotype autoantibodies (AAbs) against Vβ TCR epitopes. To investigate possible correlations between the specificity of such AAbs and their role in immunomodulation, we generated seven B‐cell hetero‐hybridomas, secreting monoclonal IgM NAAbs, from the synovial tissue and peripheral blood of patients with RA. Here we report three anti‐TCR monoclonal autoantibodies (mAAbs) – OR2, OR5 and Syn 2H‐11 – with the ability to bind subsets of murine T cells, including the ovalbumin‐specific DO‐11.10 clone. These antibodies did not induce apoptosis in vitro, but prevented interleukin‐2 (IL‐2) production by antigen‐specific T cells. These findings suggest an immunomodulatory function for NAAbs to TCR V‐region epitopes and serve as the foundation for testing human anti‐TCR mAAbs in animal models with the eventual goal of using them as therapeutic agents in human disease.
HeLa cells cocultured with peripheral blood lymphocytes acquire an immuno‐inhibitory phenotype through up‐regulation of indoleamine 2,3‐dioxygenase activity
Authors: Logan Grant J. , Smyth Christine M. F. , Earl John W. , Zaikina Irina , Rowe Peter B. , Smythe Jason A. , Alexander Ian E. 
Published: March 2003

SummaryThe mechanisms by which tumour cells escape recognition by the immune system or subvert antitumour effector responses remain poorly understood. In the course of investigating the potential of costimulatory signals in anticancer immunotherapy strategies, we have observed that HeLa cells (a human cervical carcinoma cell line) cocultured with peripheral blood lymphocytes (PBL) acquire the capacity to inhibit PBL proliferation in response to interleukin‐2 (IL‐2). This immuno‐inhibitory phenotype was further shown to result from induction of the tryptophan‐catabolizing enzyme, indoleamine 2,3‐dioxygenase (IDO), by interferon‐γ (IFN‐γ) secreted from cocultured allo‐reactive PBL. This enzyme has recently been shown to be a critically important modulator of immunological responses, most notably through the capacity to protect allogeneic concepti from alloreactive maternal lymphocytes. While the cytostatic consequences of IDO activity in tumour cells has received attention, the data presented in this report support the hypothesis that IDO activity may also act to impair antitumour immune responses.
Modulation of human monocytes by Escherichia coli heat‐labile enterotoxin B‐subunit; altered cytokine production and its functional consequences
Authors: Turcanu Victor , Hirst Timothy R. , Williams Neil A. 
Published: March 2003

SummaryIn murine systems, the B subunit of Escherichia coli heat‐labile enterotoxin (EtxB) is a potent immunomodulator capable of suppressing Th1‐mediated autoimmune diseases. This results from its ability to bind cell surface receptors, principally GM1‐ganglioside, and as a consequence down‐regulate the pathological T helper type 1 (Th1) response. The capacity of EtxB to alter human T‐cell responses has not been investigated. Here we show that EtxB, but not the receptor non‐binding mutant EtxB (G33D), triggers the release of interleukin (IL)‐10, IL‐6 and tumour necrosis factor‐α (TNF‐α) by human monocytes. The production of IL‐8, transforming growth factor‐β (TGF‐β) or IL‐12 was not enhanced by EtxB. Indeed, EtxB was shown to inhibit IL‐12 secretion in monocytes stimulated with interferon‐γ (IFN‐γ) and lipopolysaccharide (LPS) by an IL‐10‐independent mechanism. When EtxB‐treated monocytes were used as antigen presenting cells in an allogeneic mixed lymphocyte reaction (MLR), IL‐10 and IFN‐γ production were increased in comparison to levels seen in cultures stimulated with untreated monocytes; proliferation was unaltered. This modulation of the T‐cell response was not only evident in the primary MLR triggered by EtxB‐treated monocytes, but also upon restimulation of the responding T cells with fresh untreated monocytes; indicating that presentation by EtxB‐treated monocytes leads to altered T‐cell differentiation. Sorting experiments showed that IL‐10 secreting T cells from the MLR cultures were strong suppressors of T‐cell proliferation following their addition into a fresh primary MLR.
The ability of antigen, but not interleukin‐2, to promote n‐butyrate‐induced T helper 1 cell anergy is associated with increased expression and altered association patterns of cyclin‐dependent kinase inhibitors
Authors: Jackson Stephanie K. , DeLoose Annick , Gilbert Kathleen M. 
Published: March 2003

SummaryThe ability of the cell cycle inhibitor n‐butyrate to induce T helper 1 (Th1) cell anergy is dependent upon its ability to block the cell cycle progression of activated Th1 cells in G1. Results reported here show that although both interleukin (IL)‐2 and antigen (Ag) push Th1 cells into G1 where they are blocked by n‐butyrate, only the Ag‐activated Th1 cells demonstrate functional anergy once the n‐butyrate has been removed from the culture. Because n‐butyrate‐induced Th1 cell anergy has been linked to increased expression of the cyclin‐dependent kinase inhibitors p21Cip1 and p27Kip1, mechanistic experiments focused on the role of these inhibitors. It was found that when Th1 cells were reincubated in Ag‐stimulated secondary cultures, the Th1 cells previously exposed to Ag and n‐butyrate (anergic Th1 cells) demonstrated a cumulative increase in p21Cip1 and p27Kip1 when compared with Th1 cells previously exposed to recombinant (r)IL‐2 and n‐butyrate (non‐anergic Th1 cells). p27Kip1 in the anergic Th1 cells from the secondary cultures was associated with cyclin‐dependent kinases (cdks). In contrast, p21Cip1 in the anergic Th1 cells, although present at high levels, did not associate significantly with cdks, suggesting that p21Cip1 may target some other protein in the anergic Th1 cells. Taken together, these findings suggest that Th1 cell exposure to Ag and n‐butyrate, rather than IL‐2 and n‐butyrate, is needed to induce the cumulative increase in p21Cip1 and p27Kip1 that is associated with the proliferative unresponsiveness in anergic Th1 cells. In addition, p21Cip1 may inhibit proliferation in the anergic Th1 cells by some mechanism other than suppression of cdks that is unique to the induction of Th1 cell anergy.
Long‐term kinetics of adult human antibody repertoires
Authors: Van Dijk‐Härd Iris , Lundkvist Inger 
Published: March 2003

SummaryIn healthy humans, antibody repertoires change during ontogeny and senescence. The dynamics of antibody repertoires among adults over a longer period of time in one and the same individual has, however, not been extensively studied. In this study we analysed peripheral blood samples from five healthy adults, taken over a period of 10 weeks and once 9 years later. A competitive, quantitative polymerase chain reaction (PCR) was developed to investigate short and long‐term variations in VH gene family repertoires. Serum antibody levels to common self and non‐self antigens were determined in samples taken at the same time‐points as the cell samples to analyse possible correlations between molecular and serological expression profiles. We found a high degree of stability in the VH gene family repertoire over time as well as between individuals with a Caucasian background. A specific change in the usage of primarily the VH3 and VH5 gene families was observed in one individual at one time‐point. The deviating pattern resembled the VH gene family utilization pattern observed in naturally activated B lymphocytes. The fluctuations in VH3 and VH5 gene family expression correlated with the presence of rheumatoid factor in serum. We discuss the possible influence of polyclonal, transient stimulation of B cells on VH gene repertoires, as measured in circulating B cells.
Loxosceles spider venom induces metalloproteinase mediated cleavage of MCP/CD46 and MHCI and induces protection against C‐mediated lysis
Authors: Van Den Berg Carmen W. , De Andrade Rute M. Gonçalves , Magnoli Fabio C. , Marchbank Kevin J. , Tambourgi Denise V. 
Published: March 2003

SummaryWe have recently shown that sphingomyelinase D toxins from the spider Loxosceles intermedia induce Complement (C) ‐dependent haemolysis of autologous erythrocytes by the induction of cleavage of cell‐surface glycophorins through activation of a membrane‐bound metalloproteinase. The aim of this study was to investigate the effects of these toxins on C‐regulator expression and the C‐resistance of nucleated cells. Cells were incubated with Loxosceles venom/toxins and the expression of C‐regulators was assessed by flow cytometry. A reduced expression of membrane co‐factor protein (MCP) was observed, while expression of decay‐accelerating factor (DAF) and CD59 was not affected. Analysis of other cell‐surface molecules showed a reduced expression of major histocompatibility complex I (MHCI). Western blotting showed that a truncated form of MCP was released into the supernatant. Release could be prevented by inhibitors of metalloproteinases of the adamalysin family but not by inhibitors specific for matrix metalloproteinases. Cleavage of MCP was induced close to or within the membrane as demonstrated by the cleavage of transmembrane chimeras of CD59 and MCP. Although the venom/toxins induced a release of MCP, the C‐susceptibility was decreased. The mechanism of this induction of resistance may involve a change in membrane fluidity induced by the sphingomyelinase activity of the toxin/venom and/or involvement of membrane‐bound proteases. The soluble forms of MCP found in tissues and body under pathological conditions like cancer and autoimmune diseases may be released by a similar mechanism. The identity of the metalloproteinase(s) activated by the spider venom and the role in pathology of Loxoscelism remains to be established.
Maternal cell traffic bounds for immune modulation: tracking maternal H‐2 alleles in spleens of baby mice by DNA fingerprinting
Authors: Wan Wenhan , Shimizu Shoji , Ikawa Hiromichi , Sugiyama Kiyosh , Yamaguchi Nobuo 
Published: March 2003

SummaryWe have previously reported that the immunization of pregnant mice with T‐dependent antigens successfully induced suppression of the antigen‐specific plaque‐forming cell (PFC) response to the relevant antigens in the offspring. This suppression was not caused by the administered antigens, the antibodies produced by the pregnant mother, or lactational transfer, but was dependent on the presence of the intact maternal T cells. It was major histocompatibility complex (MHC)‐restricted manner tolerance, which continued for at least one‐sixth of the murine life. Traditionally, the placenta acts as a natural barrier, not allowing the cells to pass through. However, the results presented strongly suggested that maternal T cells pass through the placenta and subsequently induce tolerance. In this present study, we attempted to substantiate the presence of maternal cells in the fetal circulation through the use of molecular techniques. We found that a highly polymorphic microsatellite sequence within the class II Eb gene of the H‐2 complex is useful for the molecular detection of various H‐2 alleles. DNA polymorphic analysis was used for tracking maternal H‐2 alleles in the spleens of baby mice. The main procedure involved polymerase chain reaction amplification and restriction fragment length polymorphism analysis of the DNA sequence encompassing the H‐2‐specific microsatellite from the genomic DNA of baby mice. The results indicated that maternal T cells of immunized pregnant mice cross the placenta into the fetus, eventually inducing antigen‐specific immunological tolerance in the offspring.
Human autologous mixed lymphocyte reaction as an in vitro model for autoreactivity to apoptotic antigens
Authors: Amel Kashipaz Mohammad R. , Huggins Mary L. , Powell Richard J. , Todd Ian 
Published: March 2003

SummaryRecent studies have indicated that cells undergoing apoptosis are the source of autoantigens which drive autoimmune responses in systemic lupus erythematosus (SLE). It has been recognized for many years that in vitro stimulation of T cells with irradiated major histocompatibility complex (MHC) class II‐bearing autologous cells results in T‐cell proliferation with immunological specificity and memory, namely the autologous mixed lymphocyte reaction (AMLR). The nature of the major stimulants in the AMLR is still unclear. We investigated whether apoptotic fragments from irradiated cells act as antigenic stimulators for AMLR or nucleohistone‐primed T cells. T‐cell proliferation in the primary AMLR was significantly suppressed by the presence of a caspase inhibitor Z‐Val‐Ala‐Asp‐CH2F (Z‐VAD.fmk), indicating that apoptotic antigens released from irradiated autologous feeder cells act as stimulators of AMLR T cells. This inhibitory effect of Z‐VAD was not caused by toxic effects, because the T‐cell response to the mitogen phytohaemagglutinin (PHA) was not inhibited by Z‐VAD. A nucleohistone preparation was shown to contain antigens that are important in the AMLR, as culture with nucleohistone (but not with thyroglobulin or hen‐egg lysozyme) primed T cells to respond with secondary kinetics in a subsequent AMLR that was also suppressed by Z‐VAD. Our data provide evidence that the AMLR constitutes a model for the evaluation of cellular and molecular mechanisms that may be relevant to the pathogenesis of SLE and similar autoimmune diseases.