bluuebunny/crossref_metadata_2025_split huggingface dataset:
Expression and function of the Fas receptor on human blood and tissue eosinophils
Authors: Hebestreit Holger , Yousefi Shida , Balatti Ivo , Weber Martina , Crameri Reto , Simon Dagmar , Hartung Konrad , Schapowal Andreas , Blaser Kurt , Simon Hans‐Uwe 
Published: March 2007

AbstractThe interaction between activated T cells and eosinophils has been proposed to play an important role in the pathogenesis of allergic diseases. T cell‐derived cytokines such as interleukin‐5 and granulocyte/macrophage colony‐stimulating factor inhibit eosinophil apoptosis and may therefore contribute to the development of tissue and blood eosinophilia in these disorders. Withdrawal of these cytokines leads to eosinophil apoptosis in vitro. In contrast, the mechanisms which actively induce apoptosis in eosinophils are at present not completely understood. In this study, we demonstrate that freshly isolated human eosinophils express mRNA and protein for the Fas receptor. Using anti‐Fas monoclonal antibody (mAb), we show that Fas activation accelerates apoptotic eosinophil death in vitro. Moreover, treatment of nasal polyps ex vivo with anti‐Fas mAb decreased eosinophilic tissue inflammation. However, we observed that blood as well as tissue eosinophils derived from some eosinophilic donors do not express functional Fas receptors, although Fas protein is normally expressed in these cells. This implies that the susceptibility of the Fas receptor is a matter of regulation in eosinophils as previously observed in other systems. These data suggest that Fas ligand/Fas interactions are involved in the regulation of eosinophil apoptosis and that defects in this system could contribute to the accumulation of these cells in allergic and asthmatic diseases.
Phenotypic and functional characterization of CD11c+ dendritic cell population in mouse Peyer's patches
Authors: Ruedl Christiane , Rieser Claudia , Böck Günther , Wick Georg , Wolf Hugo 
Published: March 2007

AbstractThe antigen‐presenting cell system in the gastrointestinal tract, one of three main sites (skin and lung being the others) of primary antigen contact, is poorly understood. Our study focused on dendritic cells (DC) as possible candidates for antigen uptake, processing and presentation in mucosal inductive sites, such as Peyer's patches (PP). To investigate the morphology, immunophenotype and stimulatory activity of intestinal DC, a procedure was developed to obtain a cell population by using collagenase digestion of PP, density centrifugation and cell sorting on the basis of CD11c expression. The resultant low‐density cell fraction consisted of a nonadherent cell population expressing different intensities of CD11c that could at least be characterized by typical DC morphology (e.g. abundant cytoplasma with veil‐like cytoplasmatic dendrites, irregularly shaped nuclei, multivesicular and multilamellar bodies), constitutive levels of surface MHC class II, the presence of macrophage‐specific markers, such as F4/80, Mac‐I and Fc receptors, respectively, on subpopulations of CD11c+ sorted cells and expression of adhesion and co‐stimulatory receptors like ICAM‐1 and CD44. The capability of this low‐density CD11c+ fraction to stimulate T cell responses was demonstrated in primary allogeneic mixed‐lymphocyte reactions (MLR). Herein, we show that the freshly isolated CD11c+ cells showed weak accessory function, but develop this capacity following short‐term culture in vitro in the presence of granulocyte/macrophage colony‐stimulating factor. Although the nature and functional capacity of the isolated CD11c+ needs further clarification, these preliminary results describing phenotype and accessory function provide some evidence that these cells isolated from the PP may be immature forms of DC and play a crucial role as antigen‐presenting cells with important implications for understanding the complex network regulating intestinal antigen uptake, processing and presentation.
Both activated and nonactivated leukocytes from the periphery continuously enter the thymic medulla of adult rats: phenotypes, sources and magnitude of traffic
Authors: Westermann Jürgen , Smith Tomas , Peters Ulrike , Tschernig Thomas , Pabst Reinhard , Steinhoff Gustav , Sparshott Sheila M. , Bell Eric B. 
Published: March 2007

AbstractAlthough the thymus is primarily noted for the export of T cells to the periphery, a small influx of cells has also been observed. It is still a matter of debate whether entry into the thymus depends on prior activation. The phenotypes, sources and degree of immigration are largely unknown. We monitored by quantitative immunohistochemistry the entry of cells from the periphery into the rat thymus in three experimental models. We injected i.v. recirculating, small, nonactivated CD4+ T cell subsets, often referred to as naive (CD45RC+) and memory or antigen‐experienced (CD45RC−) cells, purified from thoracic duct lymph of allotype‐marked donors, allotype‐marked leukocytes released from spleen or lung transplants, or leukocytes labeled in the periphery for 12 weeks during the S‐phase of the cell cycle by oral application of 5‐bromo‐2‐deoxyuridine (BrdUrd). Early after i.v. injection (0.5 h), significantly more antigen‐experienced (CD45RC−) CD4+ T cells entered the thymus, and by 24 h four times as many cells from the CD45RC− subset as from the CD45RC+ subset had entered the thymus and localized to the medulla. None of the thymic entrants expressed the interleukin (IL)‐2 receptor. Following spleen transplantation ∼ 40% of donor cells entering the thymic medulla were T cells and ∼ 55% were B cells. In contrast, from a lung transplant, ∼ 85% of peripheral immigrants were T cells and ∼ 10% were B cells. After both procedures, a small number of NK cells and monocytes/macrophages were found among the immigrants (< 5%). Rats were fed BrdUrd continuously for 12 weeks, a procedure which labeled ∼ 30% of peripheral lymphocytes but not cortical thymocytes. BrdUrd‐labeled cells were localized almost exclusively to the thymic medulla and represented ∼ 10% of medullary cells. Of the thymic immigrants ∼ 50% were T cells, ∼ 30% were B cells (including ∼ 15% IgD+ cells), ∼ 15% were NK cells and the remainder (∼ 5%) were monocytes/macrophages. Only a quarter of BrdUrd‐labeled cells expressed the IL‐2 receptor. The thymus is continuously infiltrated by both activated and nonactivated leukocytes from the periphery, including T cells, B cells, NK cells and monocytes. These immigrants are supplied by lymphoid and nonlymphoid organs in a characteristic subset composition. Their entry is facilitated by prior antigen experience or activation. Thus, the participation of the thymic medulla in general leukocyte traffic suggests a mechanism by which the T cell repertoire could potentially be modulated by the peripheral tissues.
Human eotaxin represents a potent activator of the respiratory burst of human eosinophils
Authors: Elsner Jörn , Höchstetter Renate , Kimmig Daniela , Kapp Alexander 
Published: March 2007

AbstractIncreased numbers of eosinophils are found in parasitic infections, autoimmune diseases and allergic diseases such as allergic asthma. They are activated by distinct cytokines and chemokines leading to the immigration in the inflamed tissue and mediate tissue damage by releasing reactive oxygen species. Here, the effect of the recently cloned CC chemokine human eotaxin was investigated for its ability to affect different eosinophil effector functions and compared to the CC chemokines MCP‐3 and RANTES. Human eotaxin induced chemotaxis of human eosinophils in a dose‐dependent manner. The range of efficacy of the CC chemokines compared to the well‐known chemotaxin C5a was eotaxin = RANTES > MCP‐3 = C5a. In addition, eotaxin induced rapid and transient actin polymerization, a prerequisite for cell migration, in eosinophils in the same range of efficacy as observed for chemotaxis. To investigate whether eotaxin was able to activate the respiratory burst of eosinophils, release of reactive oxygen species was measured by lucigenin‐dependent chemiluminescence. Eotaxin induced production of significantly high amounts of reactive oxygen species at a concentration between 10 ng/ml and 500 ng/ml. Surprisingly, the effect of eotaxin was comparable to the well‐known eosinophil activator C5a. The range of efficacy of the CC chemokines compared to C5a in the activation of the respiratory burst was eotaxin = C5a > MCP‐3 > RANTES. Production of reactive oxygen species was inhibited by pertussis toxin, staurosporin, genestein and wortmannin. Furthermore, eotaxin induced transient increases in intracellular calcium concentration ([Ca2+]i) in human eosinophils. Therefore, pertussis toxinsensitive Gi‐proteins, protein kinase C, tyrosine kinase, phosphatidylinositol‐3‐kinase and transient increases in [Ca2+]i are involved in the signal transduction of eosinophils following stimulation with eotaxin. In summary, this study reveals the importance of the CC chemokine eotaxin as a potent activator of the respiratory burst, actin polymerization and chemotaxis. Eotaxin, therefore, plays an important role not only by attracting eosinophils to the site of inflammation but also by damaging tissue by its capacity to induce the release of reactive oxygen species.
Differential activation requirements of isotype‐switched B cells
Authors: Ehrhardt Rolf O. , Harriman Gregory R. , Inman John K. , Lycke Nils , Gray Belinda , Strober Warren 
Published: March 2007

AbstractIn the present studies, we compared the activation requirements of sIgM+/sIgD+ B cells with those of isotype‐switched sIgM−/sIgA+ B cells. We found that whereas sIgM+ B cells respond to T cell‐independent (TI) and T cell‐dependent (TD) Ag with no significant bias toward one stimulus, sIgA+ B cells were deficient in their ability to respond to antigen receptor cross‐linking but responded remarkably well to TD stimuli. Thus, dextran‐conjugated anti‐IgA antibody (anti‐IgA‐dextran), anti‐kappa‐dextran, or various immobilized anti‐IgA antibodies (Ab) induced only low‐level IgA B cell proliferation and no IgA secretion in the presence of various lymphokines; in marked contrast, sIgA+ B cells responded to cognate and noncognate T cell stimulation as well as to stimulation by CD40 ligand‐bearing fibroblasts by secreting large amounts of IgA (up to 240 000 ng/ml per 105 cells). This pattern of sIgA+ B cell responsiveness was noted with both germinal center peanut agglutininhi (PNAhi) and non‐germinal center PNAlo B cells. In confirmation of these results, whole Peyer's patch or lamina propria cell populations containing less than 15% sIgA+ B cells stimulated with a noncognate T cell stimulus or T cell membranes secreted mainly IgA (68%–94% of the total Ig secreted) and relatively little IgM. The strict T cell dependence of IgA B cell activation and differentiation provides important insights into immune responses of mucosal tissues and must be considered in the development of vaccines, particularly those designed to stimulate mucosal tissues containing large numbers of isotype‐switched B cells.
Expression cloning of the human C3a anaphylatoxin receptor (C3aR) from differentiated U‐937 cells
Authors: Crass Torsten , Raffetseder Ute , Martin Ulrich , Grove Melanie , Klos Andreas , Köhl Jörg , Bautsch Wilfried 
Published: March 2007

AbstractA cDNA clone encoding the human C3a anaphylatoxin receptor (C3aR) was isolated from a pcDNAI/Amp expression library prepared from U‐937 cells which had been differentiated with dibutyryl cAMP to a macrophage‐like phenotype. The cDNA clone contained an insert of 4.3 kbp and was able to confer to transfected human HEK‐293 cells the capacity to bind specifically iodinated human C3a. Chinese hamster ovary cells co‐transfected with this cDNA clone and a G‐protein alpha subunit (Gα‐16) became functionally responsive to C3a and a C3a analog synthetic peptide, as measured by increased phosphoinositide hydrolysis. As inferred from the cDNA sequence, the clone encodes a 482‐residue polypeptide with seven hydrophobic membrane‐spanning helices and a high homology to the human C5a and formyl‐Met‐Leu‐Phe receptors. Uniquely among the family of G‐protein coupled receptors, the C3aR contains an exceptionally large second extracellular loop of approximately 175 residues. Northern hybridizations revealed an approximately 2.3‐kb transcript as the major and an additional ∼ 3.9 kb‐transcript as a minor transcription product of the C3aR. The C3aR appears to be widely expressed in different lymphoid tissues, as shown by Northern hybridizations, providing evidence for a central role of the C3a anaphylatoxin in inflammatory processes.
The functional half‐life of H‐2Kd‐restricted T cell epitopes on living cells
Authors: Eberl Gérard , Widmann Christian , Corradin Giampietro 
Published: March 2007

AbstractThe functional half‐life (t1/2) of different complexes formed by major histocompatibility complex (MHC) class I molecules and antigen on the surface of target cells was measured using specific cytotoxic T lymphocyte (CTL) clones in cytolysis, and interferon‐γ‐production and Ca2+‐mobilization assays. Functional t1/2 values of 5–10 h were obtained, which are in accordance with some previous estimations obtained from biochemical and immunochemical measurements. Moreover, these values were independent of the type of target cell, fixation of the target cells, or proteases able to degrade the peptides, suggesting that the unfolding of the peptide/MHC complexes at the cell surface alone determines the functional t1/2 of the CTL epitopes.
Abnormality of Oct‐1 DNA binding in T cells from Sjögren's syndrome patients
Authors: Flescher Eliezer , Vela‐Roch Norma , Ogawa Noriyoshi , Nakabayashi Toru , Escalante Agustin , Anaya Juan‐Manuel , Dang Howard , Talal Norman 
Published: March 2007

AbstractPrimary Sjögren's syndrome (SS) is an autoimmune rheumatic disease characterized by T cell hypoactivity. To understand the diminished T cell response to activation signals, we measured nucleoprotein DNA‐binding activities regulating gene expression during T cell activation using the electrophoretic mobility shift assay. Peripheral blood lymphocytes from 9/19 SS patients were found to be defective in their ability to bind an octomer sequence (Oct‐1). This Oct‐1‐binding phenotype remained stable in culture for up to 3 days prior to activation. This abnormality was not seen in resting T cells nor T cells from patients with systemic lupus erythematosus, rheumatoid arthritis (RA), or SS accompanied by RA. The SS Oct‐1 DNA‐binding abnormality correlated significantly with an inability of cells to exit the G0/G1 cell cycle phase when stimulated in vitro. Importantly, nucleoprotein extracts showing decreased DNA‐binding activity had normal amounts of Oct‐1 proteins as determined by immunoprecipitation, implying a functional defect in the Oct‐1 protein. Moreover, defective DNA binding was corrected by treatment with acid phosphatase.
T cell responses are governed by avidity and co‐stimulatory thresholds
Authors: Bachmann Martin F. , Sebzda Eric , Kündig Thomas M. , Shahinian Arda , Speiser Daniel E. , Mak Tak W. , Ohashi Pamela S. 
Published: March 2007

AbstractWe analyzed the avidity and CD28‐mediated co‐stimulatory requirements for the activation of T cells in vivo and in vitro. The strength of the T cell/antigen‐presenting cell interaction was varied by using altered peptide ligands for stimulation. Co‐stimulatory requirements were studied using T cells from CD28‐deficient mice. The results indicate that T cell activation is not an all‐or‐nothing event, but occurs in distinct steps. For each step, a certain avidity, co‐stimulatory threshold or both, must be met. Depending upon the strength of the interaction between the T cell receptor and the major histocompatibility complex/peptide and the presence of CD28 co‐stimulatory signals, T cells may undergo blast formation alone or proliferate or eventually both proliferate and differentiate to effector cells. Thus, T cell activation is governed by both avidity and co‐stimulatory thresholds.
Functional analysis of α1β1 integrin in human natural killer cells
Authors: Pérez‐Villar Juan J. , Melero Ignacio , Gismondi Angela , Santoni Angela , López‐Botet Miguel 
Published: March 2007

AbstractUpon activation with interleukin (IL)‐2 human natural killer (NK) cells acquire on their surface the α1β1 and α2β1 integrins and down‐regulate the expression of α6β1. By employing α1β1‐specific monoclonal antibody (mAb) HP‐2B6, characterized in our laboratory, we examined the functional role of the α1β1 integrin in NK cells. Treatment with HP‐2B6 mAb partially interfered with attachment of cultured NK cells to type I collagen, and combined with an anti‐α2β1 (TEA 1/41) mAb, it completely abrogated cell adhesion to this extracelular matrix protein. In contrast, NK cell attachment to laminin was completely blocked by the anti‐β1 LIA 1/2 mAb, but was unaffected by α1 and α2‐specific mAb; as α3β1 and α6β1 were undetectable, the data indicate that the α1β1 integrin binding sites for type I collagen and laminin are different. Incubation with anti‐α1 HP‐2B6 or its F(ab')2 fragments specifically induced a rapid homotypic aggregation of NK cells that was dependent on active metabolism, an intact cytoskeleton and the presence of divalent cations (Ca2+ and Mg2+); homotypic cell adhesion was selectively blocked by anti‐CD18, CD11a or CD54 mAb. In addition, stimulation of cultured NK cells with the anti‐α1 HP‐2B6 enhanced TNF‐α production and induced tyrosine phosphorylation of a 110‐kDa protein. Pretreatment with specific inhibitors of protein tyrosine kinase (PTK) activity (tyrphostin 25 and herbimycin A) completely abrogated the functional effects induced by the anti‐α1 HP‐2B6 mAb. Our data show that ligation of the α1β1 integrin positively modulates IL‐2‐activated NK cell function via a PTK‐dependent pathway.
A shift to Th0 cytokine production by CD4+ cells in human longevity: Studies on two healthy centenarians
Authors: Paganelli Roberto , Scala Enrico , Rosso Rosamaria , Cossarizza Andrea , Bertollo Lorella , Barbieri Daniela , Fabrizi Assunta , Lusi Elena A. , Fagiolo Umberto , Franceschi Claudio 
Published: March 2007

AbstractCentenarians, particularly healthy centenarians, constitute the example of successful aging and the study of their immune status can help to define the endpoint of the changes occurring throughout life. We characterized T cell clones (TCC) of two healthy centenarians, studying their phenotypes and production of representative Th1 and Th2 cytokines (IFN‐γ and IL‐4) and compared them with TCC obtained by three young normal subjects; in all 180 TCC were analyzed. In young donors, 35TCC were CD4+, 56 CD8+ and 2 were αβ4CD4−CD8− (double negative). In centenarians, we obtained 46 CD4+ TCC, 38 CD8+, 2 CD4+CD8+ (double positive) and 1 γδ+ double negative. Of the young subjects' TCC, 71% produced IFN‐γ but no IL‐4 (Th1 pattern) and this prevalence decreased to 39% in TCC from the centenarians. The number of clones showing the opposite Th2 pattern was similar in young and aged donors (3 out of 93 TCC and 2 out of 87 TCC, respectively). The intermediate profile of TCC producing both IL‐4 and IFN‐γ (Th0) was found in 25.8% of clones from young people, but it almost doubled to 58.6% in centenarians. The analysis shows that the Th profiles of CD8+ TCC is nearly superimposable in the two groups, whereas a major shift from a Th1 to a Th0 pattern is presented by CD4+ TCC. The balance provided by a majority of CD4+ TCC showing a Th0 pattern may ensure both humoral and cell‐mediated defences. In CD8+ TCC, however, a Th1 pattern still is present, possibly for efficient generation of cytotoxic responses. These findings should be extended by studying other centenarians and elderly subjects.
In interleukin‐4‐deficient mice, alum not only generates T helper 1 responses equivalent to Freund's complete adjuvant, but continues to induce T helper 2 cytokine production
Authors: Brewer James M. , Conacher Margaret , Satoskar Abhay , Bluethmann Horst , Alexander James 
Published: March 2007

AbstractThe role of interleukin (IL)‐4 in the activity of two frequently used vaccine adjuvants, Freund's complete adjuvant (FCA) and the aluminum hydroxide gels (alum), was studied using the standard antigen ovalbumin (OVA) in IL‐4 genedisrupted mice (IL‐4 ‐/‐). In the absence of adjuvant, there was an overall reduction in antibody production to OVA in IL‐4 −/− mice and significantly greater amounts of interferon (IFN)‐γ were produced following restimulation of splenocytes with antigen in vitro compared with immunocompetent controls (IL‐4 +/+). FCA and alum boosted the immune response to OVA in both IL‐4 −/− and IL‐4 +/+ mice. In IL‐4 +/+ mice, while FCA stimulated a wide‐spectrum immunoglobulin response, including both Th1‐associated IgG2a and Th2‐associated IgG1, alum enhanced only Th2 antibody production and no OVA‐specific IgG2a could be detected. In IL‐4‐deficient mice, however, not only was IgG2a production increased in all adjuvant‐treated groups, but alum was as potent at stimulating this antibody subclass as FCA. Similarly, increased production in vitro by splenocytes of the Th1 cytokine IFN‐γ, equivalent to that produced after inoculation with FCA/OVA, was only detected in IL‐4 −/− mice inoculated with alum/OVA. There was no IgE production in IL‐4 −/− mice and OVA‐specific IgG1 production, although still at significant levels, was reduced compared with wild‐type mice irrespective of the adjuvant used. However, although production of the Th2 cytokine IL‐5 was totally inhibited in IL‐4‐deficient mice inoculated with FCA/OVA, there was no significant difference in IL‐5 production between the two strains when alum was used as adjuvant.
Organ‐specific contribution to circulating C7 levels by the bone marrow and liver in humans
Authors: Naughton Michael A. , Walport Mark J. , Würzner Reinhard , Carter Martyn J. , Alexander Graeme J. M. , Goldman John M. , Botto Marina 
Published: March 2007

AbstractMany cells types can produce complement component C7, although the major site of C7 synthesis is unknown. Conversion from recipient to donor allotype following organ transplantation has demonstrated the synthetic sites of several complement proteins, but in the case of C7 this was not possible until recently. A novel C7 polymorphism (C7 M/N) has been described based on the reactivity with the monoclonal antibody WU 4–15 which identifies in allotype of C7 (C7 M). Bone marrow and hepatic C7 production was quantified in bone marrow transplant and liver transplant recipients, respectively, where a mismatch for the C7 allotypes distinguished by the monoclonal antibody had occurred. In the bone marrow transplant group, one informative transplant was identified and donor‐derived C7 was detected by enzyme‐linked immunosorbent assay. It contributed to 18–27% of the total circulating C7 during the post‐transplant phase and was increased during episodes of inflammation. In the liver transplant group, the hepatic contribution to the C7 levels were 30% and 52%, respectively, in two patients identified prospectively. A further three informative liver transplant patients were identified retrospectively and in these individuals, 56–62% of the circulating C7 was liver‐derived. This study demonstrates that the majority of the circulating C7 is derived from the liver and bone marrow with a lesser contribution from other sources. These findings provide further support for the concept that locally secreted complement proteins have an important role in inflammation.