bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differential contribution of thymic outputs and peripheral expansion in the development of peripheral T cell pools
Authors: Modigliani Yves , Coutinho Graça , Burlen‐Defranoux Odile , Coutinho Antonio , Bandeira Antonio 
Published: March 2007

AbstractThe number of peripheral T cells in mice increases up to 100‐fold in the first few weeks of life. We have followed the fate of Thy‐1 congenic T cells transferred into newborn recipients, to evaluate the relative contribution of thymic output versus peripheral expansion in the constitution of peripheral T cell pools during post‐natal development. The results show that in normal animals there is essentially no peripheral expansion of T cells, which show slow turnover rates (1 to 2 months) along that time period. The rates of cell accumulation in the periphery require, therefore, an average of 1 × 106−2 × 106 mature thymic emigrants/day for the first 3 weeks of life.
Effect of CTLA‐4 chimeric protein on rat autoimmune anti‐glomerular basement membrane glomerulonephritis
Authors: Nishikawa Kazuhiro , Linsley Peter S. , Collins A. Bernard , Stamenkovic Ivan , McCluskey Robert T. , Andres Giuseppe 
Published: March 2007

AbstractThe interaction of the T cell receptor with the antigen/major histocompatibility class II complex is insufficient to induce optimal T cell activation. Co‐stimulatory signals, including those provided by CD28/CTLA‐4 on T cells and B7 molecules (B7‐1, −2 and −3) on antigen‐presenting cells, are also required. CD28‐B7 interactions can be blocked by a soluble human CTLA‐4 chimeric protein (CTLA4Ig). We tested the effect of administration of CTLA4Ig on experimental anti‐glomerular basement membrane (GBM) autoimmune glomerulonephritis in Wistar‐Kyoto rats induced by immunization with bovine GBM. The disease is characterized by development of antibody to the α3 chain of type IV collagen (Goodpasture's antigen), deposition of rat IgG in GBM, infiltration of the kidney by T cells and macrophages, severe crescent formation and renal failure leading to death in 5–6 weeks. Animals injected with human CTLA4Ig from day 0 to day 14 or to day 35 had reduced disease severity. Beneficial effects were observed even when injections were begun after the onset of glomerulonephritis on day 14. However, the rats developed antibody to the human CTLA4Ig, associated with reduction in levels of circulating CTLA4Ig. The results provide evidence for CD28/CTLA‐4 signaling in rat autoimmune glomerulonephritis, and suggest that more effective inhibition of B7‐dependent T cell activation, such as might be achieved with homologous CTLA4Ig, could be useful in the treatment of autoimmune diseases.
Lipopolysaccharide‐induced cytokine production in human monocytes: Role of tyrosine phosphorylation in transmembrane signal transduction
Authors: Beaty Christopher D. , Franklin Terry L. , Uehara Yoshimasa , Wilson Christopher B. 
Published: March 2007

AbstractThe signal transduction events that follow the binding of lipopolysaccharide (LPS) to the macrophage cell surface are not well defined. In the current studies LPS was found to induce alterations in phosphorylation of monocyte proteins on tyrosine. Herbimycin A and genistein, inhibitors of tyrosine kinases, markedly attenuated LPS‐induced tumor necrosis factor‐α (TNF‐α) and interleukin‐6 (IL‐6) protein and mRNA production. Reciprocally, the tyrosine phosphatase inhibitor sodium orthovanadate enhanced LPS‐induced production of TNF‐α. LPS induced a concentration‐dependent increase in tyrosine phosphorylation of several proteins, which paralleled and preceded the onset of LPS‐induced TNF‐α production. LPS stimulation had different but reproducible effects on three members of the src family of tyrosine kinases. Both Hck and Lyn kinase activity increased before the onset of TNF‐α production, consistent with their participation in the observed LPS‐induced tyrosine phosphoprotein accumulation. In contrast, Yes kinase activity was not affected. These observations were made at concentrations of LPS that required serum rich in LPS‐binding protein and the monocyte surface antigen CD14 for TNF‐α production. These data indicate that tyrosine kinases and phosphatases are involved in the signal transduction cascade by which LPS induces production of TNF‐α and IL‐6 by human monocytes, and suggest that Lyn and Hck are candidate participants in this process.
Cytokine synthesis and apoptosis by intestinal intraepithelial lymphocytes: Signaling of high density αβ T cell receptor+ and γδ T cell receptor+ T cells via T cell receptor‐CD3 complex results in interferon‐γ and interleukin‐5 production, while low density T cells undergo DNA fragmentation
Authors: Yamamoto Masafumi , Fujihashi Kohtaro , Amano Masahiko , McGhee Jerry R. , Beagley Kenneth W. , Kiyono Hiroshi 
Published: March 2007

AbstractTo study the biological consequences of cytokine production and apoptosis by intraepithelial lymphocytes (IEL), we have studied these characteristics in both the high and low density CD3+ IEL populations. Stimulation of low‐ or high‐density CD3+ IEL via the T cell receptor (TCR)‐CD3 complex using monoclonal anti‐CD3, anti‐αβ TCR or anti‐γδ TCR antibodies resulted in opposing effects. In one case, a significant number of the high‐density CD3+ T cells entered cell cycle from the resting stage (DNA replication was observed) and anti‐TCR‐CD3 treatment enhanced the numbers of interferon‐γ and interleukin‐5 spot‐forming cells in this cell fraction. In contrast, when the low‐density αβ TCR+ or γδ TCR+ T cells were activated via the TCR‐CD3 complex, DNA fragmentation was observed. These results demonstrated that the activation signals transduced via the TCR‐CD3 complex resulted in their entry into the cell cycle and subsequent interferon‐γ and interleukin‐5 production in the high‐density IEL T cell subset. However, identical signals induced apoptosis in the majority of the low‐density fraction of CD3+ IEL.
In vivo and in vitro IgE isotype switching in human B lymphocytes: Evidence for a predominantly direct IgM to IgE class switch program
Authors: Van Der Stoep Nienke , Korver Wouter , Logtenberg Ton 
Published: March 2007

AbstractMolecular analysis of circular excision products and composite genomic switch regions has demonstrated that in mice, immunoglobulin (Ig) isotype switching from IgM to IgE often proceeds sequentially via IgG1. Based on analysis of Ig production in cell cultures, it has been suggested that human B cells may switch to IgE via IgG4, whereas limited molecular data from in vitro switched B cells suggest a direct IgM to IgE switch program. To obtain a quantitative assessment of direct versus sequential IgE switching in humans, we have analyzed the nucleotide sequences of 29 composite Sμ/Sϵ switch regions from freshly isolated human B lymphocytes from patients with atopic dermatitis and from B lymphocytes induced to switch to IgE synthesis in vitro. The data show that in these B cells IgE isotype switching progressed directly from IgM to IgE. We conclude that, in contrast to the murine IgM/IgE switch program, the IgM to IgE switch in B lymphocytes from patients with atopic dermatitis as well as in vitro stimulated B cells from healthy donors preferentially proceeds via direct Sμ to Sϵ switch recombination.
Pro‐T cells in fetal thymus express c‐kit and RAG‐2 but do not rearrange the gene encoding the T cell receptor β chain
Authors: Hozumi Katsuto , Kobori Akiko , Sato Takehito , Nozaki Hideki , Nishikawa Shin‐Ichi , Nishimura Takashi , Habu Sonoko 
Published: March 2007

AbstractTen percent of 15‐day fetal thymocytes of mice were Pgp‐1+Thy‐1lo cells. Half were strongly stained with monoclonal antibodies (mAb) recognizing the oncogene product, c‐kit, but were not stained with mAb against non‐T cell markers such as B220, Mac‐1 and Gr‐1. The isolated Pgp‐1+c‐kit+ thymocytes showed no rearranged bands for V‐DJ and D‐J of T cell receptor (TcR) β, but Pgp‐1−‐c‐kit− thymocytes showed D‐J rearranged bands. Both cells expressed the RAG‐2 gene which is required for the V(D)J recombination process. When Pgp‐1+c‐kit+ thymocytes were cultured in 2‐deoxyguanosine‐treated alymphocytic fetal thymus, they became TcR‐expressing mature type T cells, but this differentiation was reduced by the addition of anti c‐kit mAb. These data indicate that Pgp‐1+c‐kit+ thymocytes are pro‐T cells with the potential to differentiate mature T cells in the thymic environment. This study also indicates that c‐kit‐mediated signals promote the differentiation of thymocytes during their early stages.
Intracellular Ca2+ stores of T lymphocytes: Changes induced by in vitro and in vivo activation
Authors: Clementi Emilio , Martino Gianvito , Grimaldi Luigi M. E. , Brambilla Elena , Meldolesi Jacopo 
Published: March 2007

AbstractIntracellular Ca2+ stores were investigated in resting and activated splenic T lymphocytes from Lewis rats. Activation was obtained either in vitro (spleen cells isolated from “naive” rats exposed to concanavalin A for 24 h) or in vivo (spleen cells from rats with fully developed symptoms of experimental allergic encephalomyelitis). In both experimental conditions several changes of Ca2+ homeostasis were observed with respect to resting lymphocytes: (1) a threefold increase of the total intracellular calcium (from 1.15 to 3.5 mmol/l); (2) a moderate increase of the pool sensitive to inositol 1,4,5‐trisphosphate (IP3), investigated both in intact T lymphocytes (fura‐2 and 45Ca2+‐release techniques in cells challenged with phytohemagglutinin) and in T lymphocytes permeabilized with β‐escin (45Ca2+ release induced by saturating concentrations of IP3); and (3) the appearance of a pool released by the endoplasmic reticulum (ER) Ca2+ ATPase inhibitor thapsigargin (Tg), but insensitive to IP3, which, therefore, appears to be localized in areas of the ER devoid of the cognate receptor. The latter two findings were paralleled in activated lymphocytes by an increase of expression of ER markers, involved (calreticulin; Ca2+ ATPase) or not (protein disulfide isomerase) in the regulation of Ca2+ homeostasis. In contrast, calnexin (another ER marker) and the receptor for IP3 were increased to only a moderate extent. Finally, an enlargement of non‐ER Ca2+ pools was observed in the cells pretreated with Tg in which 45Ca2+ release was induced by the Ca2+ ionophore ionomycin. Our results document structural and functional changes of intracellular Ca2+ stores which might play an important regulatory role in activated T lymphocytes.
Soluble transferrin mediates targeting of hepatitis B envelope antigen to transferrin receptor and its presentation by activated T cells
Authors: Gagliardi Maria‐Cristina , Nisini Roberto , Benvenuto Rosalba , De Petrillo Guido , Michel Marie‐Louise , Barnaba Vincenzo 
Published: March 2007

AbstractIn a previous study, we identified that transferrin receptor (TfR) is the receptor utilized by hepatitis B virus (HBV) to enter T cells. We demonstrated that hepatitis B envelope antigen (HBenv Ag) is taken up by activated T cells via TfR, processed in endosomal compartments, and presented on class II molecules to specific CD4+ T cell clones. Herein, we report that binding to soluble ferric Tf by HBenv Ag is needed in TfR‐mediated endocytosis. Accordingly, presentation of HBenvAg by activated T cells is not observed in serum‐free medium and is restored by addition of soluble Tf. Moreover, we provide evidence that pre‐S2 and S regions of HBenv Ag contain the critical residues for the interaction with soluble Tf. Our data not only explain HBV entry into a variety of host activated cells, but may also help in developing strategies to alter the course of chronic HBV infection.
Human CD45RA+ and CD45R0+ T cells exhibit similar CD3/T cell receptor‐mediated transmembrane signaling capacities but differ in response to co‐stimulatory signals
Authors: Schwinzer Reinhard , Siefken Renate , Franklin Richard A. , Saloga Joachim , Wonigeit Kurt , Gelfand Erwin W. 
Published: March 2007

AbstractCD45RA+ cells have been described to be less responsive to CD3/T cell receptor (TcR)‐mediated activation than CD45R0+ T cells. To analyze the underlying mechanism of the differential responses we compared CD3/TcR‐triggered tyrosine phosphorylation in the two subsets and studied the role of co‐stimulatory signals provided either by accessory cells or pharmacologic activation of protein kinase C by phorbol ester. Stimulation of purified CD45RA+ and CD45R0+ T cells with CD3/TcR antibodies induced similar patterns and intensities of tyrosine phosphorylation in the two subsets, but no proliferation. If accessory cells were used as the source of co‐stimulatory signals, strong expression of the 55‐kDa chain of the interleukin‐2 (IL‐2) receptor (CD25), significant IL‐2 production and vigorous proliferation were observed in CD45R0+ cells, whereas CD45RA+ cells responded weakly. However, when CD3/TcR‐mediated triggering was combined with activation of protein kinase C by phorbol ester, CD45RA+ cells responded strongly. These data indicate that the transmembrane signaling capacity of the T cell receptor expressed by CD45RA+ and CD45R0+ cells is similar and, therefore, is presumably not responsible for the differential reactivities of the two subsets. It is more likely that co‐stimulatory signals determine whether CD3/TcR‐initiated activation results in strong or weak responses.
Interleukin‐13 alters the activation state of murine macrophages in vitro: Comparison with interleukin‐4 and interferon‐γ
Authors: Doyle Anthony G. , Herbein Georges , Montaner Luis J. , Minty Adrian J. , Caput Daniel , Ferrara Pascual , Gordon Siamon 
Published: March 2007

AbstractInterleukin (IL)‐13 is a newly described cytokine expressed by activated lymphocytes. We examined the effects of the murine recombinant cytokine on the phenotype and activation status of elicited peritoneal macrophages (Mϕ), concentrating on activities which are known to be modulated by interferon‐γ and IL‐4. IL‐13 markedly suppressed nitric oxide release and to a lesser extent secretion of the pro‐inflammatory cytokine tumor necrosis factor‐α. However, antimicrobial capacity was not completely jeopardized as the respiratory burst was unaffected, and indeed the enhanced expression of Mϕ mannose receptor and major histocompatibility class II, and regulation of sialoadhesin, the Mϕ sialic acid‐specific receptor involved in hemopoietic and lymphoid interactions, suggest that these cells are not simply deactivated, but primed for an active role in immune and inflammatory responses. These activities closely mimic those of IL‐4, but mediation of the effects by IL‐4 was discounted by the use of a neutralizing monoclonal antibody. Thus, IL‐13, like IL‐4, is a cytokine which has complex effects on Mϕ behavior, inducing activities characteristic of both activation and deactivation.
The 5′ boundary of somatic hypermutation in a Vχ gene is in the leader intron
Authors: Rada Cristina , González‐Fernández Africa , Jarvis John M. , Milstein César 
Published: March 2007

AbstractThe maturation of the immune response involves the hypermutation of antibody genes and the selection of B cells expressing receptors with improved antigen binding properties. Somatic hypermutation of antibody genes is targeted to a small region ∼1 kb surrounding the rearranged V gene. The precise definition of the 5′ limit is not yet clear since the data base of somatic mutations upstream of the V region is very restricted. The available data suggest that it lies close to the promoter region and this has been used to implicate transcription in the mechanism leading to hypermutation. Here we present an extensive analysis of mutations in the 5′ region of a single χ light chain gene. A large data base from highly mutated sequences was obtained from anti‐oxazolone hybridomas expressing the VχOx1‐Jχ5 light chain and from polymerase chain reaction‐derived clones from splenic and Peyer's patches of transgenic mice expressing the same VχOx1‐Jχ5 gene combination. Although mutations were found in the 5′‐flanking segment, the rate of mutation in the V‐J segment was about 20‐fold higher. A sharp decline between those two mutation rates is evident but the boundary was found in the leader intron of the VχOx1 gene, about 150 bases downstream of the initiation of transcription site.
Induction of a cytotoxic T cell response by co‐injection of a T helper peptide and a cytotoxic T lymphocyte peptide in incomplete Freund's adjuvant (IFA): Further enhancement by pre‐injection of IFA alone
Authors: Valmori Danila , Romero Jackeline F. , Men Ying , Maryanski Janet L. , Romero Pedro , Corradin Giampietro 
Published: March 2007

AbstractWe have previously demonstrated that it is possible to induce a consistent and strong cytolytic T lymphocyte (CTL) response to synthetic peptides, corresponding to poorly immunogenic malaria CTL epitopes, by co‐injecting them with peptides representing defined T helper (Th) epitopes in incomplete Freund's adjuvant (IFA). In this study we have tested different immunization protocols to improve further the elicitation of the CTL response. We show that the CTL response to a mixture of Th + CTL peptides administered in IFA was further enhanced by a previous injection of the Th epitope peptide in IFA. Moreover, we found that the response could be significantly augmented by a pre‐injection of IFA alone. This enhancement was observed only if the Th epitope was also present in the second injection. The number of lymph node cells recovered was 2–3‐fold higher in mice pre‐injected with IFA, but the increase in specific CTL activity, expressed as lytic units per animal, by pre‐injection of IFA was at least 10–20‐fold. Thus, pre‐injection of IFA clearly increases the magnitude of a subsequent CTL response.
Epstein‐Barr virus (EBV) latent membrane protein 1 increases HLA class II expression in an EBV‐negative B cell line
Authors: Zhang Qin , Brooks Louise , Busson Pierre , Wang Fred , Charron Dominique , Kieff Eliott , Rickinson Alan B. , Tursz Thomas 
Published: March 2007

AbstractTransformation of normal resting B cells by the Epstein‐Barr virus (EBV) leads to the establishment of permanent lymphoblastoid cell lines (LCL) which express high levels of HLA antigens and which are highly efficient in antigen presentation. Certain features of the LCL phenotype can be reproduced by transfecting EBV‐negative B lymphoma (BL) cell lines with individual EBV latent genes under heterologous promoters. In this work we have analyzed a series of subclones derived from the EBV‐negative cell line Louckes, stably transfected with constructs encoding EBV latent genes for their expression of HLA class II molecules. Louckes parental cells and control transfectants expressed detectable levels of HLA‐DR, DQ and DP antigens on the cellular surface by cytofluorometry, but these levels were significantly increased in transfectants expressing the virus‐coded latent membrane protein 1 (LMP‐1). Northern blotting for the individual α and β chain mRNA at each of the three HLA class II loci indicated correspondingly increased levels of HLA class II transcripts in the LMP‐1 transfectants. Transfectants expressing the virus‐coded nuclear antigens EBNA‐1, EBNA‐2 or EBNA‐LP showed no significant changes in these parameters. These observations indicate that up‐regulation of HLA‐class II molecules can be a part of the changes induced by LMP‐1 in B cells.
Induction of murine cytotoxic T lymphocytes against Plasmodium falciparum sporozoite surface protein 2
Authors: Wizel Benjamin , Rogers William O. , Houghten Richard A. , Lanar David E. , Tine John A. , Hoffman Stephen L. 
Published: March 2007

AbstractSporozoite surface protein 2 has been identified as a target of malaria vaccines designed to produce protective CD8+ cytotoxic T lymphocytes (CTL) because mice immunized with mastocytoma cells expressing a fragment of Plasmodium yoelii sporozoite surface protein 2 (PySSP2) are protected against malaria by an immune response that requires CD8+ CTL. To define CTL epitopes in the Plasmodium falciparum sporozoite surface protein 2 (PfSSP2), spleen cells (SC) from mice immunized with irradiated sporozoites (irr spz), were stimulated with synthetic peptides, and these effectors were tested for cytolytic activity against peptide‐pulsed, major histocompatibility complex (MHC)‐matched targets. Two peptides containing CTL epitopes, A6 (Pf SSP2 3D7 214–233) and BH1 (Pf SSP2 3D7 3–11) were identified in bulk cultures of SC from immune C57BL/6 mice, and by production of CTL lines. Immunization with recombinant vaccinia expressing the full length PfSSP2 induced antigen specific, MHC‐restricted, CD8+ T cell‐dependent cytolytic activity against these two peptides. Finally, CTL were induced by immunization with a bacteria‐derived recombinant fragment of PfSSP2 (rPfSSP2) mixed with a liposomal formulation containing a cationic lipid (Lipofectin® Reagent, LPF). Induced CTL lysed target cells pulsed with peptide A6 or with LPF/rPfSSP2, but not targets pulsed with only rPfSSP2. These studies demonstrate that CTL specific to PfSSP2 are present in C57BL/6 mice and that immunization with purified rPfSSP2 delivered with LPF induces a cytotoxic T cell response.
Inherited complement C3 deficiency: A defect in C3 secretion
Authors: Katz Yitzhak , Singer Lori , Wetsel Rick A. , Schlesinger Menachem , Fishelson Zvi 
Published: March 2007

AbstractThe molecular basis of inherited complement C3 deficiency in a 20‐year‐old newly diagnosed male patient was studied. Using an enzyme‐linked immunosorbent assay, the patient's C3 serum level was found to be approximately 7 μg/ml, which is less than 1 % of normal. In contrast, Northern analysis indicated that the patient's C3 mRNA was of normal size and quantity. Peripheral blood monocytes (PBM) and skin fibroblast cultures (F) from the patient and from healthy donors were labeled for 2 h with [35S] methionine. Analysis of cell lysates and supernatants by immunoprecipitation and sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE) demonstrated normal levels of C3 in lysates of patient's PBM and F. However, C3 secretion in the patient's cells was extremely reduced, with pulse‐chase experiments demonstrating a long delay in the disappearance of intracellular C3. Secretion of C1r and factor B by the patient's cells was normal. Lipopolysaccharide and interleukin‐1 increased C3 synthesis in the patient's PBM and F, but had no effect on the secretion. SDS‐PAGE analysis of trypsin‐cleaved intracellular C3 revealed an aberrant cleavage profile for the patient's C3. Collectively, these data indicate that C3 deficiency in this patient is due to a defect in the C3 secretion, probably as the result of abnormality in the proC3 structure.