bluuebunny/crossref_metadata_2025_split huggingface dataset:
Human Vascular Endothelial Cells Favor Clonal Expansion of Unusual Alloreactive CTL
Authors: Biedermann Barbara C. , Pober Jordan S. 
Published: December 2022

AbstractWe have shown previously that cultured HUVEC or mixtures of endothelial cells (EC) and B lymphoblastoid cells (BLC) induce the differentiation of purified CD8+ PBL into allospecific, class I MHC-restricted CTL that lyse EC, but not BLC autologous to EC. Furthermore, these EC-selective CTL lines secrete little IFN-γ after target cell contact. In the present study, we have analyzed these polyclonal populations at a single cell level by cloning at limiting dilution and propagating the resulting CTL clones in the absence of EC. Phenotypically stable, alloreactive EC-selective CTL preferentially emerge from cocultures in which EC or EC + BLC are the initial stimulating cell types compared with cocultures stimulated by BLC alone (p = 0.005). Compared with BLC-stimulated CTL, EC-stimulated CTL clones often fail to secrete IFN-γ after target cell contact (p = 0.0006) and constitutively express CD40 ligand (CD40L) at rest (p = 0.0006). The absence of IFN-γ secretion does not result from a switch to IL-4 secretion. The expression of CD40L inversely correlates with the secretion of IFN-γ after target cell contact (p = 0.0001), but correlations of CD40L expression and failure to secrete IFN-γ with EC-selective killing did not reach statistical significance. We conclude that in a microenvironment in which allogeneic EC are in close contact with infiltrating CD8+ T cells, such as within a graft arterial intima, CTL subsets may emerge that display EC selectivity or express CD40L and secrete little IFN-γ after Ag contact.
Reactive Oxygen Intermediates Enhance Fcγ Receptor Signaling and Amplify Phagocytic Capacity
Authors: Pricop Luminita , Gokhale Jayashree , Redecha Patricia , Ng Sonia C. , Salmon Jane E. 
Published: December 2022

AbstractReceptors for the Fc region of IgG (FcγR) mediate internalization of opsonized particles by human neutrophils (PMN) and mononuclear phagocytes. Cross-linking of FcγR leads to activation of protein tyrosine kinases and phosphorylation of immunoreceptor tyrosine-based activation motifs (ITAMs) within FcγR subunits, both obligatory early signals for phagocytosis. Human PMN constitutively express two structurally distinct FcγR, FcγRIIa and FcγRIIIb, and can be induced to express FcγRI by IFN-γ. We have previously shown that stimulation of PMN through FcγRIIIb results in enhanced FcγRIIa-mediated phagocytic activity that is inhibited by catalase. In the present study, we have tested the hypothesis that reactive oxygen intermediates (ROI) have the capacity to regulate FcγR responses and defined a mechanism for this effect. We show that H2O2 augmented phagocytosis mediated by FcγRIIa and FcγRI in PMN and amplified receptor-triggered tyrosine phosphorylation of FcγR-associated ITAMs and signaling elements. Generation of endogenous oxidants in PMN by cross-linking FcγRIIIb similarly enhanced phosphorylation of FcγRIIa and Syk, a tyrosine kinase required for phagocytic function, in a catalase-sensitive manner. Our results provide a mechanism for priming phagocytes for enhanced responses to receptor-driven effects. ROI generated in an inflammatory milieu may stimulate quiescent cells to rapidly increase the magnitude of their effector function. Indeed, human monocytes incubated in the presence of stimulated PMN showed oxidant-induced increases in FcγRIIa-mediated phagocytosis. Definition of the role of oxidants as amplifiers of FcγR signaling identifies a target for therapeutic intervention in immune complex-mediated tissue injury.
IFN-γ Exposes a Cryptic Cytotoxic T Lymphocyte Epitope in HIV-1 Reverse Transcriptase
Authors: Sewell Andrew K. , Price David A. , Teisserenc Helene , Booth Bruce L. , Gileadi Uzi , Flavin Fiona M. , Trowsdale John , Phillips Rodney E. , Cerundolo Vincenzo 
Published: December 2022

AbstractThe proteasome, an essential component of the ATP-dependent proteolytic pathway in eukaryotic cells, is responsible for the degradation of most cellular proteins and is believed to be the main source of MHC class I-restricted antigenic peptides for presentation to CTL. Inhibition of the proteasome by lactacystin or various peptide aldehydes can result in defective Ag presentation, and the pivotal role of the proteasome in Ag processing has become generally accepted. However, recent reports have challenged this observation. Here we examine the processing requirements of two HLA A*0201-restricted epitopes from HIV-1 reverse transcriptase and find that they are produced by different degradation pathways. Presentation of the C-terminal ILKEPVHGV epitope is impaired in ME275 melanoma cells by treatment with lactacystin, and is independent of expression of the IFN-γ-inducible proteasome β subunits LMP2 and LMP7. In contrast, both lactacystin treatment and expression of LMP7 induce the presentation of the N-terminal VIYQYMDDL epitope. Consistent with these observations we show that up-regulation of LMP7 by IFN-γ enhances presentation of the VIYQYMDDL epitope. Hence interplay between constitutive and IFN-γ-inducible β-subunits of the proteasome can qualitatively influence Ag presentation. These observations may have relevance to the patterns of immunodominance during the natural course of viral infection.
Human Virus-Specific CD8+ CTL Clones Revert from CD45ROhigh to CD45RAhigh In Vivo: CD45RAhighCD8+ T Cells Comprise Both Naive and Memory Cells
Authors: Wills Mark R. , Carmichael Andrew J. , Weekes Michael P. , Mynard Kim , Okecha Georgina , Hicks Ray , Sissons J. G. Patrick 
Published: December 2022

AbstractIt has been generally believed that human CD8+ memory cells are principally found within the CD45ROhigh population. There are high frequencies of CD8+ memory CTL specific for the human CMV tegument phosphoprotein pp65 in PBMC of long-term virus carriers; the large population of memory CTL specific for a given pp65 peptide contains individual CTL clones that have greatly expanded. In this study, we found high frequencies of pp65 peptide-specific memory CTL precursors in the CD45ROhighCD45RA− population, but also appreciable frequencies in the CD45RAhigh subpopulation. Because the majority of CD8+ T cells in PBMC are CD45RAhigh, more of the total pp65-specific memory CTL pool is within the CD45RAhigh than in the CD45ROhigh compartment. Using clonotypic oligonucleotide probes to quantify the size of individual pp65-specific CTL clones in vivo, we found the CD45RAhigh population contributed 6- to 10-fold more than the CD45ROhigh population to the total virus-specific clone size in CD8+ cells. During primary CMV infection, an individual virus-specific CTL clone was initially CD45ROhigh, but after resolution of infection this clone was detected in both the CD45ROhigh and the CD45RAhigh populations. We conclude that CD45RA+ human CD8+ T cells do not solely comprise naive cells, but contain a very significant proportion of memory cells, which can revert from the CD45ROhigh to CD45RAhigh phenotype in vivo.
Therapeutic Protective Effects of IL-12 Combined with Soluble IL-4 Receptor Against Established Infections of Herpes Simplex Virus Type 1 in Thermally Injured Mice
Authors: Kobayashi Hiroyuki , Kobayashi Makiko , Utsunomiya Tokuichiro , Herndon David N. , Pollard Richard B. , Suzuki Fujio 
Published: December 2022

AbstractThe effect of combination therapy between IL-12 and soluble IL-4R (sIL-4R) on the established infection of HSV-1 in thermally injured mice (TI mice) was investigated. All of the TI mice infected with lethal amounts of HSV-1 died when IL-12 was given therapeutically at a dose of 500 U/mouse. However, 80% of these mice treated prophylactically with IL-12 survived compared with 0% survival of the same mice treated with saline. The therapeutic administration of IL-12 to TI mice currently infected with HSV-1 caused an 80% survival of these mice when the treatment was combined with sIL-4R. Although IL-12 did not stimulate IFN-γ production in cultures of splenic T cells from TI mice, IFN-γ was produced by stimulation with IL-12 when the producer cells were prepared from TI mice that had been treated previously with sIL-4R. After stimulation with anti-CD3 mAb, splenic T cells from TI mice with the established infection of HSV-1 produced IL-4 into their culture fluids. However, IL-4 was not produced by splenic T cells that were prepared from the same infected mice treated with IL-12 and sIL-4R in combination. The results obtained herein indicate that the efficacies of the combination therapy against the established infection of HSV-1 may result from the IFN-γ production stimulated by IL-12 in TI mice that are treated with sIL-4R for reducing burn-associated type 2 T cell responses.
The Promoter of the C1 Inhibitor Gene Contains a Polypurine·Polypyrimidine Segment that Enhances Transcriptional Activity
Authors: Zahedi Kamyar , Bissler John J. , Prada Anne E. , Prada Jorge A. , Davis Alvin E. 
Published: December 2022

AbstractThe C1 inhibitor (C1INH) promoter is unusual in two respects: 1) It contains no TATA sequence, but instead contains a TdT-like initiator element (Inr) at nucleotides −3 to +5; 2) it contains a polypurine·polypyrimidine tract between nucleotides −17 and −45. Disruption of the Inr by the introduction of point mutations reduced promoter activity by 40%. A TATA element inserted at nucleotide −30 in the wild-type promoter and in promoter constructs containing the mutated Inr led to a 2-fold increase in basal promoter activity. Previous studies suggested that the potential hinged DNA-forming polypurine·polypyrimidine tract might be important in the regulation of C1INH promoter activity. The present studies indicate that this region is capable of such intramolecular triple helix formation. Disruption of the polypurine·polypyrimidine sequence by substitution of 5 of the 23 cytosine residues with adenine prevented triple helix formation. Site-directed mutagenesis experiments demonstrate that the regulation of promoter activity is independent of hinged DNA-forming capacity but requires an intact AC box (ACCCTNNNNNACCCT) or the overlapping PuF binding site (GGGTGGG). The C1INH gene also contains a number of potential regulatory elements, including an Sp-1 and an hepatocyte nuclear factor-1 binding site and a CAAT box. The role of these elements in regulation of the C1INH promoter was examined. Elimination of the hepatocyte nuclear factor-1 site at nucleotides −94 to −81 by truncation reduced the activity of the promoter by ∼50%. Similarly, site-directed mutations that disrupt this site reduce promoter activity by 70%.
Recognition of Class I MHC by NK Receptor Ly-49C: Identification of Critical Residues
Authors: Lian Rebecca H. , Li Yan , Kubota Satoko , Mager Dixie L. , Takei Fumio 
Published: December 2022

AbstractThe Ly-49 family of inhibitory receptors plays a major role in regulating mouse NK cell cytotoxicity. Two of its members, Ly-49C and I, are recognized by the mAb 5E6, which also defines a subset of NK cells involved in the hybrid resistance phenomenon. Previous studies have shown that Ly-49C binds to a broad spectrum of class I MHC molecules, while Ly-49I apparently does not bind to any class I MHC molecules tested. In the present investigation we have defined the amino acid residues of Ly-49C that are critical for determining its ligand specificities. First, using quantitative COS cell adhesion assays, we demonstrated that Ly-49CB6 bound to Dd, Db, Kb, or Kk as well as to murine leukemic cell lines GM979 (H-2s) and IC-21 (H-2b). In contrast, COS cells expressing Ly-49IB6 did not significantly bind to any of the class I MHC tested. To determine which amino acid residues of Ly-49C are critical for their specific binding to class I MHC, a series of chimeric and mutant Ly-49C and I were generated and tested. Exchanging the critical residues between Ly-49C and I significantly affected their binding specificities. Finally, we identified the epitopes on Ly-49C recognized by mAbs 5E6 and 4LO3311 that functionally inhibit Ly-49C recognition of its ligands. These results further define the class I specificities of Ly-49C and provide insight into the structural basis for how class I MHC is recognized by the Ly-49 family of NK receptors.
The Th1/Th2 Balance Does Not Account for the Difference of Susceptibility of Mouse Strains to Theiler’s Virus Persistent Infection
Authors: Monteyne Philippe , Bihl Franck , Levillayer Florence , Brahic Michel , Bureau Jean-François 
Published: December 2022

AbstractTheiler’s virus causes a persistent infection with demyelination that is studied as a model for multiple sclerosis. Inbred strains of mice differ in their susceptibility to viral persistence due to both H-2 and non-H-2 genes. A locus with a major effect on persistence has been mapped on chromosome 10, close to the Ifng locus, using a cross between susceptible SJL/J and resistant B10.S mice. We now confirm the existence of this locus using two lines of congenic mice bearing the B10.S Ifng locus on an SJL/J background, and we describe a deletion in the promoter of the Ifng gene of the SJL/J mouse. We studied the expression of IFN-γ, IL-2, IL-10, and IL-12 in the brains of SJL/J mice, B10.S mice, and the two lines of congenic mice during the first 2 wk following inoculation. We found a greater expression of IFN-γ and IL-2 mRNA in the brains of B10.S mice compared with those of SJL/J mice. Also, the ratio of IL-12 to IL-10 mRNA levels was higher in B10.S mice. However, the cytokine profiles were the same for the two lines of resistant congenic mice and for susceptible SJL/J mice. Therefore, the difference of Th1/Th2 balance between the B10.S and SJL/J mice is not due to the Ifng locus and does not account for the difference of susceptibility of these mice to persistent infection.
Antibody Prevents Virus Reactivation Within the Central Nervous System
Authors: Lin Mark T. , Hinton David R. , Marten Norman W. , Bergmann Cornelia C. , Stohlman Stephen A. 
Published: December 2022

AbstractThe neurotropic JHM strain of mouse hepatitis virus (JHMV) produces an acute CNS infection characterized by encephalomyelitis and demyelination. The immune response cannot completely eliminate virus, resulting in persistence associated with chronic ongoing CNS demyelination. The contribution of humoral immunity to viral clearance and persistent infection was investigated in mice homozygous for disruption of the Ig μ gene (IgM−/−). Acute disease developed with equal kinetics and severity in IgM−/− and syngeneic C57BL/6 (wt) mice. However, clinical disease progressed in IgM−/− mice, while wt mice recovered. Viral clearance during acute infection was similar in both groups, supporting a primary role of cell-mediated immunity in viral clearance. In contrast to wt mice, in which infectious virus was reduced to below detection following acute infection, increasing infectious virus was recovered from the CNS of the IgM−/− mice following initial clearance. No evidence was obtained for selection of variant viruses nor was there an apparent loss of cell-mediated immunity in the absence of Ab. Passive transfer of anti-JHMV Ab following initial clearance prevented reactivation of infectious virus within the CNS of IgM−/− mice. These data demonstrate the clearance of infectious virus during acute disease by cell-mediated immunity. However, immunologic control is not maintained in the absence of anti-viral Ab, resulting in recrudescence of infectious virus. These data suggest that humoral immunity plays no role in controlling virus during acute infection, but plays an important role in establishing and maintaining CNS viral persistence.
Antiproliferative Effect of IL-1 Is Mediated by p38 Mitogen-Activated Protein Kinase in Human Melanoma Cell A375
Authors: Itoh Saotomo , Hattori Takayuki , Hayashi Hidetoshi , Mizutani Yukiko , Todo Makoto , Takii Takemasa , Yang De , Lee John C. , Matsufuji Senya , Murakami Yasuko , Chiba Taku , Onozaki Kikuo 
Published: December 2022

AbstractThe role of p38 mitogen-activated protein kinase (MAPK) in IL-1-induced growth inhibition was investigated using IL-1-sensitive human melanoma A375-C2-1 cells and IL-1-resistant A375-R8 cells. In both cells, p38 MAPK was activated by IL-1. A selective inhibitor for p38 MAPK, SB203580, almost completely recovered the IL-1-induced growth inhibition in A375-C2-1 cells. IL-1-induced IL-6 production was also suppressed by SB203580. However, the reversal effect of SB203580 was not due to the suppression of IL-6 production because the SB203580 effect was still observed in the presence of exogenous IL-6. Down-regulation of ornithine decarboxylase (ODC) activity as well as its protein level has been shown to be essential for IL-1-induced growth inhibition. SB203580 also reversed the IL-1-induced down-regulation of ODC activity and intracellular polyamine levels without affecting ODC mRNA levels in A375-C2-1 cells. In IL-1-resistant R8 cells, however, IL-1 only slightly suppressed ODC activity. In A375-C2-1 cells, the mRNA expression level of antizyme (AZ), a regulatory factor of ODC activity, has been shown to be up-regulated by IL-1. IL-1-induced up-regulation of AZ mRNA level was not affected by SB203580. These findings demonstrate that p38 MAPK plays an important role in IL-1-induced growth inhibition in A375 cells through down-regulating ODC activity without affecting the level of ODC mRNA and AZ mRNA. In IL-1-resistant A375-R8 cells, IL-1 signaling pathway is deficient between p38 MAPK activation and down-regulation of ODC activity.
Targeting of Human Dendritic Cells by Autologous NK Cells
Authors: Wilson Julia L. , Heffler Lena C. , Charo Jehad , Scheynius Annika , Bejarano Maria-Teresa , Ljunggren Hans-Gustaf 
Published: December 2022

AbstractNK cells have the capacity to spontaneously kill tumor cell lines, in particular cell lines of hemopoietic origin. In contrast, they do not generally kill nontransformed autologous cells. However, here we demonstrate that short-term activated polyclonal human NK cells, as well as human NK cell lines, efficiently lyse autologous dendritic cells (DC) derived from peripheral blood monocytes as well as Langerhans-like cells derived from CD34+ stem cells isolated from umbilical cord blood. Lysis of autologous DC by short-term activated NK cells and NK cell lines was dependent on granule exocytosis, since total abrogation of lysis was observed in the presence of EGTA. Induction of DC maturation by LPS, monocyte conditioned media (MCM), or stimulation through CD40 ligand (CD40L) rendered the DC less susceptible to lysis by NK cells. Infection of DC with influenza virus was likewise associated with a reduced susceptibility to lysis by NK cells. Thus, susceptibility to lysis by autologous NK cells is a particular property of immature DC. The present results are discussed in relation to the ability of DC to interact with NK cells and to the ability of NK cells to regulate development of specific immunity.
Follicular Dendritic Cells Protect Malignant B Cells from Apoptosis Induced by Anti-Fas and Antineoplastic Agents
Authors: Schwarz Ying X. , Yang Ming-yan , Qin Dahui , Wu Jiuhua , Jarvis W. David , Grant Steven , Burton Gregory F. , Szakal Andras K. , Tew John G. 
Published: December 2022

AbstractThe observation that follicular dendritic cells (FDC) reduce apoptosis in B cells prompted the hypothesis that FDC might enhance tumor cell survival by protecting malignant B cells from apoptotic death. To test this notion, apoptosis was induced in B cell lymphomas by anti-Fas or various antineoplastic agents in the presence and absence of FDC. Apoptosis was detected and quantified by TUNEL analysis. Induction of apoptosis with anti-Fas, etoposide, cyclophosphamide, and busulfan was markedly antagonized by FDC at FDC to B cell ratios of ≥1:16. For example, treatment with 10 ng/ml anti-Fas caused 60–90% of A20 cells to undergo apoptosis in 6 h, whereas addition of FDC reduced apoptosis to background levels (3–15%). Similarly, treatment with busulfan induced apoptosis in 55–80% of A20 cells, whereas addition of FDC reduced B cell death to ≤15%; moreover, depletion of FDC abrogated the protective actions. In contrast, the apoptosis-inducing effect of Adriamycin was not reversed by FDC. The ability to block apoptosis induced by anti-Fas or busulfan was not limited to A20 but was observed in four other malignant pre-B cell or B cell lines. The mechanism by which FDC spare malignant B cells from apoptosis did not involve alterations in levels of Bcl-2, Bcl-XL, or Bax. Collectively, these data raise the possibility that FDC may enhance tumor cell survival by protecting malignant B cells against apoptosis induced by anti-Fas and some but not all chemotherapeutic agents.
Ability of a Nondepleting Anti-CD4 Antibody to Inhibit Th2 Responses and Allergic Lung Inflammation Is Independent of Coreceptor Function
Authors: Li Li , Crowley Mary , Nguyen Andrea , Lo David 
Published: December 2022

AbstractNondepleting anti-CD4 Abs have been used in vivo to induce Ag-specific immunological tolerance in Th1 responses, including tissue allograft rejection and autoimmune diabetes. To examine whether this Ab (YTS177.9) acts by provoking a Th2 shift, we tested the effect in a mouse model of allergic lung inflammation. Interestingly, nondepleting anti-CD4 treatment induces tolerance to allergens as well, especially when given during initial priming. In vitro studies indicate that the effect of the Ab is independent of CD4 coreceptor function, as Ab treatment also inhibits proliferation and induces a persistent anergy in naive CD4 T cells stimulated by anti-CD3/CD28. Moreover, the Ab stimulated a distinct pattern of tyrosine phosphorylation in T cells even in the absence of TCR triggering, suggesting that signaling through CD4 alone induces significant physiological changes in T cell function. These results show that tolerance induced by anti-CD4 triggering is not a simple shift in Th1/Th2 effector function or depletion of Ag-specific cells, but may instead induce a persistent clonal anergy capable of blocking subsequent immunity.
Selective Pharmacologic Inhibition of Murine and Human IL-12-Dependent Th1 Differentiation and IL-12 Signaling
Authors: Coon Michael E. , Diegel Michael , Leshinsky Natasha , Klaus Stephen J. 
Published: December 2022

AbstractWe have previously shown that lisofylline (LSF) inhibits murine Th1-mediated disease in vivo by blocking IL-12-induced differentiation of Th1 cells. The cellular and molecular mechanisms underlying this inhibition were further explored by testing LSF in several IL-12-responsive model systems in vitro. IL-12-dependent Th1 differentiation was abrogated by LSF and yielded effector T cells that were deficient in proinflammatory cytokine secretion, including IFN-γ, IL-2, and TNF-α. The diminished Th1 phenotype resulted from both a lower frequency of IL-12-derived Th1 clones and a reduced capacity of individual clones to secrete IFN-γ due to lower levels of IFN-γ mRNA. The arrest in Th1 development resulted from a blockade of IL-12 signaling that preceded the Th0 to Th1 transition. Thus, LSF blocked IL-12-enhanced IFN-γ production in anti-CD3-stimulated T cells and prevented IL-12-mediated repression of the transcription factor GATA-3. Lisofylline also inhibited IL-12-induced increases in STAT4 tyrosine phosphorylation, but did not block TCR signaling or inhibit acquisition of IL-12 responsiveness. These findings were extended to show that LSF also inhibits IL-12-dependent responses in human T cells. LSF, which has one asymmetric chiral center, was selectively inhibitory for IL-12 signaling compared with its S-enantiomer (1501-S) and the oxidized side chain analog, pentoxifylline. The results suggest that LSF may be useful as a modulator of Th1-mediated disease in humans.