bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thymic Stromal Lymphopoietin: A Cytokine That Promotes the Development of IgM+ B Cells In Vitro and Signals Via a Novel Mechanism
Authors: Levin Steven D. , Koelling Ray M. , Friend Sherree L. , Isaksen Deborah E. , Ziegler Steven F. , Perlmutter Roger M. , Farr Andrew G. 
Published: December 2022

AbstractA novel cytokine from a thymic stromal cell line (thymic stromal lymphopoietin (TSLP)) promotes the development of B220+/IgM+ immature B cells when added to fetal liver cultures, long term bone marrow cultures, or bone marrow cells plated in semisolid medium. Because the activities of TSLP overlap with those of IL-7 in some in vitro assays, we compared the signaling mechanisms employed by TSLP and IL-7. Proliferation of a factor-dependent pre-B cell line (NAG8/7) in response to either TSLP or IL-7 was inhibited by anti-IL-7Rα mAbs, suggesting that the functional TSLP receptor complex uses IL-7Rα. In contrast, three different Abs to the common cytokine receptor γ-chain had no effect on the response of these cells to TSLP, indicating that the functional TSLP receptor complex does not use the common cytokine receptor γ-chain. Both cytokines induced activation of Stat5, but only IL-7 induced activation of the Janus family kinases Jak1 and Jak3. In fact, TSLP failed to activate any of the four known Janus family kinases, suggesting that Stat5 phosphorylation is mediated by a novel mechanism. Taken together, these data support the idea that TSLP can make unique contributions to B lymphopoiesis and indicate that it does so by mechanisms distinct from IL-7.
T Cell Responses to Heat-Shock Protein 60: Differential Responses by CD4+ T Cell Subsets According to Their Expression of CD45 Isotypes
Authors: Ramage Judith M. , Young Joyce L. , Goodall Jane C. , Hill Gaston J. S. 
Published: December 2022

AbstractWe demonstrate that human T lymphocytes proliferate in vitro to highly purified human heat-shock protein 60 (Hu.hsp60). The response to this self Ag was confined to the CD45RA+RO− T cell subset, with minimal responses by adult CD45RA−RO+ T cells. Experiments using keyhole limpet hemocyanin as a prototypic novel Ag, or tetanus toxoid as a recall Ag, were consistent with the notion that CD45RA+RO− and CD45RA−RO+ T cell subsets can be designated as naive and memory cells, respectively; thus, responses to Hu.hsp60 were confined to the putative naive subset. In contrast, both CD45RA+RO− and CD45RA−RO+ T cell populations proliferated to bacterial hsp60 from Mycobacterium leprae, Escherichia coli, or Chlamydia trachomatis. However, only CD45RA−RO+ (memory) T cells responded to a mycobacterial hsp60-derived peptide previously defined as a major bacteria-specific epitope. Experiments with cord blood T cells, which are CD45RA+RO− and can be considered truly naive, showed that the peptide could elicit responses from naive T cells in vitro; cord blood cells also responded to Hu.hsp60. Since bacterial hsp60 Ags contain both conserved and nonconserved epitopes, we speculate that in vivo challenge with bacterial hsp60 will activate T cells capable of seeing either type of epitope, but only those that see nonconserved epitopes maintain the CD45RA−RO+ memory phenotype. However, T cells recognizing conserved epitopes, while not apparently being recruited to the memory pool, may nevertheless play a role in immunoregulation, particularly in the context of inflammation, when expression of Hu.hsp60 is increased.
RT1-U: Identification of a Novel, Active, Class Ib Alloantigen of the Rat MHC
Authors: Leong Louise Y. W. , Le Rolle Anne-France , Deverson Edward V. , Powis Simon J. , Larkins Audrey P. , Vaage John T. , Stokland Aasa , Lambracht-Washington Doris , Rolstad Bent , Joly Etienne , Butcher Geoffrey W. 
Published: December 2022

Abstract
In common with other mammalian species, the laboratory rat (Rattus norvegicus) expresses MHC class I molecules that have been categorized as either classical (class Ia) or nonclassical (class Ib). This distinction separates the class Ia molecules that play a conventional role in peptide Ag presentation to CD8 T cells from the others, whose function is unconventional or undefined. The class Ia molecules are encoded by the RT1-A region of the rat MHC, while the RT1-C/E/M region encodes up to 60 other class I genes or gene fragments, a number of which are known to be expressed (or to be expressible). Here we report upon novel MHC class Ib genes of the rat that we have expression cloned using new monoclonal alloantibodies and which we term RT1-U. The products detected by these Abs were readily identifiable by two-dimensional analysis of immunoprecipitates and were shown to be distinct from the class Ia products. Cellular studies of these molecules indicate that they function efficiently as targets for cytotoxic killing by appropriately raised polyclonal alloreactive CTL populations. The sequences of these class Ib genes group together in phylogenetic analysis, suggesting a unique locus or family. The combined serological, CTL, and sequence data all indicate that these products are genetically polymorphic.
Evidence That an OX-2-Positive Cell Can Inhibit the Stimulation of Type 1 Cytokine Production by Bone Marrow-Derived B7-1 (and B7-2)-Positive Dendritic Cells
Authors: Gorczynski Laura , Chen Z. , Hu J. , Kai Y. , Lei J. , Ramakrishna V. , Gorczynski R. M. 
Published: December 2022

AbstractWe reported that hepatic mononuclear, nonparenchymal cells (NPC) can inhibit the immune response seen when allogeneic C57BL/6 dendritic cells (DC) are incubated with C3H spleen responder cells. Cells derived from these cultures transfer increased survival of C57BL/6 renal allografts in C3H mice. We also found that increased expression of OX-2 on DC was associated with inhibition of cytokine production and renal allograft rejection. We explored whether inhibition by hepatic NPC was a function of OX-2 expression by these cells. Fresh C57BL/6 spleen-derived DC were cultured with C3H spleen responder cells and other putative coregulatory cells. The latter were derived from fresh C3H or C57BL/6 liver NPC, or from C3H or C57BL/6 mice treated for 10 days by i.v. infusion of human Flt3 ligand. Different populations of murine bone marrow-derived DC from cultures of bone marrow with IL-4 plus granulocyte-macrophage-CSF were also used as a source of putative regulator cells. Supernatants of all stimulated cultures were examined for functional expression of different cytokines (IL-2, IL-4, IFN-γ, and TGFβ). We found that fresh C57BL/6 splenic DC induced IL-2, not IL-4, production. Cells from the sources indicated inhibited IL-2 and IFN-γ production and promoted IL-4 and TGFβ production. Inhibition was associated with increased expression of OX-2 on these cells, as defined by semiquantitative PCR and FACS analysis. By size fractionation, cells expressing OX-2 were a subpopulation of NLDC145+ cells. Our data imply a role for cells expressing OX-2 in the regulation of induction of cytokine production by conventional allostimulatory DC.
Orientation of the Ig Domains of CD8αβ Relative to MHC Class I
Authors: Devine Lesley , Sun Jiaren , Barr Mark R. , Kavathas Paula B. 
Published: December 2022

AbstractThe cell surface glycoprotein CD8 functions as a coreceptor with the TCR for interaction with MHC class I. The cocrystal structure of the CD8αα-MHC complex showed that one CD8 Ig domain provided the majority of the contact with MHC class I and that residue R4 of that domain contacted the α2 domain of MHC class I. We previously showed by mutational analysis that this residue was critical for binding to MHC class I. To determine which of the Ig domains for the CD8αβ heterodimer would make the most contact with class I MHC, we expressed single-chain or dimeric forms of CD8 on COS-7 cells and measured the adhesion of MHC class I positive cells. We found that when one of the R4 residues was mutated in a CD8αα homodimer binding comparable to that of wild type was observed, whereas a double R4 mutant severely impaired binding. However, when mutant CD8α (R4K) was coexpressed with wild-type CD8β, binding was not observed. These results support the model in which it is CD8α, not CD8β, that is making the most of the contact with MHC class I, including the α2 domain. In addition, they demonstrate that a single-chain form of CD8αα can bind to MHC class I.
Perforin-Deficient CD8+ T Cells: In Vivo Priming and Antigen-Specific Immunity AgainstListeria monocytogenes
Authors: White Douglas W. , MacNeil Adam , Busch Dirk H. , Pilip Ingrid M. , Pamer Eric G. , Harty John T. 
Published: December 2022

AbstractCD8+ T cells require perforin to mediate immunity against some, but not all, intracellular pathogens. Previous studies with H-2b MHC perforin gene knockout (PO) mice revealed both perforin-dependent and perforin-independent pathways of CD8+ T cell-mediated immunity to Listeria monocytogenes (LM). In this study, we address two previously unresolved issues regarding the requirement for perforin in antilisterial immunity: 1) Is CD8+ T cell-mediated, perforin-independent immunity specific for a single Ag or generalizable to multiple Ags? 2) Is there a deficiency in the priming of the CD8+ T cell compartment of PO mice following an immunizing challenge with LM? We used H-2d MHC PO mice to generate CD8+ T cell lines individually specific for three known Ags expressed by a recombinant strain of virulent LM. Adoptive transfer experiments into BALB/c host mice revealed that immunity can be mediated by PO CD8+ T cells specific for all Ags examined, indicating that perforin-independent immunity is not limited to CD8+ T cells that recognize listeriolysin O. Analysis of epitope-specific CD8+ T cell expansion by MHC class I tetramer staining and ELISPOT revealed no deficiency in either the primary or secondary response to LM infection in PO mice. These results demonstrate that the perforin-independent pathway of antilisterial resistance mediated by CD8+ T cells is generalizable to multiple epitopes. Furthermore, the results show that reduced antilisterial resistance observed with polyclonal PO CD8+ T cells is a consequence of a deficiency in effector function and not a result of suboptimal CD8+ T cell priming.
High Avidity CTLs for Two Self-Antigens Demonstrate Superior In Vitro and In Vivo Antitumor Efficacy
Authors: Zeh Herbert J. , Perry-Lalley Donna , Dudley Mark E. , Rosenberg Steven A. , Yang James C. 
Published: December 2022

Abstract
A majority of the human tumor-associated Ags characterized to date are derived from nonmutated “self”-proteins. Little is currently understood about the nature of the self-reactive lymphocytes that recognize these Ags. We recently characterized two nonmutated tumor-associated Ags for the B16 murine melanoma: tyrosinase-related protein-2 (TRP-2) and the endogenous retroviral envelope protein, p15E. We previously reported that both TRP-2 and p15E reactive CTL could be detected in the spleens of naive animals after a single in vitro stimulation using 10−5–10−6 M of the appropriate Kb-binding 9-amino acid epitope. In this report we show that the CTL found in naive animals are low avidity lymphocytes, that respond only to high concentrations of peptide in vitro. We demonstrate that titration of in vitro-stimulating peptide to limiting concentrations distinguishes qualitative differences in the lymphocyte reactivity to these two Ags between vaccinated and unvaccinated animals. We further demonstrate that in vitro expansion of CTL in either high or low concentrations of stimulating peptide generated CTL cultures with different avidities for the relevant epitopes. CTL expanded in low concentrations demonstrated higher avidity for peptide-pulsed targets and better tumor recognition, when compared to CTL generated in the presence of high concentrations of Ag. More importantly, high avidity CTL demonstrated superior in vivo antitumor activity. These results demonstrate that qualitative differences in the CTL that recognize these two self-Ags are critically important to their in vitro and in vivo anti-tumor efficacy.
Cutting Edge: Dominant Effect of Ile50Val Variant of the Human IL-4 Receptor α-Chain in IgE Synthesis
Authors: Mitsuyasu Hiromichi , Yanagihara Yukiyoshi , Mao Xiao-Quan , Gao Pei-Sun , Arinobu Yojiro , Ihara Kenji , Takabayashi Akira , Hara Toshiro , Enomoto Tadao , Sasaki Sei , Kawai Minoru , Hamasaki Naotaka , Shirakawa Taro , Hopkin Julian M. , Izuhara Kenji 
Published: December 2022

Abstract
Two variants of the IL-4R α-chain (IL-4Rα) gene have been recently identified in association with different atopic disorders. To clarify the etiological relationship between the two variants, we analyzed responsiveness to IL-4 of transfectants with four kinds of IL-4Rα carrying either Val or Ile at 50 and either Gln or Arg at 551. The substitution of Ile for Val augmented STAT6 activation, proliferation, and transcription activity of the Iε promoter by IL-4, whereas that of Arg for Gln did not change these IL-4 signals. Arg551 was not associated with atopic asthma in the Japanese population. CD23 expression and IgE synthesis by IL-4 were augmented in Ile50-bearing PBMC, compared with those bearing Val50. Taken together, substitution of Arg551 does not enhance the IL-4 signal for generation of germline ε transcript, whereas the substitution of Ile50 contributes to enhancement of IgE synthesis.
Regulation of Cytotoxic T Lymphocyte-Associated Molecule-4 by Src Kinases
Authors: Chuang Ellen , Lee Kyung-Mi , Robbins Michael D. , Duerr James M. , Alegre Maria-Luisa , Hambor John E. , Neveu Mark J. , Bluestone Jeffrey A. , Thompson Craig B. 
Published: December 2022

Abstract
Cytotoxic T lymphocyte-associated molecule-4 (CTLA-4) is a cell surface receptor expressed on activated T cells that can inhibit T cell responses induced by activation of the TCR and CD28. Studies with phosphorylated peptides based on the CTLA-4 intracellular domain have suggested that tyrosine phosphorylation of CTLA-4 may regulate its interactions with cytoplasmic proteins that could determine its intracellular trafficking and/or signal transduction. However, the kinase(s) that phosphorylate CTLA-4 remain uncharacterized. In this report, we show that CTLA-4 can associate with the Src kinases Fyn and Lck and that transfection of Fyn or Lck, but not the unrelated kinase ZAP70, can induce tyrosine phosphorylation of CTLA-4 on residues Y201 and Y218. A similar pattern of tyrosine phosphorylation was found in pervanadate-treated Jurkat T cells stably expressing CTLA-4. Phosphorylation of CTLA-4 Y201 in Jurkat cells correlated with cell surface accumulation of CTLA-4. CTLA-4 phosphorylation induced the association of CTLA-4 with the tyrosine phosphatase SHP-2, but not with phosphatidylinositol 3-kinase. In contrast, Lck-induced phosphorylation of CD28 resulted in the recruitment of phosphatidylinositol 3-kinase, but not SHP-2. These findings suggest that phosphorylation of CD28 and CTLA-4 by Lck activates distinct intracellular signaling pathways. The association of CTLA-4 with Src kinases and with SHP-2 results in the formation of a CTLA-4 complex with the potential to regulate T cell activation.
CD40-CD154 Interaction and IFN-γ Are Required for IL-12 But Not Prostaglandin E2 Secretion by Microglia During Antigen Presentation to Th1 Cells
Authors: Aloisi Francesca , Penna Giuseppe , Polazzi Elisabetta , Minghetti Luisa , Adorini Luciano 
Published: December 2022

AbstractIL-12 and PGE2 promote and inhibit, respectively, the development of Th1 responses. Production of these mediators by APC residing in the central nervous system (CNS) may be involved in the local regulation of the T cell phenotype during infectious and autoimmune CNS diseases. In the present study we have examined IL-12 and PGE2 secretion by cultured microglia and astrocytes from the mouse brain upon Ag-dependent interaction with I-Ad-restricted, OVA323–339 specific TCR transgenic Th1 and Th2 cell lines. We show that microglia, which restimulate efficiently both Th1 and Th2 cells, secrete IL-12 upon Ag-dependent interaction with Th1, but not with Th2 cells. Th1-driven IL-12 production depends on TCR ligation by MHC class II/peptide complexes, CD40 engagement on microglia, and IFN-γ secretion by activated Th1 cells. Th1 and, to a lesser extent, Th2 cells also stimulate the production of PGE2 by microglia. T cell-mediated induction of PGE2 requires MHC class II/peptide/TCR interactions but does not depend on CD40 engagement or on the presence of IFN-γ. Astrocytes, which preferentially activate Th2 cells, fail to produce IL-12 and secrete negligible amounts of PGE2 upon interaction with either Th1 or Th2 cells. These results suggest that during CNS infection or immunopathology, IL-12 produced by microglia upon Ag-specific interaction with Th1 cells may further skew the immune response to Th1, whereas the T cell-dependent production of PGE2 by microglia may represent a negative feedback mechanism, limiting the propagation of Th1 responses.
T Cell Epitopes of a Lipocalin Allergen Colocalize with the Conserved Regions of the Molecule
Authors: Zeiler Thomas , Mäntyjärvi Rauno , Rautiainen Jaakko , Rytkönen-Nissinen Marja , Vilja Pekka , Taivainen Antti , Kauppinen Juha , Virtanen Tuomas 
Published: December 2022

Abstract
In this study we characterized the human T cell-reactive sites of the major cow dander allergen, Bos d 2, a member of the lipocalin protein family. We showed that Bos d 2 contains only a limited number of epitopes. This is in contrast to many other allergens, which usually contain multiple T cell epitopes throughout the molecule. The epitopes of Bos d 2 were primarily concentrated in the conserved regions of the molecule. One of the epitopes was recognized by all the cow-asthmatic individuals regardless of their HLA phenotype. Computer-predicted T cell epitopes on Bos d 2, other lipocalin allergens, and human endogenous lipocalins were situated in similar locations on these molecules and corresponded to experimentally identified epitopes on Bos d 2. The results suggest that human endogenous lipocalins could be involved in the modulation of immune responses against exogenous lipocalin allergens. In addition, our findings are likely to facilitate the development of new forms of immunotherapy against allergies induced by the important group of lipocalin allergens.
Class II-Associated Invariant Chain Peptide-Independent Binding of Invariant Chain to Class II MHC molecules
Authors: Thayer Wesley P. , Ignatowicz Leszek , Weber Dominique A. , Jensen Peter E. 
Published: December 2022

AbstractThe class II-associated invariant chain peptide (CLIP) region of invariant chain (Ii) is believed to play a critical role in the assembly and transport of MHC class II αβIi complexes through its interaction with the class II peptide-binding site. The role of the CLIP sequence was investigated by using mutant Ii molecules with altered affinity for the DR1 peptide-binding site. Both high- and low-affinity mutants were observed to efficiently assemble with DR1 and mediate transport to endosomal compartments in COS cell transfectants. Using N- and C-terminal truncations, a region adjacent to CLIP within Ii(103–118) was identified that can complement loss of affinity for the peptide-binding site in mediating efficient assembly of αβIi. A C-terminal fragment completely lacking the CLIP region, Ii(103–216), was observed binding stably to class II molecules in immunoprecipitation studies and experiments with purified proteins. The Ii(103–118) region was required for this binding, which occurs through interactions outside of the αβ peptide-binding groove. We conclude that strong interactions involving Ii(103–118) and other regions of Ii cooperate in the assembly of functional αβIi under conditions where CLIP has little or no affinity for the class II peptide-binding site. Our results support the hypothesis that the CLIP sequence has evolved to avoid high-stability interactions with the peptide-binding sites of MHC class II molecules rather than as a promiscuous binder with moderate affinity for all class II molecules.
TFEC Is a Macrophage-Restricted Member of the Microphthalmia-TFE Subfamily of Basic Helix-Loop-Helix Leucine Zipper Transcription Factors
Authors: Rehli Michael , Lichanska Agnieszka , Cassady A. Ian , Ostrowski Michael C. , Hume David A. 
Published: December 2022

Abstract
The murine homologue of the TFEC was cloned as part of an analysis of the expression of the microphthalmia-TFE (MiT) subfamily of transcription factors in macrophages. TFEC, which most likely acts as a transcriptional repressor in heterodimers with other MiT family members, was identified in cells of the mononuclear phagocyte lineage, coexpressed with all other known MiT subfamily members (Mitf, TFE3, TFEB). Northern blot analysis of several different cell lineages indicated that the expression of murine TFEC (mTFEC) was restricted to macrophages. A 600-bp fragment of the TATA-less putative proximal promoter of TFEC shares features with many known macrophage-specific promoters and preferentially directs luciferase expression in the RAW264.7 macrophage cell line in transient transfection assays. Five of six putative Ets motifs identified in the TFEC promoter bind the macrophage-restricted transcription factor PU.1 under in vitro conditions and in transfected 3T3 fibroblasts; the minimal luciferase activity of the TFEC promoter could be induced by coexpression of PU.1 or the related transcription factor Ets-2. The functional importance of the tissue-restricted expression of TFEC and a possible role in macrophage-specific gene regulation require further investigation, but are likely to be linked to the role of the other MiT family members in this lineage.
Measles Virus Infection Synergizes with IL-4 in IgE Class Switching
Authors: Imani Farhad , Proud David , Griffin Diane E. 
Published: December 2022

AbstractIncreasing evidence suggests that viral infections are associated with the induction and exacerbation of asthma. One characteristic of human asthma is an increase in the levels of circulating IgE. Previous studies have shown that circulating IgE levels are elevated during the early phase of infection with measles virus (MV). We have shown previously that one mechanism by which viral infections can increase IgE levels is via an induction of IgE class switching through the activation of the antiviral protein kinase (dsRNA-activated protein kinase), leading to the activation of multiple NF-κB complexes. Therefore, to determine whether infection with MV can also induce IgE class switching, we infected the human Ramos B cell line with the Edmonston strain of MV. Infecting Ramos cells with MV did not result directly in either the activation of dsRNA-activated protein kinase or IgE class switching. However, a synergistic effect on IgE class switching was observed when Ramos cells were infected with MV before IL-4 treatment. Ab cross-linking of the MV receptor, CD46, mimicked the effects of MV infection in synergizing with IL-4 to induce IgE class switching, suggesting that viral hemagglutinin is involved in this synergistic effect. These data provide the first indication of a potential mechanism for MV-induced IgE up-regulation and suggest a model for a viral-induced exacerbation of IgE-mediated disorders such as asthma.