bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Dendritic Cell-Specific Adhesion Receptor DC-SIGN Internalizes Antigen for Presentation to T Cells
Authors: Engering Anneke , Geijtenbeek Teunis B. H. , van Vliet Sandra J. , Wijers Mietske , van Liempt Ellis , Demaurex Nicolas , Lanzavecchia Antonio , Fransen Jack , Figdor Carl G. , Piguet Vincent , van Kooyk Yvette 
Published: April 2014

Abstract
Dendritic cells (DCs) capture Ags or viruses in peripheral tissue to transport them to lymphoid organs to induce cellular T cell responses. Recently, a DC-specific C-type lectin was identified, DC-specific ICAM-grabbing non-integrin (DC-SIGN), that functions as cell adhesion receptor mediating both DC migration and T cell activation. DC-SIGN also functions as an HIV-1R that captures HIVgp120 and facilitates DC-induced HIV transmission of T cells. Internalization motifs in the cytoplasmic tail of DC-SIGN hint to a function of DC-SIGN as endocytic receptor. In this study we demonstrate that on DCs DC-SIGN is rapidly internalized upon binding of soluble ligand. Mutating a putative internalization motif in the cytoplasmic tail reduces ligand-induced internalization. Detailed analysis using ratio fluorescence imaging and electron microscopy showed that DC-SIGN-ligand complexes are targeted to late endosomes/lysosomes. Moreover, ligands internalized by DC-SIGN are efficiently processed and presented to CD4+ T cells. The distinct pattern of expression of C-type lectins on DCs in situ and their nonoverlapping Ag recognition profile hint to selective functions of these receptors to allow a DC to recognize a wide variety of Ags and to process these to induce T cell activation. These data point to a novel function of the adhesion receptor DC-SIGN as an efficient DC-specific Ag receptor that can be used as a target to induce viral and antitumor immunity.
Receptor-Facilitated Antigen Presentation Requires the Recruitment of B Cell Linker Protein to Igα
Authors: Siemasko Karyn , Skaggs Brian J. , Kabak Shara , Williamson Edward , Brown Bruce K. , Song Wenxia , Clark Marcus R. 
Published: April 2014

Abstract
Ags that cross-link the B cell Ag receptor are preferentially and rapidly delivered to the MHC class II-enriched compartment for processing into peptides and subsequent loading onto MHC class II. Proper sorting of Ag/receptor complexes requires the recruitment of Syk to the phosphorylated immunoreceptor tyrosine-based activation motif tyrosines of the B cell Ag receptor constituent Igα. We postulated that the Igα nonimmunoreceptor tyrosine-based activation motif tyrosines, Y176 and Y204, contributed to receptor trafficking. Igα(YΔF176,204)/Igβ receptors were targeted to late endosomes, but were excluded from the vesicle lumen and could not facilitate the presentation of Ag to T cells. Subsequent analysis demonstrated that phosphorylation of Y176/Y204 recruited the B cell linker protein, Vav, and Grb2. Reconstitution of Igα(YΔF176,204)/Igβ with the B cell linker protein rescued both receptor-facilitated Ag presentation and entry into the MHC class II-enriched compartment. Thus, aggregation accelerates receptor trafficking by recruiting two separate signaling modules required for transit through sequential checkpoints.
Hyperproliferative Response of a Monoclonal Memory CD8 T Cell Population Is Characterized by an Increased Frequency of Clonogenic Precursors
Authors: Arpin Christophe , Angelov Georgi , Walzer Thierry , Tomkowiak Martine , Belœil Laurent , Marvel Jacqueline 
Published: April 2014

Abstract
Strong memory T cell responses result partly from the selection of Ag-specific clones during immunization. In this study, we show that a monoclonal CD8 T cell population expressing a unique TCR is heterogeneous in terms of clonogenic potential following activation under optimal conditions. More importantly, the frequency of clonogenic cells is strongly increased among Ag-experienced cells, indicating that these cells were either generated or selected during the in vivo primary response. Moreover, strong proliferative responses of primed cells result from this enhanced frequency, as proliferating naive and primed cells display the same cycling parameters, i.e., lag time and intermitotic interval. Hence, these results suggest that the clonogenic potential of individual cells is imprinted before Ag encounter and that clonogenic precursors are selected or generated following in vivo activation.
Efficient Delivery of T Cell Epitopes to APC by Use of MHC Class II-Specific Troybodies
Authors: Lunde Elin , Western Karoline H. , Rasmussen Ingunn B. , Sandlie Inger , Bogen Bjarne 
Published: April 2014

AbstractA major objective in vaccine development is the design of reagents that give strong, specific T cell responses. We have constructed a series of rAb with specificity for MHC class II (I-E). Each has one of four different class II-restricted T cell epitopes genetically introduced into the first C domain of the H chain. These four epitopes are: 91–101 λ2315, which is presented by I-Ed; 110–120 hemagglutinin (I-Ed); 323–339 OVA (I-Ad); and 46–61 hen egg lysozyme (I-Ak). We denote such APC-specific, epitope-containing Ab “Troybodies.” When mixed with APC, all four class II-specific Troybodies were ∼1,000 times more efficient at inducing specific T cell activation in vitro compared with nontargeting peptide Ab. Furthermore, they were 1,000–10,000 times more efficient than synthetic peptide or native protein. Conventional intracellular processing of the Troybodies was required to load the epitopes onto MHC class II. Different types of professional APC, such as purified B cells, dendritic cells, and macrophages, were equally efficient at processing and presenting the Troybodies. In vivo, class II-specific Troybodies were at least 100 times more efficient at targeting APC and activating TCR-transgenic T cells than were the nontargeting peptide Ab. Furthermore, they were 100–100,000 times more efficient than synthetic peptide or native protein. The study shows that class II-specific Troybodies can deliver a variety of T cell epitopes to professional APC for efficient presentation, in vitro as well as in vivo. Thus, Troybodies may be useful as tools in vaccine development.
Correlation of Tissue Distribution, Developmental Phenotype, and Intestinal Homing Receptor Expression of Antigen-Specific B Cells During the Murine Anti-Rotavirus Immune Response
Authors: Youngman Kenneth R. , Franco Manuel A. , Kuklin Nelly A. , Rott Lusijah S. , Butcher Eugene C. , Greenberg Harry B. 
Published: April 2014

Abstract
The intestinal homing receptor, α4β7, helps target lymphocytes to Peyer’s patches (PP) and intestinal lamina propria (ILP). We have previously shown that protective immunity to rotavirus (RV), an intestinal pathogen, resides in memory B cells expressing α4β7. In this study, using a novel FACS assay, we have directly studied the phenotype of B cells that express surface RV-specific Ig during the in vivo RV immune response. During primary infection, RV-specific B cells first appear as large IgD−B220lowα4β7− and α4β7+ cells (presumptive extrafollicular, Ab-secreting B cells), and then as large and small IgD−B220highα4β7− cells (presumptive germinal center B cells). The appearance of B cells with the phenotype of large IgD−B220lowα4β7+ cells in PP and most notably in mesenteric lymph nodes coincides with the emergence of RV-specific Ab-secreting cells (ASC) in the ILP. Thus, these B lymphocytes are good candidates for the migratory population giving rise to the RV-specific ASC in the ILP. RV-specific long-term memory B cells preferentially accumulate in PP and express α4β7. Nine months after infection most RV-specific IgA ASC are found in PP and ILP and at lower frequency in bone marrow and spleen. This study is the first to follow changes in tissue-specific homing receptor expression during Ag-specific B cell development in response to a natural host, tissue-specific pathogen. These results show that α4β7 is tightly regulated during the Ag-specific B cell response to RV and is expressed concurrently with the specific migration of memory and effector B cells to intestinal tissues.
Evidence for the Extrathymic Origin of Intestinal TCRγδ+ T Cells in Normal Rats and for an Impairment of This Differentiation Pathway in BB Rats
Authors: Ramanathan Sheela , Marandi Leili , Poussier Philippe 
Published: April 2014

Abstract
The BB rat lyp mutation, one of its diabetes susceptibility genes, is responsible for a 5-fold decrease in the number of peripheral TCRαβ+ T cells. In this study we show that TCRγδ+ T cells are virtually undetectable among splenic T cells and intestinal intraepithelial T lymphocytes (IEL) of BB rats, while they account for 3 and 30% of these two T cell populations, respectively, in normal animals. It has been shown that murine IEL expressing TCRγδ develop extrathymically. We determined whether this is the case in rats. Athymic radiation chimeras reconstituted with normal hemopoietic precursors were devoid of donor-derived TCRαβ+ T cells and TCRγδ+ splenocytes but contained a normal number of TCRγδ+ IEL, suggesting that in unmanipulated rats some of the TCRγδ+ IEL may have an extrathymic origin. This was further supported by the observation that RAG1 transcripts are present in IEL of unmanipulated animals. No T cells developed in chimeras reconstituted with BB hemopoietic precursors, demonstrating that the BB rat lyp mutation inhibits both intrathymic and extrathymic development of TCRγδ+ T cells.
Administration of an Antigen at a High Dose Generates Regulatory CD4+ T Cells Expressing CD95 Ligand and Secreting IL-4 in the Liver
Authors: Watanabe Tomohiro , Yoshida Masaru , Shirai Yasuhiko , Yamori Masashi , Yagita Hideo , Itoh Toshiyuki , Chiba Tsutomu , Kita Toru , Wakatsuki Yoshio 
Published: April 2014

AbstractAgs administered orally at a high dose are absorbed in immunogenic forms and perfuse the liver, which raises a question regarding the relevance of hepatic lymphocyte activation to the systemic hyporesponsiveness against the ingested Ag. Oral administration of 100 mg of OVA to the mice led to massive cell death of OVA-specific (KJ1-26+) CD4+ T cells by Fas-Fas ligand (FasL)-mediated apoptosis in the liver, which was associated with the emergence of hepatic KJ1-26+CD4+ T cells expressing FasL. Hepatic CD4+ T cells in OVA-fed mice secreted large amounts of IL-4, IL-10, and TGF-β1 upon restimulation in vitro and inhibited T cell proliferation. Adoptive transfer of these hepatic CD4+ T cells to naive mice and subsequent antigenic challenge led to suppression of T cell proliferation as well as IgG Ab responses to OVA; this effect was mostly abrogated by a blocking Ab to FasL. i.p. administration of an Ag at a high dose also generated hepatic CD4+FasL+ T cells with similar cytokine profile as T cells activated by oral administration of Ags at a high dose. Finally, we did not see an increase in FasL+ cells in the hepatic CD4+Vβ8+ T cell subset of MRL/lpr/lpr mice given staphylococcal enterotoxin B, indicating the requirement for Fas-mediated signals. These hepatic CD4+FasL+ regulatory cells may explain the tolerogenic property of the liver and play roles in systemic hyporesponsiveness induced by an Ag administered at a high dose.
The Nonclassical Major Histocompatibility Complex Molecule Qa-2 Protects Tumor Cells from NK Cell- and Lymphokine-Activated Killer Cell-Mediated Cytolysis
Authors: Chiang Eugene Y. , Henson Maile , Stroynowski Iwona 
Published: April 2014

Abstract
The cytotoxic activity of NK cells is regulated by class I MHC proteins. Although much has been learned about NK recognition of class I autologous targets, the mechanisms of NK self-tolerance are poorly understood. To examine the role of a nonpolymorphic, ubiquitously expressed class Ib Ag, Q9, we expressed it on class I-deficient and NK-sensitive B78H1 melanoma. Presence of this Qa-2 family member on tumor cells partially protected targets from lysis by bulk lymphokine-activated killer (LAK) cells. H-2Kb-expressing B78H1 targets also reduced LAK cell activity, while H-2Db offered no protection. Importantly, blocking with F(ab′)2 specific for Q9 or removal of this GPI-attached molecule by phospholipase C cleavage restored killing to the level of vector-transfected cells. Experiments with LAK cells derived from H2b SCID and B6 mice established that NK1.1+TCR− NK and NK1.1+TCR+ LAK cells were the prevalent cytolytic populations inhibitable by Q9. Treatment of mice with poly(I:C) also resulted in generation of Q9-regulated splenic cytotoxicity. LAK cells from different mouse strains responded to Q9, suggesting that the protective effect of this molecule is not detectably influenced by Ly49 polymorphisms or the presence/absence of Q9 in NK-harboring hosts. We propose that Q9 expressed on melanoma cells serves as a ligand for yet unidentified NK inhibitory receptor(s) expressed on NK1.1+ NK/T cells.
Positive Effects of Glucocorticoids on T Cell Function by Up-Regulation of IL-7 Receptor α
Authors: Franchimont Denis , Galon Jérôme , Vacchio Melanie S. , Fan Samuel , Visconti Roberta , Frucht David M. , Geenen Vincent , Chrousos George P. , Ashwell Jonathan D. , O’Shea John J. 
Published: April 2014

Abstract
Despite the effects of glucocorticoids on immune function, relatively little is known about glucocorticoid-inducible genes and how their products may regulate lymphocyte function. Using DNA microarray technology to analyze gene expression in PBMC from healthy donors, we identified IL-7Rα as a glucocorticoid-inducible gene. This observation was confirmed at the mRNA and protein levels. Conversely, TCR signaling decreased IL-7Rα expression, and the relative strength of signaling between these two receptors determined the final IL-7Rα levels. The up-regulation of IL-7Rα by glucocorticoids was associated with enhanced IL-7-mediated signaling and function. Moreover, IL-7-mediated inhibition of apoptosis at increasing concentrations of glucocorticoids is consistent with enhanced cell sensitivity to IL-7 following glucocorticoid exposure. These observations provide a mechanism by which glucocorticoids may have a positive influence on T cell survival and function.
Functional Expression of the Chemokine Receptor CCR5 on Virus Epitope-Specific Memory and Effector CD8+ T Cells
Authors: Fukada Katsuhiko , Sobao Yuji , Tomiyama Hiroko , Oka Shinichi , Takiguchi Masafumi 
Published: April 2014

Abstract
Because the chemokine receptor CCR5 is expressed on Th1 CD4+ cells, it is important to investigate the expression and function of this receptor on other T cells involved in Th1 immune responses, such as Ag-specific CD8+ T cells, which to date have been only partially characterized. Therefore, we analyzed the expression and function of CCR5 on virus-specific CD8+ T cells identified by HLA class I tetramers. Multicolor flow cytometry analysis demonstrated that CCR5 is expressed on memory (CD28+CD45RA−) and effector (CD28−CD45RA− and CD28−CD45RA+) CD8+ T cells but not on naive (CD28+CD45RA+) CD8+ T cells. CCR5 expression was much lower on two effector CD8+ T cells than on memory CD8+ T cells. Analysis of CCR7 and CCR5 expression on the different types of CD8+ T cells showed that memory CD8+ T cells have three phenotypic subsets, CCR5+CCR7−, CCR5+CCR7+, and CCR5−CCR7+, while naive and effector CD8+ T cells have CCR5−CCR7+ and CCR5+CCR7− phenotypes, respectively. These results suggest the following sequence for differentiation of memory CD8+ T cells: CCR5−CCR7+→CCR5+CCR7+→CCR5+CCR7−. CCR5+CD8+ T cells effectively migrated in response to RANTES, suggesting that CCR5 plays a critical role in the migration of Ag-specific effector and differentiated memory CD8+ T cells to inflammatory tissues and secondary lymphoid tissues. This is in contrast to CCR7, which functions as a homing receptor in migration of naive and memory CD8+ T cells to secondary lymphoid tissues.
Antigen-Antibody Immune Complexes Empower Dendritic Cells to Efficiently Prime Specific CD8+ CTL Responses In Vivo
Authors: Schuurhuis Danita H. , Ioan-Facsinay Andreea , Nagelkerken Bas , van Schip Jolien J. , Sedlik Christine , Melief Cornelis J. M. , Verbeek J. Sjef , Ossendorp Ferry 
Published: April 2014

Abstract
Dendritic cells (DCs) require a maturation signal to acquire efficient CTL-priming capacity. In vitro FcγR-mediated internalization of Ag-Ab immune complexes (ICs) can induce maturation of DCs. In this study, we show that IC-induced DC maturation in vitro enables DCs to prime peptide-specific CD8+ CTLs in vivo, independently of CD4+ Th cells. Importantly, OVA/anti-OVA IC-treated DCs not only primed CD8+ CTLs to an exogenously loaded peptide nonrelated to OVA, but also efficiently primed CTLs against the dominant CTL epitope derived from the OVA Ag present in the ICs. Our studies show that ICs fulfill a dual role in priming of CD8+ CTL responses to exogenous Ags: enhancement of Ag uptake by DCs and activation of DCs, resulting in “license to kill.” These findings indicate that the presence of specific Abs can crucially affect the induction of cytotoxic cellular responses.
Tracking the Immunoregulatory Mechanisms Active During Allograft Tolerance
Authors: Sánchez-Fueyo Alberto , Weber Martina , Domenig Christoph , Strom Terry B. , Zheng Xin Xiao 
Published: April 2014

AbstractImmunoregulatory mechanisms dependent on regulatory CD4+ T cells are believed to be critical in the maintenance of peripheral tolerance to allografts. However, a detailed characterization of the effects of these regulatory T cells has been hampered by the absence of a simple means to track and study them. In this work we provide evidence that in a murine model of islet transplantation the interactions between alloaggressive and regulatory T cells can be studied in vitro and in vivo at the single-cell level. The observations made in both an in vitro coculture system and an in vivo CFSE-based adoptive transfer model indicate that lymphocytes from tolerant allograft recipients 1) proliferate weakly to donor strain allogeneic cells but vigorously to third-party strain cells; and 2) suppress the proliferation of naive syngeneic CD4+ and CD8+ T cells to donor tissue in a cell dose- and Ag-specific manner. These effects depend on the presence of CD4+CD25+ T cells and are neutralized by anti-CTLA4 mAb or rIL-2. The principal effect of anti-CTLA4 is directed against the naive, not regulatory, T cell population. These results can be replicated in vivo by transferring lymphocyte populations into transplant recipients, proving that the graft-protecting actions of regulatory T cells are blunted by a rise in the number of allodestructive T cells (pool size model) and depend on the presence of CD4+CD25+ T cells and the integrity of the CTLA4/B7 pathway.
Evolution of Ig DNA Sequence to Target Specific Base Positions Within Codons for Somatic Hypermutation
Authors: Shapiro Gary S. , Aviszus Katja , Murphy James , Wysocki Lawrence J. 
Published: April 2014

AbstractIg variable (V) region genes are subjected to a somatic hypermutation process as B lymphocytes participate in immune reactions to protein Ags. Although little is known regarding the mechanism of mutagenesis, a consistent hierarchy of trinucleotide target preferences is evident. Analysis of trinucleotide regional distributions predicted and we now empirically confirm the surprising finding that the framework 2 region of κ V region genes is highly mutable despite its importance to the structural integrity and function of the Ab molecule. Interestingly, much of this mutability appears to be focused on the third codon position where synonymous substitutions are most likely to occur. We also observed a trend for high predicted mutability for codon positions 1 and 2 in complementarity-determining regions. Consequently, amino acid replacements should occur at a higher rate in complementarity-determining regions than in framework regions due to the distribution and subsequent targeting of microsequences by the mutation mechanism. Our results reveal a subtle tier of V region gene evolution in which DNA sequence has been molded to direct mutations to specific base positions within codons in a manner that minimizes damage and maximizes the benefits of the somatic hypermutation process.
Allelic Polymorphism Synergizes with Variable Gene Content to Individualize Human KIR Genotype
Authors: Shilling Heather G. , Guethlein Lisbeth A. , Cheng Nathalie W. , Gardiner Clair M. , Rodriguez Roberto , Tyan Dolly , Parham Peter 
Published: April 2014

Abstract
Killer Ig-like receptor (KIR) genes are a multigene family on human chromosome 19. KIR genes occur in various combinations on different haplotypes. Additionally, KIR genes are polymorphic. To examine how allelic polymorphism diversifies KIR haplotypes with similar or identical combinations of KIR genes, we devised methods for discriminating alleles of KIR2DL1, -2DL3, -3DL1, and -3DL2. These methods were applied to 143 individuals from 34 families to define 98 independent KIR haplotypes at the allele level. Three novel 3DL2 alleles and a chimeric 3DL1/3DL2 sequence were also identified. Among the A group haplotypes were 22 different combinations of 2DL1, 2DL3, 3DL1, and 3DL2 alleles. Among the B group haplotypes that were unambiguously determined were 15 distinct haplotypes involving 9 different combinations of KIR genes. A and B haplotypes both exhibit strong linkage disequilibrium (LD) between 2DL1 and 2DL3 alleles, and between 3DL1 and 3DL2 alleles. In contrast, there was little LD between the 2DL1/2DL3 and 3DL1/3DL2 pairs that define the two halves of the KIR gene complex. The synergistic combination of allelic polymorphism and variable gene content individualize KIR genotype to an extent where unrelated individuals almost always have different KIR types. This level of diversity likely reflects strong pressure from pathogens on the human NK cell response.
A Change in the Structure of Vβ Chromatin Associated with TCR β Allelic Exclusion
Authors: Tripathi Rajkamal , Jackson Annette , Krangel Michael S. 
Published: April 2014

Abstract
To investigate chromatin control of TCR β rearrangement and allelic exclusion, we analyzed TCR β chromatin structure in double negative (DN) thymocytes, which are permissive for TCR β recombination, and in double positive (DP) thymocytes, which are postallelic exclusion and nonpermissive for Vβ to DβJβ recombination. Histone acetylation mapping and DNase I sensitivity studies indicate Vβ and DβJβ segments to be hyperacetylated and accessible in DN thymocytes. However, they are separated from each other by hypoacetylated and inaccessible trypsinogen chromatin. The transition from DN to DP is accompanied by selective down-regulation of Vβ acetylation and accessibility. The level of DP acetylation and accessibility is minimal for five of six Vβ segments studied but remains substantial for one. Hence, the observed changes in Vβ chromatin structure appear sufficient to account for allelic exclusion of many Vβ segments. They may contribute to, but not by themselves fully account for, allelic exclusion of others.