bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Role of T Cell Help in the Production of Antibodies Specific for Galα1–3Gal
Authors: Cretin Nathalie , Bracy Jennifer , Hanson Krista , Iacomini John 
Published: April 2014

Abstract
The majority of xenoreactive natural Abs in humans recognize the carbohydrate Ag present on pig tissue, Galα1–3Galβ1–4GlcNAc-R (αGal), synthesized by the enzyme UDP galactose:β-d-galactosyl-1,4-N-acetyl-d-glucosaminide α(1–3)galactosyltransferase or αGT. Using αGT knockout mice (GT0 mice), which like humans produce serum Abs that bind αGal, we examined the role of T cells in production of Abs specific for αGal. GT0 mice were crossed with TCR-β knockout mice (TCR-β0) to generate double-knockout mice (GT0/TCR-β0). While GT0/TCR-β+ mice exhibited an age-dependent increase in the serum titer of natural Abs specific for αGal, a similar increase was not observed in GT0/TCR-β0 mice, and the titer of αGal-specific Abs in double knockouts was significantly lower than in age-matched GT0/TCR-β+ mice. Immunization with pig cells resulted in a significant increase in the serum titer of αGal-specific Abs in GT0/TCR-β+ mice, but had no effect on the level of αGal-specific serum Abs in GT0/TCR-β0 mice. Treatment of GT0/TCR-β+ mice with anti-CD40L Abs before immunization with pig cells prevented sensitization to αGal. Our data suggest that the majority of αGal-specific Abs are T cell dependent and that production of αGal-specific Abs after sensitization can be prevented by blocking costimulatory pathways.
Cutting Edge: Precursor Frequency Affects the Helper Dependence of Cytotoxic T Cells
Authors: Mintern Justine D. , Davey Gayle M. , Belz Gabrielle T. , Carbone Francis R. , Heath William R. 
Published: April 2014

Abstract
Generation of CTL immunity often depends on the availability of CD4 T cell help. In this report, we show that CTL responses induced by cross-priming can be converted from CD4-dependent to CD4-independent by increasing the frequency of CTL precursors. In the absence of CD4 T cells, high numbers of CTL precursors were able to expand in number and become effector CTL. The ability of high frequencies of CD8 T cells to override help was not due to their ability to signal CD40 via expression of CD154. These findings suggest that when precursor frequencies are high, priming of CD8 T cell responses may not require CD4 T cell help.
Cutting Edge: Inducible Costimulator Protein Regulates Both Th1 and Th2 Responses to Cutaneous Leishmaniasis
Authors: Greenwald Rebecca J. , McAdam Alexander J. , Van der Woude Diane , Satoskar Abhay R. , Sharpe Arlene H. 
Published: April 2014

AbstractThe CD28 family member inducible costimulator protein (ICOS) has an important role in T cell differentiation and Ig class switching. To investigate the role of ICOS in vivo, ICOS−/− mice were infected s.c. with Leishmania mexicana. While wild-type mice developed large, cutaneous lesions, the growth of lesions and tissue histopathology was significantly delayed in ICOS−/− mice. ICOS−/− mice exhibited marked decreases in both Th1 and Th2 cytokine production and profound defects in L. mexicana-specific Ig isotype class switching to IgG1 and IgG2a and reduced total IgE levels. Our findings indicate that ICOS is a key regulator of both Th1 and Th2 responses and has a role in controlling cutaneous L. mexicana infection.
Cutting Edge: STAT6 Serves as a Positive and Negative Regulator of Gene Expression in IL-4-Stimulated B Lymphocytes
Authors: Schroder Andreas J. , Pavlidis Paul , Arimura Akinori , Capece Danielle , Rothman Paul B. 
Published: April 2014

Abstract
STAT6 plays an important role in IL-4-mediated B cell activation and differentiation. To identify primary and secondary target genes of STAT6, gene expression profiles of IL-4-stimulated B cells from STAT6+/+ vs STAT6−/− mice were compared. Statistical analysis revealed that 106 distinct probe sets including 70 known genes were differentially expressed between the 2 genotypes. These genes include transcription factors, kinases, and other enzymes, cell surface receptors, and Ig H chains. Surprisingly, although 31 genes were expressed at higher levels in STAT6+/+ B cells, 39 genes were expressed at higher abundance in STAT6−/− B cells. This result implies both positive and negative regulatory functions of STAT6 in IL-4-mediated gene expression. Furthermore, IL-4 induces expression of the transcription factor Krox20, which is required for maximal IL-4-induced transcription.
T-Bet Expression and Failure of GATA-3 Cross-Regulation Lead to Default Production of IFN-γ by γδ T Cells
Authors: Yin Zhinan , Chen ChangHung , Szabo Susanne J. , Glimcher Laurie H. , Ray Anuradha , Craft Joe 
Published: April 2014

Abstractγδ T cells predominantly produce IFN-γ upon activation. To determine the basis for default production of IFN-γ by γδ T cells, we analyzed the transcription factors T-box expressed in T cells (T-bet) and GATA-3. T-bet, absent in naive γδ cells, was induced upon TCR signaling, with IFN-γ production. T-bet also regulated IL-4 synthesis, as γδ cells isolated from T-bet-deficient mice displayed enhanced IL-4 levels with reduced IFN-γ production. Notably, T-bet expression after TCR signaling in γδ cells was not down-regulated by IL-4, in conjunction with a higher ratio of T-bet:GATA-3 expression than that found in CD4+ T cells. Indeed, overexpression of GATA-3 failed to inhibit IFN-γ secretion in γδ cells to the degree seen in CD4+ T cells. These results indicate that T-bet enhances IFN-γ secretion and suppresses IL-4 secretion in γδ cells, and that GATA-3 fails to counterbalance T-bet-mediated IFN-γ production, accounting for the default synthesis of IFN-γ by these T lymphocytes.
Inhibitory Effects of Apoptotic Cell Ingestion upon Endotoxin-Driven Myeloid Dendritic Cell Maturation
Authors: Stuart Lynda M. , Lucas Mark , Simpson Cathy , Lamb Jonathan , Savill John , Lacy-Hulbert Adam 
Published: April 2014

AbstractDendritic cells (DCs) are the sentinels of the immune system, able to interact with both naive and memory T cells. The recent observation that DCs can ingest cells dying by apoptosis has raised the possibility that DCs may, in fact, present self-derived Ags, initiating both autoimmunity and tumor-specific responses, especially if associated with appropriate danger signals. Although the process of ingestion of apoptotic cells has not been shown to induce DC maturation, the exact fate of these phagocytosing DCs remains unclear. In this paper we demonstrate that DCs that ingest apoptotic cells are able to produce TNF-α but have a diminished ability to produce IL-12 in response to external stimuli, a property that corresponds to a failure to up-regulate CD86. By single-cell analysis we demonstrate that these inhibitory effects are restricted to those DCs that have engulfed apoptotic cells, with bystander DCs remaining unaffected. These changes were independent of the production of anti-inflammatory cytokines TGF-β1 and IL-10 and corresponded with a diminished capacity to stimulate naive T cells. Thus, the ingestion of apoptotic cells is not an immunologically null event but is capable of modulating DC maturation. These results have important implications for our understanding of the role of clearance of dying cells by DCs not only in the normal resolution of inflammation but also in control of subsequent immune responses to apoptotic cell-derived Ags.
CD8+, αβ-TCR+, and γδ-TCR+ Cells in the Recipient Hematopoietic Environment Mediate Resistance to Engraftment of Allogeneic Donor Bone Marrow
Authors: Xu Hong , Exner Beate G. , Cramer Daniel E. , Tanner Michael K. , Mueller Yvonne M. , Ildstad Suzanne T. 
Published: April 2014

AbstractHistorically, conditioning for engraftment of hematopoietic stem cells has been nonspecific. In the present study, we characterized which cells in the recipient hematopoietic microenvironment prevent allogeneic marrow engraftment. Mice defective in production of αβ-TCR+, γδ-TCR+, αβ- plus γδ-TCR+, CD8+, or CD4+ cells were transplanted with MHC-disparate allogeneic bone marrow. Conditioning with 500 cGy total body irradiation (TBI) plus a single dose of cyclophosphamide (CyP) on day +2 establishes chimerism in normal recipients. When mice were conditioned with 300 cGy TBI plus a single dose of CyP on day +2, all engrafted, except wild-type controls and those defective in production of CD4+ T cells. Mice lacking both αβ- and γδ-TCR+ cells engrafted without conditioning, suggesting that both αβ- and γδ-TCR T cells in the host play critical and nonredundant roles in preventing engraftment of allogeneic bone marrow. CD8 knockout (KO) mice engrafted without TBI, but only if they received CyP on day +2 relative to the marrow infusion, showing that a CD8− cell was targeted by the CyP conditioning. The CD8+ cell effector function is mechanistically different from that for conventional T cells, and independent of CD4+ T helper cells because CD4 KO mice require substantially higher levels of conditioning than the other KO phenotypes. These results suggest that a number of cell populations with different mechanisms of action mediate resistance to engraftment of allogeneic marrow. Targeting of specific recipient cellular populations may permit conditioning approaches to allow mixed chimerism with minimal morbidity and could potentially avoid the requirement for myelotoxic agents altogether.
Preferential Recognition of Self Antigens Despite Normal Thymic Deletion of CD4+CD25+ Regulatory T Cells
Authors: Romagnoli Paola , Hudrisier Denis , van Meerwijk Joost P. M. 
Published: April 2014

Abstract
T cell tolerance to self Ags is in part established in the thymus by induction of apoptosis or anergy of potentially autoreactive thymocytes. Some autospecific T cells nevertheless migrate to peripheral lymphoid organs but are kept under control by the recently identified CD4+CD25+ regulatory T cell subset. Because these cells inhibit autoimmunity more efficiently than useful non-self Ag-specific immune responses, they are probably autospecific, posing important questions as to how they develop in the thymus. In this study we show that significantly more peripheral CD4+CD25+ regulatory T cells recognize self than non-self Ags. However, we also show for a large panel of endogenous superantigens as well as for self peptide/MHC complexes that autospecific CD4+CD25+ thymocyte precursors are normally deleted during ontogeny. Combined, our data firmly establish that the repertoire of regulatory T cells is specifically enriched in autospecific cells despite the fact that their precursors are normally susceptible to thymic deletion.
Early Growth Response Transcription Factors Are Required for Development of CD4−CD8− Thymocytes to the CD4+CD8+ Stage
Authors: Carleton Michael , Haks Mariëlle C. , Smeele Sigrid A. A. , Jones Allan , Belkowski Stanley M. , Berger Marc A. , Linsley Peter , Kruisbeek Ada M. , Wiest David L. 
Published: April 2014

AbstractProgression of immature CD4−CD8− thymocytes beyond the β-selection checkpoint to the CD4+CD8+ stage requires activation of the pre-TCR complex; however, few of the DNA-binding proteins that serve as molecular effectors of those pre-TCR signals have been identified. We demonstrate in this study that members of the early growth response (Egr) family of transcription factors are critical effectors of the signals that promote this developmental transition. Specifically, the induction of three Egr family members (Egr1, 2, and 3) correlates with pre-TCR activation and development of CD4−CD8− thymocytes beyond the β-selection checkpoint. Enforced expression of each of these Egr factors is able to bypass the block in thymocyte development associated with defective pre-TCR function. However, Egr family members may play somewhat distinct roles in promoting thymocyte development, because there are differences in the genes modulated by enforced expression of particular Egr factors. Finally, interfering with Egr function using dominant-negative proteins disrupts thymocyte development from the CD4−CD8− to the CD4+CD8+ stage. Taken together, these data demonstrate that the Egr proteins play an essential role in executing the differentiation program initiated by pre-TCR signaling.
Notch1 Perturbation of Hemopoiesis Involves Non-Cell- Autonomous Modifications
Authors: Kawamata Shin , Du Changchun , Li Kaijun , Lavau Catherine 
Published: April 2014

Abstract
To study the effects of Notch on hemopoiesis we used a bone marrow transduction/transplantation model and compared the transduced and nontransduced populations in reconstituted mice. While cells expressing a constitutively active form of murine Notch1 (Notch1IC) completely lacked B cells, a profound suppression of the B lineage was also seen in the nontransduced compartment. Experiments performed with retroviral supernatants of varying titers showed that the perturbations of B cell development among the nontransduced population correlated with the percentage of Notch1IC-transduced cells inoculated into the mice. The myeloid lineage of the Notch1IC-transplanted mice was altered as well, and this also affected the nontransduced population that had features of excessive maturation. To explore the basis of these non-cell-autonomous modifications we prepared conditioned medium from ex vivo cultures of Notch1IC-transplanted mice bone marrow and showed that it inhibited B cell maturation and promoted myeloid differentiation in a dose-dependent manner. Finally, we found that the T cell leukemia/lymphomas that occur in Notch1IC-transplanted mice were accompanied by abnormal maturation of nontransduced T cells in the bone marrow. These findings indicate that modifications of neighboring cells through non-cell-autonomous modifications take part in multiple facets of the activity of Notch on hemopoiesis.
Mutagenesis Within Human FcεRIα Differentially Affects Human and Murine IgE Binding
Authors: Mackay Graham A. , Hulett Mark D. , Cook Justin P. D. , Trist Halina M. , Henry Alistair J. , McDonnell James M. , Beavil Andrew J. , Beavil Rebecca L. , Sutton Brian J. , Hogarth P. Mark , Gould Hannah J. 
Published: April 2014

AbstractSoluble fragments of the α-chain of FcεRI, the high-affinity receptor for IgE, compete with membrane-bound receptors for IgE and may thus provide a means to combat allergic responses. Mutagenesis within FcεRIα is used in this study, in conjunction with the crystal structure of the FcεRIα/IgE complex, to define the relative importance of specific residues within human FcεRIα for IgE binding. We have also compared the effects of these mutants on binding to both human and mouse IgE, with a view to evaluating the mouse as an appropriate model for the analysis of future agents designed to mimic the human FcεRIα and attenuate allergic disease. Three residues within the C-C′ region of the FcεRI α2 domain and two residues within the α2 proximal loops of the α1 domain were selected for mutagenesis and tested in binding assays with human and mouse IgE. All three α2 mutations (K117D, W130A, and Y131A) reduced the affinity of human IgE binding to different extents, but K117D had a far more pronounced effect on mouse IgE binding, and although Y131A had little effect, W130A modestly enhanced binding to mouse IgE. The mutations in α1 (R15A and F17A) diminished binding to both human and mouse IgE, with these effects most likely caused by disruption of the α1/α2 interface. Our results demonstrate that the effects of mutations in human FcεRIα on mouse IgE binding, and hence the inhibitory properties of human receptor-based peptides assayed in rodent models of allergy, may not necessarily reflect their activity in a human IgE-based system.
Innate Direct Anticancer Effector Function of Human Immature Dendritic Cells. I. Involvement of an Apoptosis-Inducing Pathway
Authors: Janjic Bratislav M. , Lu Ganwei , Pimenov Alexei , Whiteside Theresa L. , Storkus Walter J. , Vujanovic Nikola L. 
Published: April 2014

AbstractDendritic cells (DCs) mediate cross-priming of tumor-specific T cells by acquiring tumor Ags from dead cancer cells. The process of cross-priming would be most economical and efficient if DCs also induce death of cancer cells. In this study, we demonstrate that normal human in vitro generated immature DCs consistently and efficiently induce apoptosis in cancer cell lines, freshly isolated noncultured cancer cells, and normal proliferating endothelial cells, but not in most normal cells. In addition, in vivo generated noncultured peripheral blood immature DCs mediate similar tumoricidal activity as their in vitro counterpart, indicating that this DC activity might be biologically relevant. In contrast to immature DCs, freshly isolated monocytes (myeloid DC precursors) and in vitro generated mature DCs are not cytotoxic or are less cytotoxic, respectively, suggesting that DC-mediated killing of cancer cells is developmentally regulated. Comparable cytotoxic activity is mediated by untreated DCs, paraformaldehyde-fixed DCs, and soluble products of DCs, and is destructible by proteases, indicating that both cell membrane-bound and secreted proteins mediate this DC function. Overall, our data demonstrate that human immature DCs are capable of inducing apoptosis in cancer cells and thus to both directly mediate anticancer activity and initiate processing of cellular tumor Ags.
Deficiency in the Anti-Apoptotic Protein A1-a Results in a Diminished Acute Inflammatory Response
Authors: Orlofsky Amos , Weiss Louis M. , Kawachi Nicole , Prystowsky Michael B. 
Published: April 2014

AbstractA1 is an anti-apoptotic member of the Bcl-2 family that is up-regulated in inflammatory myeloid cells. In the present study, we investigated the role of A1 in the maintenance of acute inflammation in mice. Mice possess three genes encoding highly related isoforms of A1. A1-a isoform mRNA was minimally expressed in resident peritoneal macrophages, but was present at a 300-fold higher level in inflammatory macrophages elicited by i.p. infection with Toxoplasma gondii. In comparison, A1-b and A1-d levels were 3- and 10-fold higher, respectively. Peritoneal leukocytosis was decreased in infected A1-a-deficient mice compared with wild-type, and this reduction was associated with a small but reproducible enhancement of survival. These effects could not be explained by an alteration in peritoneal parasite load, nor by increased apoptosis of infected inflammatory cells, which were protected from cell death by an A1-a-independent mechanism. Increased apoptosis in inflammatory neutrophils was observed sporadically in A1-a-deficient mice. Regulation of apoptosis by A1-a may be an important proinflammatory event in acute host responses.
Cell-Mediated Immunity Induced by RecombinantMycobacterium bovisBacille Calmette-Guérin Strains Against an Intracellular Bacterial Pathogen: Importance of Antigen Secretion or Membrane-Targeted Antigen Display as Lipoprotein for Vaccine Efficacy
Authors: Grode Leander , Kursar Mischo , Fensterle Joachim , Kaufmann Stefan H. E. , Hess Jürgen 
Published: April 2014

AbstractLive recombinant vaccines expressing defined pathogen-derived Ags represent powerful candidates for future vaccination strategies. In this study, we report on the differential induction of protective cell-mediated immunity elicited by different recombinant Mycobacterium bovis Bacille Calmette-Guérin (BCG) strains displaying p60 Ag of Listeria monocytogenes in secreted, cytosolic, or membrane-attached form for T cell recognition. Anti-listerial protection evoked by the membrane-linked p60 lipoprotein of rBCG Mp60 and that of the p60 derivative secreted by rBCG Sp60-40 were nearly equal, whereas cytosolic p60 displayed by rBCG Np60 failed to protect mice from listeriosis. In vivo depletion of CD4 or CD8 T cell subpopulations in rBCG Mp60-vaccinated mice before listerial challenge revealed interactions of both T cell subsets in anti-listerial protection. In rBCG Sp60-40-vaccinated animals, CD4 T cells predominantly contributed to anti-listerial control as shown by the failure of anti-CD8 mAb treatment to impair the outcome of listeriosis in rBCG Sp60-40-vaccinated mice after L. monocytogenes challenge. Hence, differential Ag display by rBCG influences cell-mediated immunity, which in turn may impact vaccine efficacy due to the different requirements of CD4 or CD8 T cells for pathogen elimination.
Oral DNA Vaccination In Utero Induces Mucosal Immunity and Immune Memory in the Neonate
Authors: Gerdts Volker , Snider Marlene , Brownlie Robert , Babiuk Lorne A. , Griebel Philip J. 
Published: April 2014

AbstractInfectious diseases are responsible for a significant number of deaths during the first weeks of life. Some of the salient pathogens include HSV, HIV, hepatitis B virus, group B streptococcus, Haemophilus sp., and Chlamydia sp. The vertical transmission of many of these pathogens significantly increases the risk of neonatal infection. We recently reported that oral DNA immunization in utero induced high serum Ab titers and cell-mediated immunity in fetal lambs. In this study, we demonstrate immune memory and mucosal immunity in newborn lambs following oral DNA immunization of the fetus. A single oral exposure in utero to plasmid DNA encoding a truncated form of glycoprotein D of bovine herpesvirus-1 induced detectable immune responses in 80% (12 of 15) of newborn lambs. There was no evidence for the induction of immune tolerance in nonresponding lambs. Responding lambs displayed both systemic and mucosal immune responses and reduced virus shedding following intranasal challenge. Furthermore, strong anamnestic responses were evident for at least 3 mo after birth. The efficacy of in utero oral DNA immunization was further demonstrated with the hepatitis B surface Ag, and protective serum Ab titers occurred in 75% of immunized lambs. Thus, the present investigation confirms that oral DNA immunization in utero can induce both mucosal and systemic immune responses in the neonate and that this immunity has the potential to prevent vertical disease transmission.
Streptococcus pneumoniaeEvades Complement Attack and Opsonophagocytosis by Expressing thepspCLocus-Encoded Hic Protein That Binds to Short Consensus Repeats 8–11 of Factor H
Authors: Jarva Hanna , Janulczyk Robert , Hellwage Jens , Zipfel Peter F. , Björck Lars , Meri Seppo 
Published: April 2014

AbstractStreptococcus pneumoniae is an important cause of upper and lower respiratory tract infections, meningitis, peritonitis, bacterial arthritis, and sepsis. Here we have studied a novel immune evasion mechanism of serotype 3 pneumococci, which are particularly resistant to phagocytosis. On their surfaces the bacteria express the factor H-binding inhibitor of complement (Hic), a protein of the pneumococcal surface protein C family. Using radioligand binding, microtiter plate assays, surface plasmon resonance analysis, and recombinant constructs of factor H, we located the binding site of Hic to short consensus repeats (SCRs) 8–11 in the middle part of factor H. This represents a novel microbial interaction region on factor H. The only other ligand known so far for SCRs 8–11 of factor H is C-reactive protein (CRP), an acute phase protein that binds to the pneumococcal C-polysaccharide. The binding sites of Hic and CRP within the SCR8–11 region were different, however, because CRP did not inhibit the binding of Hic and required calcium for binding. Binding of factor H to Hic-expressing pneumococci promoted factor I-mediated cleavage of C3b and restricted phagocytosis of pneumococci. Thus, virulent pneumococci avoid complement attack and opsonophagocytosis by recruiting functionally active factor H with the Hic surface protein. Hic binds to a previously unrecognized microbial interaction site in the middle part of factor H.