bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ig N-glycan orientation can influence interactions with the complement system.
Authors: White K D , Cummings R D , Waxman F J 
Published: December 2022

Abstract
This study was prompted by the paradoxical observation that a pair of dinitrophenyl-specific murine monoclonal IgG2a Abs had similar monosaccharide content and yet differed in their binding to lectins. The differential lectin-binding properties were lost when the Abs were denatured, suggesting that variations in lectin binding reflected the conformational accessibility of the N-glycans rather than intrinsic differences in the lectin binding capacity of the glycans themselves. This hypothesis was supported by experiments indicating that the degree to which the N-glycans on the Abs were reactive with beta-1,4-galactosyltransferase or susceptible to peptide N-glycosidase F corresponded directly to their relative accessibility to lectins. Moreover, the relative susceptibility to these enzymes and accessibility to lectins was inversely related to the capacity of the Abs to activate the classical pathway, suggesting that the orientation of the more accessible N-glycan might inhibit C1q binding. This hypothesis was supported by evidence that enzymatic cleavage of the more accessible N-glycan resulted in enhanced Clq, C4b, and C3b deposition. Conversely, removal of the less accessible N-glycan expressed by the other Ab inhibited C1q, C4b, and C3b deposition. The respective increase or decrease in C3b deposition on the two deglycosylated Abs was magnified when complement activation was performed in factor B-depleted serum, suggesting that N-glycan conformation primarily affects the classical pathway. Collectively, these data suggest that the orientation of the N-glycan expressed on Igs can profoundly influence interaction with the complement system.
Highly restricted TCR-alpha beta usage by autoreactive human T cell clones specific for DNA topoisomerase I: recognition of an immunodominant epitope.
Authors: Kuwana M , Medsger T A , Wright T M 
Published: December 2022

Abstract
Autoantibody responses to DNA topoisomerase I (Topo I) are highly specific to patients with systemic sclerosis (SSc). We recently demonstrated that Topo I-specific T cells are components of the T cell repertoire of patients with SSc and healthy individuals. These autoreactive T cells were essential for the Ag-specific activation of B cells resulting in anti-Topo I Ab production in vitro and therefore are believed to play a central role in autoantibody production. To characterize the Topo I-specific T cell, 15 T cell clones reactive with Topo I were generated from two patients with SSc and three healthy donors, all of whom shared the MHC class II allele DR11. All clones expressed a CD3+CD4+CD8- phenotype and were restricted by HLA-DR. When eight rTopo I fragments were tested individually as Ags, all clones responded to F5, which encodes amino acids 209 through 386 of Topo I, but not to F10, which encodes amino acids 209 through 276, indicating that one or more immunodominant epitopes on Topo I is located between amino acids 276 and 386. Analysis of TCR gene usage showed that the predominant V(alpha) segment of the functionally rearranged TCR-alpha gene was Vdelta5, which was used by seven clones. Most strikingly, all except one T cell clone had functional rearrangements of TCR beta-chain genes using the Vbeta120.la and Jbeta1.1 gene segments. Comparison of the CDR3 sequences of the TCRs revealed limited diversity, and, of note, all clones contained the amino acid motif PGGN (or minor variations) in the CDR3 of their TCR beta-chains. Furthermore, identical beta-chain CDR3 amino acid sequences were encoded by cDNAs generated from T cell clones derived from multiple individuals, including patients with SSc and healthy donors.
Nuclear import of HIV-1 DNA in resting CD4+ T cells requires a cyclosporin A-sensitive pathway.
Authors: Sun Y , Pinchuk L M , Agy M B , Clark E A 
Published: December 2022

Abstract
Using PCR to monitor early (LTR/LTR (long terminal repeat)) and late (LTR/gag) products of reverse transcription and the formation of HIV-1 LTR circles (indicating nuclear import), we explored the relationship between T cell activation signals and early events in the life cycle of HIV-1 infection. The combination of TCR ligation with either CD28 cross-linking or exogenous IL-2 was required for HIV-1 LTR circle formation in resting CD4+ T cells. Ligation of the TCR or CD28 receptors or addition of IL-2 alone did not induce this process. However, cross-linking the TCR, or IL-2 alone, unlike CD28 ligation, could induce the completion of viral reverse transcription. In contrast, the initiation of HIV-1 reverse transcription could occur in resting CD4+ T cells without any stimulation. Cyclosporin A (CsA), an inhibitor of T cell activation, completely blocked HIV-1 DNA nuclear import in activated CD4+ T cells. The completion of HIV-1 reverse transcription was blocked by CsA in infected CD4+ T cells activated by TCR ligation and IL-2, but not in cells stimulated by TCR and CD28 ligation. The costimulation of CD3 and CD28 mAbs in the presence of IL-2 could not overcome the CsA inhibitory effect on nuclear import of viral DNA. Therefore, the factor(s) involved in a CsA-sensitive pathway plays a critical role in HIV-1 DNA transport from the cytoplasm into the nucleus. Production and movement of HIV-1 DNA in resting CD4+ T cells require two signals: one signal from the TCR, which normally regulates the G0 to G1 transition, induces completion of viral reverse transcription; the other signal through CD28 or an IL-2R-dependent process is sensitive to CsA treatment and regulates viral DNA entry into the nucleus.
RAG1 and RAG2 in developing rabbit appendix subpopulations.
Authors: Fuschiotti P , Fitts M G , Pospisil R , Weinstein P D , Mage R G 
Published: December 2022

Abstract
The appendix of young rabbits is a site of primary heavy chain variable region-gene diversification and B cell selection. Appendix cells from 6- to 9-wk-old rabbits were stained and sorted for surface CD43 and IgM. We found that the CD43+IgM- and double-negative CD43-IgM- cells contained RAG1 transcripts and RAG2 protein. The presence of RAG gene products in appendix raised the possibility that pro-/pre-B cells were present in young rabbit appendix. Although an early suggestion that RAG2 plays a role in variable region-gene diversification by gene conversion in chicken bursa was not supported by studies of RAG2 protein in this tissue, we produced anti-rabbit RAG2 Abs to determine whether RAG2 protein was present in rabbit appendix, where cells that recently underwent gene conversion are found. We detected RAG2 protein in the four subpopulations of rabbit appendix lymphocytes, distinguished by surface CD43 and IgM markers. The appearance of RAG gene products during different stages of B cell maturation may reflect the function of the young rabbit appendix as a site of both B cell development and diversification.
Triggering of motile behavior in T lymphocytes via cross-linking of alpha 4 beta 1 and alpha L beta 2.
Authors: Hauzenberger D , Klominek J , Holgersson J , Bergström S E , Sundqvist K G 
Published: December 2022

Abstract
The mechanisms by which T lymphocytes are transformed from passively transported cells during circulation in the vascular system to actively migrating cells during extravasation are unknown. Therefore, the possibility that lymphocyte receptors are capable of inducing motility was investigated using a modified Boyden chamber assay. Cross-linking of alphaL beta2 and alpha4 beta1 on human T lymphocytes (T cell line and peripheral blood T cells) with immobilized mAbs induced motile behavior on fibronectin, laminin, collagen type IV, and poly-L-lysine. This induction of T cell migration was very potent and in most cases more efficient than pretreatment of the cells with phorbol esters. In contrast, control Abs to several other integrin- and non-integrin molecules present on T lymphocytes did not induce T cell migration. Anti-CD3 Abs themselves did not trigger motile behavior. However, anti-CD3 promoted T cell migration in the Boyden chamber system if present simultaneously with 40-kDa alpha4 beta1 binding fibronectin fragments or alphaL beta2 binding intercellular adhesion molecule-1/hIgG1Fc fusion proteins on the upper side of the filter. Abs to other surface components on T cells did not trigger motility when presented together with the 40-kDa fibronectin fragments or the intercellular adhesion molecule-1/hIgG1Fc fusion proteins. The induction of motile behavior could be blocked if the T cells were pretreated with Genistein and Calphostin C, indicating the involvement of a protein tyrosine kinase and protein kinase C-dependent signaling pathway in triggering of T cell motility via integrins. These results indicate that alphaL beta2 and alpha4 beta1 on T lymphocytes can selectively trigger motile behavior when cross-linked by their endothelial or extracellular matrix ligands. Furthermore, these data indicate that cross-linking of CD3 facilitates ligand binding and subsequent triggering of a motile phenotype by alphaL beta2 and alpha4 beta1.
CD4 ligands inhibit the formation of multifunctional transduction complexes involved in T cell activation.
Authors: Jabado N , Pallier A , Le Deist F , Bernard F , Fischer A , Hivroz C 
Published: December 2022

Abstract
Ligands binding to the CD4 molecule can inhibit TCR-mediated T cell activation. We have previously reported that transcription factors regulating the expression of the IL-2 gene, NF-AT, NF-kappaB, and AP-1, are targets of this inhibitory effect in an in vitro model using peripheral human CD4+ T cells activated by a CD3 mAb. Two T cell activation pathways involved in the regulation of these transcription factors, calcium flux and the p21ras pathway, were investigated as potential targets. Binding of HIV envelope glycoprotein gp160/gp120 or a CD4 mAb to the CD4+ T cells, prior to TCR/CD3 activation, inhibited the intracellular calcium elevation. This event strongly suggested an inhibition of PLCgamma1 activity. Tyrosine phosphorylation of PLCgamma1, induced by CD3 activation, was not affected, but its association with tyrosine-phosphorylated proteins, including a 62-kDa protein, was disrupted. This PLCgamma1-associated p62 was found to be immunoreactive to p62-Sam68 Abs. The activation-induced phosphorylation of two p21ras effectors, Raf-1 and Erk2, was inhibited by the CD4 ligands, indirectly pointing to inhibition of the p21ras activation pathway. In addition, we demonstrate that TCR activation of normal CD4+ T cells induced the formation of p120GAP and PLCgamma1-containing complexes. These complexes also contain other unidentified proteins. CD4 ligand binding induced a defective formation of these transduction complexes. This may result in inefficient signaling, partially accounting for the inhibitory effects of the CD4 ligands on both p21ras and calcium-activation pathways.
Class I- and class II-reactive TCRs coexpressed on CD4+ T cells both trigger CD4/CD8-shared and CD4-unique functions.
Authors: Asnagli H , Schmitt-Verhulst A M , Guimezanes A 
Published: December 2022

Abstract
CD4+ and CD8+ T cells emerge from thymic selection expressing a TCR restricted by MHC class II (TCRII) and MHC class I (TCRI), and upon Ag stimulation develop respectively into Th and CTL effector cells. The influence of thymic differentiation and antigenic stimulation on the determination of T cell functions was studied, with CD4+ T cells expressing a transgenic TCRI that reacts with the class I alloantigen H-2K(b) in a CD8-independent fashion. Such T cells additionally express a TCR, probably TCRII, in which the transgenic TCR beta-chain is associated with endogenously rearranged TCR alpha-chains. Upon in vitro stimulation with H-2K(b)-expressing cells, both CD8+ and CD4+ transgenic TCR+ T cells developed into CTL capable of killing Ag-expressing target cells through a perforin-dependent mechanism, and secreted IL-2 and IFN-gamma. Fas ligand-dependent killing could also be induced in both CD8+ and CD4+ in vitro stimulated T cells. The capacity to secrete IL-4 was restricted to the CD4+ T cells, however, suggesting that both CD8/CD4-shared and CD4-unique programs can be elicited by stimulation of CD4 T cells through a TCRI. Acquisition of CTL function was also induced upon class II alloantigen stimulation through the endogenously rearranged TCRII, which represents a polyclonal set of TCRs. IL-2, IFN-gamma, and after restimulation, IL-4, were also produced. Thus: 1) events associated with intrathymic selection influence the gene program activated in response to the same TCRI/APC interaction; and 2) CD4+ T cells expressing a TCRI and a TCRII can activate the same gene program after engagement of either one of these TCRs.
gamma1 heavy chain transgenes are responsive to IFN-gamma repression and CD40 ligation.
Authors: Elenich L A , Ford C S , Collins J T , Dunnick W A 
Published: December 2022

Abstract
The cis-acting elements that regulate production of germ-line transcripts from Ig heavy chain genes and subsequent switch recombination to those genes are poorly defined. We reported that a 17-kb transgene that includes Igamma1, Sgamma1, and Cgamma1 is regulated for germ-line transcription like the endogenous gamma1 gene. Transcripts from such transgenes are expressed only in B cells treated with both LPS and IL-4, and not in B cells treated with LPS alone or in thymocytes or nonlymphoid tissues. We have now found that transcripts from these transgenes are induced by treatment of transgenic B cells by IL-4 alone. As reported by others, IFN-gamma acts to inhibit the IL-4-mediated induction of germ-line transcripts of the endogenous gamma1 gene. We have found that LPS-plus IL-4-induced germ-line transcription of gamma1 transgenes is likewise inhibited by treatment of B cells with IFN-gamma, so the gamma1 gene must include the cis-acting element(s) that confers this inhibition. It is also known that CD40 ligation induces a modest amount of germ-line transcripts from the endogenous gamma1 gene and synergizes with IL-4 to induce large amounts of germ-line transcripts. The gamma1 transgenes are likewise induced by CD40 ligation, suggesting that the response element(s) for CD40 ligation can be found in the gamma1 gene. The promoter region for the germ-line transcripts and the I exon are likely to include some of these cis-acting elements. A series of transgenic mice with the promoter/Igamma1 region conferred low level, lymphoid-specific, RNA expression to a reporter gene, including significant expression in thymocytes. However, the promoter/Igamma1 transgenes were not regulated like the endogenous gamma1 gene, in that transcription in splenic B cells was not increased by LPS plus IL-4.
Costimulation of T cell proliferation by a chimeric B7-2 antibody fusion protein specifically targeted to cells expressing the erbB2 proto-oncogene.
Authors: Gerstmayer B , Altenschmidt U , Hoffmann M , Wels W 
Published: December 2022

Abstract
T cells require at least two signals for activation and clonal expansion. The first signal conferring specificity is initiated by interaction of the T cell receptor with antigenic peptides in the context of MHC molecules. The second, costimulatory signal can be provided by cell surface molecules on APCs such as B7-1 (CD80) and B7-2 (CD86), which interact with their counter-receptors on T cells. The absence of costimulatory signals presents one possible mechanism for tumor cells to escape immune surveillance. In experimental models transfection of B7 genes into tumor cells can result in T cell-dependent tumor rejection. We have developed a novel approach to direct the costimulatory B7-2 molecule to the surface of target cells. Our approach is based on a chimeric fusion protein that consists of the extracellular domain of human B7-2 fused to a single-chain Ab domain (scFv) specific for the ErbB2 protein, a type I growth factor receptor overexpressed in a high percentage of human adenocarcinomas. This B7-2(225)-scFv(FRP5) molecule expressed in the yeast Pichia pastoris and purified from culture supernatants is functionally active and binds to B7 counter-receptors and to ErbB2. B7-2(225)-scFv(FRP5) localizes specifically to the surface of ErbB2-expressing target cells, thereby providing a costimulatory signal that results in enhanced proliferation of syngeneic T cells. Our results suggest that effective tumor vaccines for cancer immunotherapy could be created by targeting such chimeric ligands to the surface of tumor cells.
Glutathione depletion is an early and calcium elevation is a late event of thymocyte apoptosis.
Authors: Macho A , Hirsch T , Marzo I , Marchetti P , Dallaporta B , Susin S A , Zamzami N , Kroemer G 
Published: December 2022

Abstract
According to current understanding, several metabolic alterations form part of the common phase of the apoptosis process. Such alterations include a disruption of the mitochondrial transmembrane potential (delta psi(m)), a depletion of nonoxidized glutathione (GSH) levels, an increase in the production of reactive oxygen species (ROS), and an elevation in cytosolic free Ca2+ levels. Using a cytofluorometric approach, we have determined each of these parameters at the single cell level in thymocytes or T cell hybridoma cells undergoing apoptosis. Regardless of the apoptosis induction protocol (glucocorticoids, DNA damage, Fas cross-linking, or CD3epsilon cross-linking), cells manifest a near-to-simultaneous delta psi(m) dissipation and GSH depletion early during the apoptotic process. None of the protocols for apoptosis inhibition (antioxidants, delta psi(m) stabilization, Bcl-2 hyperexpression, or inhibition of IL-1-converting enzyme) allowed for the dissociation of delta psi(m) disruption and GSH depletion, indicating that both parameters are closely associated with each other. At a later stage of the apoptotic process, cells manifest a near-simultaneous increase in ROS production and intracellular Ca2+ levels. Whereas the thapsigargin- or ionophore-induced elevation of calcium levels has no immediate consequence on delta psi(m') cellular redox potentials, or ROS production, pro-oxidants and menadione, an inducer of mitochondrial superoxide anion generation, cause a rapid (15 min) Ca2+ elevation. Together, these data suggest a two-step model of the common phase of apoptosis. After an initial delta psi(m) dissipation linked to GSH depletion (step 1), cells hyperproduce ROS with an associated disruption of Ca2+ homeostasis (step 2).
CD19 expression levels regulate B lymphocyte development: human CD19 restores normal function in mice lacking endogenous CD19.
Authors: Sato S , Steeber D A , Jansen P J , Tedder T F 
Published: December 2022

Abstract
Establishing signal transduction thresholds that regulate B lymphocyte responses to foreign Ags and tolerance to self Ags is critical for humoral immune responses. The effects of altered signaling thresholds in B lymphocytes were examined in CD19-deficient mice and transgenic mice that expressed human CD19 at varying densities. Human CD19 restored normal B cell function and development to CD19-deficient mice when expressed at levels comparable to those of circulating human B cells. While CD19 expression levels were found to be developmentally regulated and tightly controlled in normal mice, two- or threefold changes in cell surface CD19 expression in transgenic mice dramatically affected B cell development, mitogen responses, serum Ig levels, humoral immune responses, and germinal center formation. B cells from mice that overexpressed CD19 also had decreased levels of surface IgM and a cell surface phenotype consistent with increased signaling in these cells. These results suggest that CD19 may serve similar functions in humans and mice and that CD19 defines signaling thresholds in vivo for the Ag receptor as well as other cell surface receptors that regulate B lymphocyte selection, activation, and differentiation.
CD40 is a functional activation antigen and B7-independent T cell costimulatory molecule on normal human lung fibroblasts.
Authors: Sempowski G D , Chess P R , Phipps R P 
Published: December 2022

Abstract
CD40 is an important signaling and activation Ag found on certain bone marrow-derived cells. Recently, CD40 also has been shown to be expressed by mesenchymal cells, including human fibroblasts. Little is known about the role of CD40 in fibroblasts. The current study investigates the hypothesis that CD40 expressed on lung fibroblasts is an activation structure and mechanism for interaction with hemopoietic cells. Communication between resident tissue fibroblasts and T cells is necessary for normal wound healing, and can be pathologic, resulting in tissue fibrosis. Signaling through CD40 with soluble CD40 ligand stimulated fibroblast activation, as evidenced by mobilization of nuclear factor-kappaB and by induction of the proinflammatory and chemoattractant cytokines IL-6 and IL-8. IFN-gamma-primed lung fibroblasts costimulate T lymphocyte proliferation utilizing CD40, but not the well-studied costimulatory molecules B7-1 and B7-2. Data reported herein support the hypothesis that cognate interactions between tissue fibroblasts and infiltrating T lymphocytes, via the CD40/CD40L pathway, augment inflammation and may promote fibrogenesis by activating both cell types.
CD16-expressing CD8alpha alpha+ T lymphocytes in the intestinal epithelium: possible precursors of Fc gammaR-CD8alpha alpha+ T cells.
Authors: She J , Simpson S J , Gupta A , Holländer G , Levelt C , Liu C P , Allen D , van Houten N , Wang B , Terhorst C 
Published: December 2022

Abstract
T lymphocytes normally express their Ag receptors in association with the CD3 proteins, which include CD3zeta. In CD3zeta eta(null) mice thymic and peripheral T lymphocytes do not express the TCR/CD3 complex on their surface due to retention in the endoplasmic reticulum of the remaining polypeptide chains. However, intestinal intraepithelial lymphocytes (iIEL) of CD3zeta eta(null) mice do express surface TCR, because the Fc epsilonRI gamma chain replaced the CD3zeta chain in the TCR/CD3 complex. Here we report that in a subset of CD8alpha alpha+ iIEL the presence of the Fc epsilonRI gamma chain could be accounted for by the surface expression of the Fc gammaRIII(CD16) complex. Because in wild-type (wt) mice only CD16+ iIEL coexpressed Fc epsilonRI gamma and CD3zeta, we concluded that the presence of Fc epsilonRI gamma was dictated by its required participation of CD16 complex. CD8alpha alpha+ iIEL bearing CD16 and B220 were also detected in the intestinal mucosa of RAG-2(null) mice from 12 days after birth onward. Two independent experimental settings were used in an attempt to demonstrate that CD16+ iIEL matured into CD16- T cells. First, in the RAG-2(null) mice, iIEL responded to in vivo administration of an anti-CD3epsilon mAb by progression to a more mature stage of development, characterized by a loss of CD16 and B220. Secondly, a conversion to CD16- iIEL occurred upon transfer of wt CD16+ iIEL into RAG-2(null) mice. We conclude from these experiments that in both RAG-2(null) and wt mice, a precursor/progeny relationship may exists between CD16+ B220+ CD8alpha alpha+ and CD16- B220- CD8alpha alpha+ iIEL.