bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multiple sites on IL-8 responsible for binding to alpha and beta IL-8 receptors.
Authors: Schraufstätter I U , Barritt D S , Ma M , Oades Z G , Cochrane C G 
Published: January 2023

Abstract
To define the structural features important for IL-8 binding to its two known receptors, mutants of IL-8 and melanoma growth-stimulating activity (MGSA) and chimerae consisting of segments of these two chemokines were constructed and purified from the pGEX 2T Escherichia coli expression vector. IL-8 alpha and beta receptors were expressed stably and individually in 293 kidney epithelial cells and HL60 human leukemia cells. The Kd for IL-8 itself and copy numbers for both receptors in transfected cells were comparable. Competition binding with 125I-labeled IL-8, however, showed large differences for several of the IL-8 mutants between alpha and beta receptors. The amino-terminal ELR sequence was important for IL-8 binding to the alpha receptor, but not sufficient for high affinity binding. Both rabbit IL-8 and MGSA share the ELR sequence with human IL-8, but compete poorly with it. The carboxyl terminus distal to amino acid 50 does not seem to mediate high affinity binding to the alpha receptor. A rabbit IL-8/human IL-8 chimera that differs in only eight amino acids from the human IL-8 sequence, was 150-fold lower in its affinity for the alpha receptor than human IL-8. In contrast, both the amino and carboxyl termini appear to be important for binding to the beta receptor. If the ELR sequence of IL-8 was substituted with alanines or if the carboxyl terminus distal to C50 was replaced with the MGSA sequence, a reduction occurred in binding competition. If both changes were introduced simultaneously, binding was abolished. Binding of MGSA was completely prevented by replacement of the ELR sequence with alanines. Ca2+ mobilization in HL60 cells transfected with the alpha or beta receptor was used to assess cell stimulation. The various mutant forms of IL-8 induced receptor activity with a pattern of sensitivity parallel to the competition binding affinities, indicating that both receptors are active.
Increased gene expression of acetylcholine receptor and myogenic factors in passively transferred experimental autoimmune myasthenia gravis.
Authors: Asher O , Kues W A , Witzemann V , Tzartos S J , Fuchs S , Souroujon M C 
Published: January 2023

Abstract
The passive transfer of myasthenia gravis by injection of mAb against muscle acetylcholine receptor (AChR) alpha-subunit, results in increased expression of AChR subunit genes, mainly at synaptic regions. The gene expression of AChR and of other muscle-specific proteins is regulated in a similar manner in passively transferred experimental autoimmune myasthenia gravis (EAMG) and in AChR-induced EAMG. Administration of AChR-specific mAb leads to a significant reduction in muscle AChR content and to an elevation in the mRNA levels corresponding to the adult, synaptic type of the receptor, as shown by Northern blot and in situ hybridization analyses. The mRNA levels of the myogenic factors myogenin and MRF4 are also increased moderately, whereas MyoD transcript levels remain unchanged. Thus, passive transfer of EAMG by mAb directed to defined epitopes of AChR alpha-subunit provides a suitable model for analyzing and following the cascade of molecular events triggered by anti-AChR immunopathologic antibodies and may shed light on the regulatory mechanisms underlying the human disease as well.
CD2-CD4-CD8- lymph node T lymphocytes in MRL lpr/lpr mice are derived from a CD2+CD4+CD8+ thymic precursor.
Authors: Landolfi M M , Van Houten N , Russell J Q , Scollay R , Parnes J R , Budd R C 
Published: January 2023

Abstract
MRL lpr/lpr (lymphoproliferative, lpr) mice demonstrate an age-dependent lymphoproliferation and development of autoimmunity. Characteristic of the lymphoproliferation in these mice is the accumulation of large numbers of CD4-CD8-(CD4-8-),CD3+ T lymphocytes in their lymph nodes. The development of the CD4-8- cells, which also aberrantly express B220 and CD44 (Pgp-1) but are CD2-, has been shown to be thymus dependent. An unusual feature of lpr CD4-8-T lymphocytes is that although they appear unresponsive to stimulation, as defined by proliferation and IL-2 production, they have undergone thymic negative selection. As thymic deletion normally occurs at the CD4+CD8+ (CD4+8+) stage, this raises the dilemma that lpr CD4-8- T lymphocytes have either previously been CD4+8+, or they are able to undergo thymic selection as CD4-8- cells. We have addressed this question by examining the methylation status of the CD8 gene in MRL lpr CD4-8- lymph node cells. Demethylation of the CD8 gene has been shown to be an indicator of previous CD8 expression. We find that the CD8 gene in lpr CD4-8- lymph node cells, as well as in the abnormal B220+ CD4-8- lpr thymocytes, is demethylated, suggesting that these cells have previously expressed CD8. In addition, we find that the lpr CD4+8+ thymocyte population contains an increased percentage of atypical B220+, CD44+ cells that are virtually all CD2+. Taken together, these data are consistent with the lpr CD2-CD4-8- population of LNC having arisen from a CD2+ CD4+8+ thymic stage of differentiation.
Induction of HIV-specific cytotoxic T lymphocytes in vivo with hybrid HIV-1 V3:Ty-virus-like particles.
Authors: Layton G T , Harris S J , Gearing A J , Hill-Perkins M , Cole J S , Griffiths J C , Burns N R , Kingsman A J , Adams S E 
Published: January 2023

Abstract
In general, it has proven difficult to induce CTL responses using simple proteins or peptides without resorting to specialized adjuvants. In this study we show that particulate polymeric Ag in the form of hybrid Ty virus-like particles carrying the V3 region of HIV-1 gp120/160 envelope protein (V3:Ty-VLP) induce V3-specific CTL in BALB/c mice in the absence of adjuvant or lipid vehicle. In vitro restimulation of splenocytes with V3 peptide was necessary in order to generate effector CTL. Th cell activation was not required for this in vitro restimulation phase. The CTL induced by the V3:Ty-VLP were CD8+ve, H-2d-restricted, and HIV-1 isolate-specific (IIIB or MN). Co-administration of IIIB V3:Ty-VLP and MN V3:Ty-VLP primed both IIIB and MN V3-specific CTL. However, only IIIB V3-specific CTL were primed by hybrid Ty-VLP carrying IIIB, MN, and RF V3 loop sequences on the same particle indicating that there is intra- but not intermolecular competition between CTL epitopes. In direct comparisons, V3:Ty-VLP were substantially more potent than rgp120. Rgp160 and a 40mer IIIB V3 peptide both failed to prime V3-specific CTL. These data suggest that the particulate nature of hybrid Ty-VLP facilitates uptake into APC with subsequent access to the MHC class I processing pathway and that they may be useful vaccine vehicles for inducing cytolytic immunity against HIV-1 and other intracellular pathogens.
Possible pathogenic role of cationic anti-DNA autoantibodies in the development of nephritis in patients with systemic lupus erythematosus.
Authors: Suzuki N , Harada T , Mizushima Y , Sakane T 
Published: January 2023

Abstract
Extensive studies in murine models of lupus nephritis have shown that cationic anti-DNA autoantibodies have nephritogenic potential. We have investigated whether cationic anti-DNA antibodies of IgG class are also produced in vivo in patients with active lupus nephritis. Antibodies against DNA in the sera from patients with SLE were purified by affinity chromatography on DNA-cellulose, followed by nonequilibrium pH gradient electrophoresis and SDS-PAGE. The highly cationic anti-DNA antibodies of IgG class were prominent in the nonequilibrium pH gradient electrophoresis-immunoblots of the antibodies from the patients with active lupus nephritis. Decreased proteinuria after successful treatment with prednisolone was associated with disappearance of the cationic anti-DNA antibodies in the circulation. The cationic anti-DNA antibodies did bind to heparan sulfate, which is a major glycosaminoglycan in glomerular basement membrane, much better than did neutral anti-DNA antibodies. The results suggest that the cationic anti-DNA autoantibodies may play a certain role in the development of lupus nephritis. Our study demonstrates the strong association between the presence of cationic anti-DNA antibody and the development of lupus nephritis in humans.
Detection of glycosylation abnormality in rheumatoid IgG using N-acetylglucosamine-specific Psathyrella velutina lectin.
Authors: Tsuchiya N , Endo T , Matsuta K , Yoshinoya S , Takeuchi F , Nagano Y , Shiota M , Furukawa K , Kochibe N , Ito K 
Published: January 2023

Abstract
Although the galactose deficiency in the Asn297-linked sugar chains of serum IgG from patients with rheumatoid arthritis (RA) has been established, structural analysis of sugar chains has not been readily available. Psathyrella velutina lectin (PVL) preferentially interacts with the N-acetylglucosamine beta 1--&gt;2Man group, exposed at the termini of sugar chains in agalacto IgG. Biotinylated PVL reacted strongly in Western blotting with H chains of IgG derived from patients with RA. An ELISA-based assay for the detection of agalacto IgG was developed using recombinant protein G and biotinylated PVL in combination, and the screening of patients' sera was performed. PVL binding of serum IgG significantly correlated with percentage of galactose-deficient IgG determined by the structural analysis. Age-related slight increase in PVL binding was observed among normal controls. Patients with RA showed significantly higher PVL binding (37.90 +/- 42.25 U/ml, n = 93) as compared with normal controls (5.75 +/- 2.92 U/ml, n = 112) (p = 0.0001). Patients with SLE showed lower but still significant PVL binding (17.86 +/- 5.18 U/ml, n = 10, p = 0.0001). PVL binding correlated with C-reactive protein level in serial analysis of individual RA patients, and was significantly higher in the synovial fluid compared with paired serum samples. PVL binding assay may provide an ideal tool for the simple and sensitive detection of agalacto IgG.
Influence of the T cell receptor alpha-chain on T cell reactivity and tolerance to Mls-1 in T cell receptor beta-chain transgenic mice.
Authors: Blackman M A , Smith H P , Le P , Woodland D L 
Published: January 2023

Abstract
Previous analyses of a TCR V beta 8.1 transgenic mouse revealed multiple mechanisms of tolerance to the retroviral superantigen, Mls-1. Whereas some T cells were clonally deleted in the thymus, others became anergic in the periphery, or remained unaffected by the expression of Mls-1. In addition, a strong correlation between TCR alpha-chain usage and Mls-1 reactivity of individual transgenic V beta 8.1+ T cell hybridomas was established. Based on these observations, we speculated that the different mechanisms of tolerance were a consequence of the alpha-chain-mediated differences in Mls-1 reactivity. In the current studies, we make use of a V alpha 2-specific mAb to directly examine the role of the alpha-chain on tolerance in this transgenic model. We show, first, that V alpha 2+ CD4+ T cells, as a group, are relatively less Mls-1-reactive, and are elevated twofold in the periphery of Mls-1+ compared with Mls-1-V beta 8.1 transgenic mice. This elevated expression is also seen in the V alpha 2+ CD4+ population of mature thymocytes, but not in immature thymocytes. Second, Mls-1-induced neonatal tolerance in Mls-1-negative mice caused an increase of V alpha 2+ CD4+ T cells, comparable with the frequency of expression in transgenic mice that endogenously expressed Mls-1. Third, we have demonstrated a general correlation between the age-dependent increase in Mls-1-expression and the levels of V alpha 2+ CD4+ T cells during the first 4 wk of life. Taken together, these data suggest that the over-expression of V alpha 2+ CD4+ T cells in Mls-1+ mice is a consequence of mechanisms of tolerance, predominantly mediated by preferential lack of clonal deletion in the thymus. These data support the idea that clonal deletion is a competitive process and the influence of the TCR alpha-chain on the strength of Mls-1 reactivity of individual V beta 8.1+ transgenic T cells controls their susceptibility to clonal deletion.
Lack of voltage sensitive potassium channels and generation of membrane potential by sodium potassium ATPase in murine T lymphocytes.
Authors: Ishida Y , Chused T M 
Published: January 2023

Abstract
Voltage sensitive K+ channels, which are responsible for generation of membrane potential in most cells, are functionally absent in about one-third of peripheral murine T cells and greatly reduced in the rest as shown by resistance of their membrane potential to changes in extracellular potassium concentration and failure of K+ channel dependent volume regulation. Despite the absence of voltage- sensitive K+ channels, the membrane potential of peripheral T cells is between -60 and -70 mV, the same as thymocytes. A total of 40 to 70 mV of the membrane potential of peripheral T cells is produced by the direct electrogenic action of the asymmetric Na+K+ ATPase pump because the cells are depolarized by ouabain, an inhibitor of the pump, removal of extracellular potassium or reduction of temperature. The residual, ouabain-resistant membrane potential, is sensitive to the K+ channel blocker, quinine, and thus due to electrodiffusion through K+ channels. Na+ and K+ turnover, and sensitivity to ouabain, are the same in peripheral T cells and thymocytes. The predominant mechanism of membrane potential generation changes during T lymphocyte differentiation from electrodiffusion in the thymus to electrogenic in peripheral T cells and back to electrodiffusion upon peripheral cell activation.
Identification of a G protein coupled receptor induced in activated T cells.
Authors: Kaplan M H , Smith D I , Sundick R S 
Published: January 2023

Abstract
Many genes are induced after T cell activation to make a cell competent for proliferation and ultimately, function. Many of these genes encode surface receptors for growth factors that signal a cell to proliferate. We have cloned a novel gene (clone 6H1) that codes for a member of the G protein-coupled receptor superfamily. This gene was isolated from a chicken activated T cell cDNA library by low level hybridization to mammalian IL-2 cDNA probes. The 308 amino acid open reading frame has seven hydrophobic, presumably transmembrane domains and a consensus site for interaction with G proteins. Tissue distribution studies suggest that gene expression is restricted to activated T cells. The message appears by 1 h after activation and is maintained for at least 45 h. Transcription of 6H1 is induced by a number of T cell stimuli and is inhibited by cyclosporin A, but not by cycloheximide. This is the first description of a member of this superfamily expressed specifically in activated T cells. The gene product may provide a link between T cell growth factors and G protein activation.
CD53, a protein with four membrane-spanning domains, mediates signal transduction in human monocytes and B cells.
Authors: Olweus J , Lund-Johansen F , Horejsi V 
Published: January 2023

Abstract
CD53 is a member of a novel family of molecules with four presumably membrane-spanning domains. The structure and functional characteristics of these molecules indicate that they may play an important role in transmembrane communication. We therefore investigated whether CD53 is involved in activation of human leukocytes. Cross-linking of cell-bound F(ab')2 fragments of two different anti-CD53 mAb with F(ab')2 anti-mouse Ig led to cytoplasmic calcium fluxes in B cells, monocytes, and granulocytes and activation of the monocyte oxidative burst. These responses were specific for CD53, as cross-linking of CD11a, CD18, CD35, CD43, CD44, CD45, or CDw50 did not induce leukocyte activation. Low concentrations of staurosporine (10 to 20 nM) completely inhibited PMA-mediated activation, but had no effect on CD53-mediated calcium fluxes and inhibited only partially CD53-mediated oxidative burst. This suggests that CD53-mediated signaling is largely independent of protein kinase C. CD53-mediated calcium fluxes were inhibited by high concentrations of staurosporine (300 to 500 nM) but not by ADP-ribosylating toxins, suggesting dependence on tyrosine kinases rather than GTP-binding proteins. The results indicate that CD53, like several other leukocyte Ag with four membrane-spanning regions, has the ability to mediate cell activation, and support the view that these molecules are involved in transmembrane communication.
Mechanisms of cytotoxicity used by human peripheral blood CD4+ and CD8+ T cell subsets. The role of granule exocytosis.
Authors: Smyth M J , Ortaldo J R 
Published: January 2023

Abstract
The broad lytic properties of high buoyant density CD4+ and CD8+ T cell subsets were examined by activating these populations with anti-CD3 mAb and IL-2 for 1 to 5 days and testing their cytotoxic activity against various target cells. The effects of a variety of metabolic inhibitors and anti-TNF antibodies were examined to distinguish several different mechanisms of cytotoxicity used by CD4+ and CD8+ T cell effectors isolated from human PBL. In particular, activated CD4+ and CD8+ T cells were cytotoxic when redirected by an anti-nitrophenyl (NP)-anti-CD3 mAb heteroconjugate against NP-modified nucleated target cells (TC) and anucleated SRBC and also lysed L929 in a TNF-alpha-dependent manner. CD4+ and CD8+ T cells displayed distinct pathways of antibody-redirected lysis against NP-EL4, yet common mechanisms of SRBC redirected lysis by CD4+ and CD8+ efforts were implied by a similar pattern of sensitivity to cholera toxin, cyclosporin A (CsA), and EGTA. CsA inhibited CD4+ and CD8+ T cell redirected lysis of SRBC, but not EL4, suggesting that T cells redirectedly lyse nucleated and anucleated TC by different mechanisms. Cholera toxin, CsA, or EGTA pretreatment also significantly inhibited their release of alpha-N-benzyloxycarbonyl-L-lysine-thiobenzylester-esterase activity suggesting that degranulation of CD4+ and CD8+ effectors may be a critical step in their redirected lysis of SRBC. Overall, these findings suggested that activated human PBL CD4+ or CD8+ effectors can lyse TC by at least three distinct mechanisms: 1) a CsA-sensitive redirected lysis of SRBC that correlates with exocytosis and presumably occurs via membrane lesions; 2) a CsA-insensitive redirected lysis of NP-modified nucleated TC that does not appear to involve exocytosis and is metabolically distinct in activated CD4+ and CD8+ T cell effectors; and 3) a direct TNF-dependent lysis of TNF-sensitive TC.
CD8 inhibits signal transduction through the T cell receptor in CD4-CD8- thymocytes from T cell receptor transgenic mice reconstituted with a transgenic CD8 alpha molecule.
Authors: van Oers N S , Teh S J , Garvin A M , Forbush K A , Perlmutter R M , Teh H S 
Published: January 2023

Abstract
T cell repertoire selection processes involve intracellular signaling events generated through the TCR. The CD4 and CD8 coreceptor molecules can act as positive regulators of TCR signal transduction during these developmental processes. In this report, we have used TCR transgenic mice to determine whether TCR signaling can be modulated by the CD8 coreceptor molecule. These mice express on the majority of their T cells a TCR specific for the male (H-Y) Ag presented by the H-2Db MHC class I molecule. We show that CD4-CD8-, but not CD4-CD8+, thymocytes expressing the H-Y TCR responded with high intracellular calcium fluxes to TCR/CD3 stimulation without extensive receptor cross-linking. To examine the effects of CD8 expression on intracellular signaling responses in the CD4-CD8- cells, the H-Y TCR transgenic mice were mated with transgenic mice that constitutively expressed the CD8 alpha molecule on all T cells. The expression of the CD8 alpha alpha homodimer in the CD4-CD8-thymocytes led to impaired intracellular calcium responses and less efficient protein tyrosine phosphorylation of substrates after TCR engagement. In male H-2b H-Y transgenic mice, the majority of thymocytes have been deleted with the surviving cells expressing a high density of the transgenic TCR and exhibiting either a CD4-CD8- or CD4-CD8lo phenotype. It has been postulated that these cells escaped deletion by down-regulating the CD8 molecule. In the H-Y TCR/CD8 alpha double transgenic male mice, the CD4-CD8lo cells were completely eliminated as a result of CD8 alpha expression. However, the CD4-CD8- T cells were not deleted despite normal levels of the CD8 alpha transgene expression. These results suggest that the CD4-CD8- thymocytes may not be susceptible to the same deletional mechanisms as other thymocytes expressing TCR-alpha beta.
Analysis of the preexisting and nuclear forms of nuclear factor of activated T cells.
Authors: Jain J , Miner Z , Rao A 
Published: January 2023

Abstract
The nuclear factor of activated T cells (NF-AT)3 is an inducible DNA-binding protein that is essential for transcriptional induction of the IL-2 gene during T cell activation. NF-AT is thought to consist of two components: a ubiquitous, inducible nuclear component that we have identified as Fos and Jun proteins, and a preexisting, T cell-specific component (NF-ATp) which is the target for the immunosuppressive agents cyclosporin A (CsA) and FK506. We have previously shown that nuclear extracts from activated T cells form two inducible NF-AT complexes with an oligonucleotide corresponding to the distal NF-AT site of the murine IL-2 promoter, although hypotonic extracts of unstimulated T cells form a single complex containing NF-ATp. We show that the ability to detect NF-ATp in a gel shift assay, which is essential for purification and biochemical studies of this protein, is strikingly dependent on the precise sequence of the NF-AT oligonucleotide used as the labeled probe. Moreover we present evidence that the component that forms the faster-migrating ("lower") nuclear NF-AT complex is derived by a calcium-dependent, cyclosporin-sensitive, posttranslational modification of NF-ATp, and that Fos and Jun proteins stabilize its interaction with DNA. The results are discussed in the context of a model relating the two nuclear NF-AT complexes to NF-ATp.
Immunization of mice with Yersinia enterocolitica leads to the induction of antithyrotropin receptor antibodies.
Authors: Luo G , Fan J L , Seetharamaiah G S , Desai R K , Dallas J S , Wagle N , Doan R , Niesel D W , Klimpel G R , Prabhakar B S 
Published: January 2023

Abstract
It is well established that autoimmune Graves' disease, which is characterized by hyperthyroidism, is mediated by autoantibodies to the thyrotropin receptor (TSHr). Although what initially triggers this autoantibody response is not known, a number of studies have suggested that Yersinia enterocolitica, an enterobacteria, could initiate the immune response against the TSHr. In this study, we produced antibodies against purified extracellular domain of human TSHr (ETSHr) and showed that anti-ETSHr antibodies reacted with envelope preparations from Y. enterocolitica. This reactivity was specifically blocked by preincubating sera with purified ETSHr. Moreover, antibodies reactive with ETSHr were induced by immunizing mice with Y. enterocolitica but not with Shigella flexneri SA100, Salmonella typhimurium TML, and Listeria monocytogenes. Anti-Y. enterocolitica antisera specifically reacted with the ETSHr protein and the reactivity could be blocked both by ETSHr and Y. enterocolitica envelope proteins. Our studies provide the first direct evidence that immunization with Y. enterocolitica can lead to the production of antibodies capable of reacting with TSHr and might provide the initial stimulus necessary for breakdown of self-tolerance to TSHr, eventually leading to the development of autoimmunity to TSHr.