bluuebunny/crossref_metadata_2025_split huggingface dataset:
B cell Ag receptor mediates different types of signals in the protein kinase activity between immature B cell and mature B cell.
Authors: Igarashi H , Kuwahara K , Nomura J , Matsuda A , Kikuchi K , Inui S , Sakaguchi N 
Published: December 2022

Abstract
Ig receptor (IgR) on the surface of B cells mediates the Ag-specific stimulatory signal for B cell proliferation and differentiation. In immature B cells, the stimulatory signal causes an inhibitory effect which is believed to be a key phenomenon in B cell tolerance or B cell anergy. Here, we studied the molecular mechanism of the inhibitory response of the IgR-mediated signal transduction that results in the programmed cell death of immature B cells. To analyze the downstream molecules of the IgR-mediated signal transduction, we prepared a mAb against a 160-kDa membrane protein (p160) that can coprecipitate the kinase molecule(s) acting on serine, threonine, and tyrosine residues. Anti-IgR stimulation induces the increase of the kinase activity coprecipitated with the p160 protein in mature B cell BAL17 and normal adult spleen B cells. This result suggest that the p160-associated kinase activity is one of the downstream events of the IgR-mediated signal transduction cascade. Interestingly, immature B cell lymphoma WEHI-231 and the neonatal spleen B cells showed the adverse reaction of the p160-associated kinase which results in the transient loss of the kinase activity. Moreover, the transient decrease of the p160-associated kinase was caused by the tyrosine phosphatase activity induced by the stimulation of IgR in WEHI-231. The results suggest that this molecular difference in the downstream events of the IgR-mediated signal transduction between immature B cells and mature B cells already begins at the transmembrane level in the IgR-mediated signal transduction pathway.
Co-receptor (CD4/CD8) engagement enhances CD3-induced apoptosis in thymocytes. Implications for negative selection.
Authors: McConkey D J , Fosdick L , D'Adamio L , Jondal M , Orrenius S 
Published: December 2022

Abstract
Negative selection of self-reactive immature T cells is mediated by TCR engagement and is thought to occur via apoptosis (programmed cell death). The requirement for the co-receptors CD4 and CD8 in negative selection has been demonstrated, but the biochemical mechanisms underlying their involvement in this process remain undefined. Here we present evidence that co-receptor engagement dramatically enhances CD3-induced endonuclease activation and cell death characteristic of apoptosis in immature thymocytes. The responses are associated with increased tyrosine phosphorylation of a number of cellular substrates, including the gamma isoform of phospholipase C, and with increased association of tyrosine phosphoproteins, including the protein tyrosine kinase p56lck, with the TCR complex. Co-receptor engagement also potentiated CD3-mediated Ca2+ increases via a mechanism dependent upon tyrosine kinase activation. Sustained Ca2+ availability was found to be necessary for endonuclease activation and apoptosis to occur. We suggest that CD4 and CD8 may participate in negative selection by enhancing TCR/CD3-induced tyrosine kinase activation and sustained Ca2+ increases that lead to endonuclease activation and apoptosis in self-reactive CD4+ CD8+ thymocytes.
CD59 costimulation of T cell activation. CD58 dependence and requirement for glycosylation.
Authors: Menu E , Tsai B C , Bothwell A L , Sims P J , Bierer B E 
Published: December 2022

Abstract
In addition to the TCR-CD3 complex, T lymphocytes can be activated via another surface glycoprotein, the CD2 molecule. CD58 is the principal ligand for human CD2; CD59 and CD48 are two additional, low affinity ligands that have been defined for CD2. In this study, we have explored the role of CD59 in T cell activation. We have expressed human rCD58 and rCD59 molecules in Chinese hamster oocytes (CHO), and tested paraformaldehyde-treated transfectants for the ability to promote proliferation of and IL-2 secretion from PBMC and human purified T cells. We have shown that CD59 enhanced CD58-dependent T cell proliferation and IL-2 secretion in the presence of suboptimal concentration of PHA or a submitogenic combination of stimulatory anti-CD2 mAbs, presence of suboptimal concentration of PHA or a submitogenic combination of stimulatory anti-CD2 mAbs, T11-2 + T11-3. CD59-dependent costimulation was dependent on several factors including the level of co-expression of CD58, the ratio of CHO cell transfectants to T cells added in culture, the concentration of mitogen, and also donor-dependent differences. As expected, CD59 costimulation of CD58-dependent T cell proliferation was inhibited by Abs directed against CD59, CD58, and CD2. In our hands, the CD59 molecule itself, in the absence of CD58, was unable to support proliferation alone even in the presence of exogenous recombinant IL-1, IL-2, or IL-6. Finally, the ability of CD59 to enhance CD58-dependent T cell responses was shown to be dependent on N-glycosylation of CD59 at amino acid Asn18.
The role of the Fas lytic pathway in a perforin-less CTL hybridoma.
Authors: Walsh C M , Glass A A , Chiu V , Clark W R 
Published: December 2022

Abstract
The murine CTL hybridoma PMMI has been shown by the most sensitive techniques to be devoid of perforin. We thus used PMMI activated with PMA and ionomycin, to investigate possible alternate lytic pathways in CTLs in the absence of perforin. We found that PMMI is equipped with membrane TNF-alpha as a potential lytic mechanism, but TNF-alpha is unlikely to be involved in acute (4 h) lytic reactions. On the other hand, PMMI readily lyses target cells expressing the gene for the Fas Ag, but does not lyse target cells expressing fas antisense DNA. The generation of fas-dependent lysis required protein synthesis in PMMI, but target cell protein synthesis was not required for lysis. Lysis of Fas-positive target cells by PMMI was accompanied by DNA fragmentation, and both lysis and DNA fragmentation were blocked by inhibition of protein synthesis in the effector cell. We find the relative extent and kinetics of fas-dependent lysis and DNA fragmentation indistinguishable from that seen in "classical" CTL lytic assays. Both fas- and perforin-dependent lysis were blocked by inhibitors of poly(ADP) ribosylation. We found very little difference in the sequence of events in target cells lysed by the fas pathway compared with the classical (probably perforin) lytic pathway. Given the widespread distribution of fas, particularly in hematopoietic target cells, caution may be required in interpreting the relationship between parameters such as DNA fragmentation and 51Cr-release solely on the basis of the granule exocytosis model.
Secretion of TNF from a rat mast cell line is a brefeldin A-sensitive and a calcium/protein kinase C-regulated process.
Authors: Baumgartner R A , Yamada K , Deramo V A , Beaven M A 
Published: December 2022

Abstract
Stimulated mast cells and cognate cultured cell lines produce and secrete a variety of cytokines including TNF. Because the mechanism by which cytokines are delivered to the external milieu is unknown, the release of TNF was studied in a rat mast cell line (RBL-2H3 cells). In these cells, TNF was not constitutively expressed nor incorporated into secretory granules but was generated de novo upon cell stimulation. It was then released by a process analogous to constitutive secretion in that brefeldin A, an agent known to disrupt Golgi membranes in these cells, inhibited this release without inhibiting release of secretory granules. Unlike constitutive secretion, however, the secretion of TNF was highly regulated by Ca2+ and protein kinase C. Studies with various stimulants and inhibitors indicated that simultaneous mobilization of Ca2+ and activation of protein kinase C were sufficient signals for secretion although optimal production of TNF may be dependent on additional synergistic signals. Because suppression of Ca2+ mobilization or inhibition of protein kinase C alone abrogated TNF secretion, the process may be amenable to therapeutic intervention.
Systemic release and protective role of IL-10 in staphylococcal enterotoxin B-induced shock in mice.
Authors: Florquin S , Amraoui Z , Abramowicz D , Goldman M 
Published: December 2022

Abstract
Staphylococcal enterotoxin B (SEB) is a bacterial superantigen that induces the production of several pro-inflammatory cytokines, leading to a self-limited shock. In the present study, we show that SEB also triggers the systemic release of IL-10, an anti-inflammatory and immunosuppressive cytokine. Serum IL-10 was undetectable (&lt; 1000 pg/ml) in control BALB/c mice and rose to 8500 +/- 2850 pg/ml (mean +/- SEM) 4 h after injection of 100 micrograms SEB. Cell depletion experiments and analysis of IL-10 mRNA expression indicated that CD4+ cells played a major role in SEB-induced IL-10 production. Pretreatment of mice with neutralizing anti-IL-10 mAb before SEB challenge did not modify the release of TNF but led to increased and sustained IL-2 and IFN-gamma serum levels. Furthermore, although no lethality occurred in mice injected with SEB and control mAb, injection of anti-IL-10 mAb before SEB resulted in a 30% lethality (p &lt; 0.05). This lethality was completely prevented by anti-IFN-gamma mAb injection, indicating that IFN-gamma plays a crucial role in the increased toxicity of SEB in anti-IL-10 mAb-injected mice. We conclude that SEB induces the production of IL-10 by CD4+ cells in vivo and that endogenous IL-10 plays an important immunoregulatory role in this model by down-regulating IL-2 and IFN-gamma production.
Eosinophil granule proteins increase microvascular macromolecular transport in the hamster cheek pouch.
Authors: Minnicozzi M , Durán W N , Gleich G J , Egan R W 
Published: December 2022

Abstract
By using microscopic, fluorometric, and immunologic methods, we have assessed the effects of eosinophil granule proteins on the microcirculation of the hamster cheek pouch. The plasma clearance of FITC-dextran 150 (FITC-dx 150) was used to quantify macromolecular transport. Topical application of major basic protein (MaBP) at 0.1 and 0.5 nM increased the clearance of FITC-dx 150 from a base line of 591 to 1283 and 1966 nl/60 min/g, respectively. Numerous muscle fasciculations were also observed with the 0.5 nM dose of MaBP. Eosinophil cationic protein (ECP) was as potent as MaBP and caused an increase in the clearance of FITC-dx 150, 0.5 nM eliciting 2156 nl/60 min/g. In contrast, topical application of 0.5 nM eosinophil peroxidase (EPO) increased clearance of FITC-dx 150 to a significantly lower level, 1113 nl/60 min/g. Supplementing 0.5 nM EPO with 1 nM H2O2 enhanced the clearance of FITC-dx 150 to 2404 nl/60 min/g, suggesting separate cationic charge and enzymatic activity-related effects. Compared with these eosinophil granule proteins, eosinophil-derived neurotoxin (EDN) required a 2000-fold higher concentration (1 microM) to elicit a significant increase in the clearance of FITC-dx 150 (1505 nl/60 min/g). Neither EPO, EPO+H2O2, ECP, nor EDN at 1 mM caused muscle fasciculations. Quantitative analysis of the suffusates from the preparations exposed to these eosinophil proteins did not contain histamine. Our results demonstrate that MaBP, ECP, EPO, and EDN increase microvascular transport in the hamster cheek pouch and that this increase is independent of endogenous histamine release. The concentrations of eosinophil granule proteins causing increased vascular permeability are achieved in many pathologic conditions suggesting that the granule proteins play an important role in disease.
Activation of human monocytes by the pineal hormone melatonin.
Authors: Morrey K M , McLachlan J A , Serkin C D , Bakouche O 
Published: December 2022

Abstract
To determine the effects of the pineal hormone melatonin on human monocytes, human monocytes were activated by different concentrations of melatonin. Above the activation threshold of 5 x 10(-11) M, melatonin was able to induce the cytotoxicity of human monocytes, the secretion of IL-1, and the production of reactive oxygen intermediates. Melatonin and LPS seemed to have a synergistic effect on human monocyte activation. Indeed, below their respective monocyte activation threshold (5 x 10(-11) M and 0.625 ng/ml), melatonin (10(-12) M) in association with LPS (0.2 ng/ml) was able to induce cytotoxicity, IL-1 secretion, and reactive oxygen intermediates production. Melatonin alone at 10(-12) M or LPS alone at 0.2 ng/ml did not activate monocytes. Furthermore, melatonin was able to prime the monocytes for a subsequent activation by LPS. When monocytes were activated by LPS (0.25 ng/ml) at the time that they were plated and then activated by melatonin (10(-12) M) 8 h later, no IL-1 secretion and no cytotoxicity were detected. However, when the cells were first activated by melatonin (10(-12) M), and then 8 h later by LPS (0.25 ng/ml), IL-1 secretion and monocyte cytotoxicity were observed. Above its monocyte activation threshold, melatonin induces both cell-associated IL-1 alpha and IL-1 beta activities. Below this activation threshold, i.e., at 10(-12) M, melatonin does not induce the cell-associated IL-1 alpha and IL-1 beta activities, but does induce the mRNA for both IL-1 (alpha and beta). It seems that melatonin activates monocytes through protein kinase C. These data suggest that melatonin activates monocytes and induces their cytotoxic properties, along with the IL-1 secretion.
The chemokines IL-8, monocyte chemoattractant protein-1, and I-309 are monomers at physiologically relevant concentrations.
Authors: Paolini J F , Willard D , Consler T , Luther M , Krangel M S 
Published: December 2022

Abstract
The chemokines are a family of immune mediators involved in a wide range of inflammatory processes, most importantly as chemoattractants of monocytes, neutrophils, lymphocytes, and fibroblasts to sites of inflammation. Nuclear magnetic resonance and x-ray crystallographic studies have shown that IL-8 and macrophage-inflammatory protein-1 beta (MIP-1 beta) form noncovalent dimers and that platelet factor-4 (PF-4) forms noncovalent dimers and tetramers, leading to the assumption that, as a family, the chemokines would form multimeric structures. In this study, we analyze the association states of the chemokines IL-8, monocyte chemoattractant protein-1 (MCP-1), and I-309, by using a combination of size exclusion HPLC, sedimentation equilibrium ultracentrifugation, and chemical cross-linking. We find that the association states of MCP-1 and IL-8 are characterized by an equilibrium between monomers and dimers: although dimers predominate at concentrations above 100 microM, these chemokines are almost exclusively monomeric at the nanomolar concentrations at which they display maximal chemotactic activity. I-309, by contrast, remains a monomer at all concentrations tested. I-309 contains two additional cysteine residues (C26 and C68) that are not found in any other members of the chemokine family. We used cyanogen bromide and trypsin digestion strategies to demonstrate that these two residues are linked in a unique intramolecular disulfide bond. Furthermore, by using site-directed mutagenesis, we show that the integrity of this bond is crucial for protein secretion.
Potential indirect anti-inflammatory effects of IL-4. Stimulation of human monocytes, macrophages, and endothelial cells by IL-4 increases aminopeptidase-N activity (CD13; EC 3.4.11.2).
Authors: van Hal P T , Hopstaken-Broos J P , Prins A , Favaloro E J , Huijbens R J , Hilvering C , Figdor C G , Hoogsteden H C 
Published: December 2022

Abstract
IL-4 up-regulates various monocytic properties that are associated with pro-inflammatory functions. Paradoxically, IL-4 may also act as an anti-inflammatory agent by down-regulating the production of several inflammatory mediators. As the activity of some mediators has recently been shown to be regulated by peptidases, we examined whether IL-4 was able to modulate the expression of a cell membrane-associated peptidase, aminopeptidase-N (CD13). IL-4 caused a dose-dependent increase in the expression of CD13 Ag on highly purified human blood monocytes. Maximal expression was observed around 48 h of culture. This IL-4-induced increase was completely blocked by anti-IL-4 antiserum. Furthermore, the increase in surface expression was preceded by increased mRNA levels of CD13, which was maximal around 24 h of culture. We also observed that CD13-mediated leucine-aminopeptidase activity of monocytes was induced by IL-4. Other CD13-expressing cells were also sensitive to IL-4, as CD13 Ag expression and CD13 mRNA levels were up-regulated in human alveolar macrophages and endothelial cells upon IL-4 treatment. The increased expression of cell membrane aminopeptidase-N represents a potentially increased cellular ability to inactivate inflammatory mediators. Therefore, these findings represent further evidence of IL-4-mediated anti-inflammatory actions. We postulate that up-regulation of aminopeptidase-N expression may be an indirect mechanism of IL-4 to modulate the action of bioactive peptides. This mechanism may underlie, at least partially, the anti-inflammatory effects of IL-4 in vivo.
Primary biliary cirrhosis. High proportions of B cells in blood and liver tissue produce anti-mitochondrial antibodies of several Ig classes.
Authors: Björkland A , Lööf L , Mendel-Hartvig I , Tötterman T H 
Published: December 2022

Abstract
Anti-mitochondrial Abs (AMA) of the M2 type are recognized as being specific for primary biliary cirrhosis (PBC). We developed a highly specific assay to detect single AMA-producing cells using pyruvate dehydrogenase (PDH), the major Ag for AMA. Total Ab and AMA production of in vivo activated B cells was measured in peripheral blood from 13 PBC patients, 22 patients with other liver diseases, and 15 healthy controls. Anti-PDH-producing cells, PDH spot-forming cells (PDH-SFC), were detected in 12 of 13 PBC patients and represented a very high proportion of circulating Ig-producing lymphocytes (9 +/- 8.6%; mean +/- SD). The autoantibodies were mainly of IgG and IgM Ig classes. The number of PDH-SFC was positively correlated with the numbers of total Ig-SFC within each Ig class. An increased number of total IgM SFC in blood was found in PBC patients compared with controls, and IgM SFC correlated with the elevated serum levels of IgM typical for this disease. Among the lymphocytes extracted from PBC liver tissue (n = 5), we detected PDH-SFC of IgG (range 0 to 33% of total SFC), IgM (0 to 42%), and IgA types (1 to 30%). IgA PDH-SFC were found in five of five livers, but only in two of thirteen blood samples investigated. Taken together, our data reveal that very high numbers of B cells spontaneously produce disease-specific autoantibodies in blood and liver tissue in PBC. Furthermore, the Ig class distribution of produced autoantibody differs between these two compartments, and this may have pathogenetic significance.
Monocyte adhesion in patients with bone marrow fibrosis is required for the production of fibrogenic cytokines. Potential role for interleukin-1 and TGF-beta.
Authors: Rameshwar P , Denny T N , Stein D , Gascón P 
Published: December 2022

Abstract
Idiopathic myelofibrosis (IMF) is a hemologic disorder characterized by bone marrow (BM) fibrosis. The BM contains excessive deposits of extracellular matrix proteins and exhibits neovascularization. The fibrosis is hypothesized to be a reactive phenomenon secondary to a clonal myeloid disorder. Growth factors such as platelet-derived growth factor (PDGF), TGF-beta, and epidermal growth factor have been postulated as potential agents involved in BM fibrosis. We studied the induction of two fibrogenic cytokines, IL-1 and TGF-beta, in IMF monocytes. High levels of both cytokines were produced in unstimulated IMF monocytes, compared with background levels produced in normal controls. Most of the TGF-beta produced by IMF monocytes was in its active form. The spontaneous induction of IL-1 alpha, IL-1 beta, and TGF-beta in IMF monocytes parallels an increase in their steady state mRNA. Although high levels of cytoplasmic IL-1 alpha, IL-1 beta, and TGF-beta protein were detected in monocytes that were not subjected to any form of adherence, the secretion of these cytokines required adhesion. High levels of fibronectin, hyaluronic acid, and collagen, all potential ligands for the CD44 adhesion molecule, have been reported in the circulation of IMF patients. However, the Ab-binding capacity of CD44 in IMF monocytes was reduced by 50% when compared with normal controls. Our results indicate that monocytes and adhesion molecules may play a role in the induction of fibrogenic cytokines. These parameters may be important to the pathophysiology of BM fibrosis.
Subset of CD4+ T cell clones expressing IL-3 receptor alpha-chains uses IL-3 as a cofactor in autocrine growth.
Authors: Mueller D L , Chen Z M , Schwartz R H , Gorman D M , Kennedy M K 
Published: December 2022

Abstract
In this paper we demonstrate that IL-3 can act as a cofactor for the growth of some CD4+ T cells. This lymphokine synergized with IL-4 to induce both a unique set of protein tyrosine phosphorylations and the vigorous proliferation of the keyhole limpet hemocyanin-specific and I-Ab-restricted CD4+ Th0 cell clone, E6. In addition, neutralizing anti-IL-3 Abs specifically inhibited the growth of E6 T cells to Ag or anti-CD3 mAb stimulation. Finally, this T cell clone was shown to express both the IL-3R alpha-chain and an IL-3R beta-chain (AlC2A). An examination of other CD4+ T cell clones determined that one Th1 clone (A.E7), two Th0 clones (16B.2 and L9A.1), and one Th2 clone (D10.G4.1) were not influenced by the addition of rIL-3. However, proliferation of the Th2 clones CDC25 and CDC35 to CD3-stimulation was significantly enhanced by IL-3. The sensitivity of these latter two clones to IL-3 was also found to be associated with expression of IL-3R alpha-chains. Because E6 T cells are highly dependent on IL-4 for autocrine growth similar to Th2 cells, these results suggest that IL-3 may synergize with IL-4 to enhance the proliferation of a subset of IL-4-dependent CD4+ T cells, and the study indicates that IL-3R alpha-chain expression may be a specific marker of this CD4+ T cell subset.