bluuebunny/crossref_metadata_2025_split huggingface dataset:
Induction of procoagulant function in porcine endothelial cells by human natural killer cells.
Authors: Malyguine A M , Saadi S , Holzknecht R A , Patte C P , Sud N , Platt J L , Dawson J R 
Published: December 2022

Abstract
NK cells may mediate effector functions other than target cell cytotoxicity. To explore such noncytotoxic effector mechanisms, we tested whether human PBL and purified NK (CD56+) cells might induce expression of tissue factor by cultured porcine aortic endothelial cells. Tissue factor is the major coagulation factor that binds to factor VIIa and initiates coagulation. The addition of freshly isolated NK cells but not T cells to endothelial cells resulted in the induction of tissue factor activity. NK-depleted (CD56-) effector cells did not induce tissue factor activity; however, the combination of CD56+ cells and NK-depleted cells induced tissue factor activity to the same extent as unseparated cells. PBL induced tissue factor mRNA in porcine endothelial cells and NK depletion resulted in a significant decrease of the induction. Induction of tissue factor activity in porcine endothelial cells by human NK cells required direct cell-to-cell contact, as transfer of supernatants from NK-endothelial cell cultures to secondary cultures did not induce tissue factor activity, and anti-LFA-1alpha Abs inhibited the induction of tissue factor activity. Induction of tissue factor activity in endothelial cells by NK cells may represent one of a variety of ways in which NK cells mediate noncytotoxic effects.
Natural processing sites for human cathepsin E and cathepsin D in tetanus toxin: implications for T cell epitope generation.
Authors: Hewitt E W , Treumann A , Morrice N , Tatnell P J , Kay J , Watts C 
Published: December 2022

Abstract
Cathepsin E is an aspartic proteinase that has been implicated frequently in Ag processing for presentation on class II MHC molecules, but no information exists on its cleavage specificity within Ags in relation to known T cell epitopes. We have analyzed the processing by cathepsin E of a large C-terminal domain of tetanus toxin (residues 872-1315), and we have compared the processing products with those liberated by cathepsin D, a related aspartic proteinase also thought to be involved in class II MHC-restricted Ag processing. Processing products were analyzed by N-terminal Edman degradation and mass spectrometry following reverse-phase HPLC separation of peptides. A total of 28 cleavage sites was identified, 11 of which were recognized by both cathepsins E and D. Most, although not all, sites were between pairs of hydrophobic residues and were located within the 200-amino-acid C terminal region known to contain several human T cell epitopes. Previously described T cell epitopes, for example, between residues 1273 and 1284, were flanked by cathepsin E and D cleavage sites. These data are consistent with an important role for cathepsins E and/or D in Ag processing in the human immune system.
Constitutive activation of JAKs and STATs in BCR-Abl-expressing cell lines and peripheral blood cells derived from leukemic patients.
Authors: Chai S K , Nichols G L , Rothman P 
Published: December 2022

Abstract
An important step in the oncogenic transformation of hemopoietic cells and the subsequent development of leukemia is the proliferation of tumor cells in the absence of exogenous growth factors. In most cases of chronic myelocytic leukemia and in some cases of acute myelocytic leukemia and acute lymphocytic leukemia, the bcr-abl oncogene is involved in this process. Although the BCR-Abl oncoprotein demonstrates enhanced tyrosine kinase activity in leukemic cells, the mechanism by which this leads to growth factor independence remains poorly defined. One proposed mechanism is the activation of cytokine signal transduction pathways, possibly by an autocrine loop involving IL-3 and/or granulocyte-macrophage CSF. Examination of several different cell lines expressing BCR-Abl demonstrates that some of these cells have constitutive activation of the JAK/STAT signaling pathway. We have found the constitutive activation of STAT5 in most, but not all, cell lines expressing BCR-Abl. This constitutive activation of STAT5 is variably associated with a corresponding activation of JAK kinases. Ab blocking studies show that the activation of STAT5 in these cell lines cannot be attributed to the activation of an IL-3/granulocyte-macrophage CSF-driven autocrine loop. Interestingly, samples of peripheral blood cells derived from patients with acute myelocytic leukemia and chronic myelocytic leukemia, which express BCR-Abl, demonstrate constitutive activation of STAT family members. These studies suggest that in a variety of leukemic states, BCR-Abl may use a bypass mechanism to activate cytokine signal transduction pathways.
Pivotal role of endogenous TNF-alpha in the induction of functional inactivation and apoptosis in NK cells.
Authors: Jewett A , Cavalcanti M , Bonavida B 
Published: December 2022

Abstract
The interaction of purified nonactivated human NK cells with target cells overnight results in functional anergy and apoptosis in NK cells and in a change of the NK phenotype from CD16+ CD56+ CD69- to CD16(dim/-) CD56(+/dim/-) CD69+. These studies suggested that signaling triggered by the FcR CD16 may be implicated in target cell-mediated anergy/apoptosis of NK cells. We hypothesized that triggering CD16 by anti-CD16 Ab should result in NK cells exhibiting functional and phenotypic properties similar to those obtained following triggering of NK cells with target cells. The findings demonstrate that the anti-CD16 mAb-treated NK cells acquired the CD16- CD56(+/dim) CD69+ Fas+ phenotype and lost their cytotoxic function, a significant number of the NK cells underwent apoptosis, and a selective induction of TNF-alpha synthesis and secretion was observed. The coaddition of IL-2 to anti-CD16 Ab-treated NK cells resulted in enhanced secretion of TNF-alpha and augmentation of the frequency of cell death. However, a minor subset of NK cells exhibited potent cytotoxic function and proliferated. The anti-CD16-induced effects in NK cells were largely abrogated by the addition of either anti-TNF-alpha Ab or TNF-binding protein in the cultures. There was an enhancement of NK cell killing following the addition of exogenous TNF-alpha into the culture. Cytochalasin B selectively triggered the secretion of TNF-alpha and significantly augmented the frequency of apoptosis of anti-CD16-treated NK cells. These findings demonstrate an important and pivotal role of endogenous TNF-alpha synthesis and secretion by NK cells in the induction of functional anergy and apoptosis in anti-CD16-treated NK cells.
Naturally occurring A pocket polymorphism in HLA-B*2703 increases the dependence on an accessory anchor residue at P1 for optimal binding of nonamer peptides.
Authors: Griffin T A , Yuan J , Friede T , Stevanovic S , Ariyoshi K , Rowland-Jones S L , Rammensee H G , Colbert R A 
Published: December 2022

Abstract
Previous studies have shown the B*2703 subtype of HLA-B27, which differs from B*2705 and other MHC class I molecules by having a His substituted for Tyr at position 59 in the A pocket, inefficiently presents certain B*2705-restricted peptides. The current work investigates the influence of the first peptidic amino acid (P1) on peptide binding to B*2705 and B*2703. Results show P1 has a marked effect for both subtypes, with relative affinities (EC50) of P1-substituted peptides spanning four orders of magnitude. All peptides tested bind better to B*2705 than to B*2703. However, Lys, Arg, Phe, or Trp at P1 result in a &lt; or = 2-fold difference between subtypes, while other amino acids produce greater differences (maximum approximately 50-fold for Leu). Self peptides eluted from B*2703, as well as two viral epitopes, have a motif similar to B*2705 peptides, except for a stronger preference for Lys or Arg at P1, consistent with peptide binding data. Computer modeling of B*2703 reveals movement of a water molecule and the alpha1 alpha-helix to allow His at position 59 to maintain important hydrogen bonds with the peptide N terminus in the A pocket. However, these bonds are weaker, and the water molecule movement results in the loss of a hydrogen bond with Glu-45 in the B pocket. We conclude that B*2703, as a consequence of its unique A pocket polymorphism, appears to have a greater dependency on an accessory anchor residue at P1 to maintain tight binding of peptides.
Enhancement of natural killer cell cytotoxicity by the human herpesvirus-7 via IL-15 induction.
Authors: Atedzoe B N , Ahmad A , Menezes J 
Published: December 2022

Abstract
NK cells, a key component of the innate immune system, are known to play an important role against viral infections. Previously, we reported that the human herpesvirus-6 (HHV-6) induces IL-15 in human PBMC and increases their NK activity. We describe in this work that another human herpesvirus, HHV-7, which shares genomic homology with HHV-6, also causes up-regulation of NK cell cytotoxicity via IL-15 induction. The NK cell activity of the PBMC from different donors displayed a variable range of enhancement after treatment with HHV-7. This enhancement occurred within a few hours of exposure to the virus and was blocked by Abs to IL-15, but not to other cytotoxicity-enhancing cytokines (i.e., to IFN-gamma, IL-2, TNF-alpha, or IL-12). Our results also show that this HHV-7-induced IL-15-mediated activation of NK cells occurs via IL-2R, since HHV-7-enhanced NK cytotoxic activity could be blocked completely by anti-IL-2R beta-chain mAb (anti-CD122). The up-regulation of NK cell cytotoxicity did not require infectious virus, as the use of UV-irradiated HHV-7 produced similar results. This effect was virus specific because it was abrogated by neutralizing the virus with human sera containing Abs to HHV-7. We also found increased amount of IL-15 transcripts in HHV-7-treated PBMC as compared with the untreated PBMC. Taken together, these results would suggest that host responds to HHV-7 infection by up-regulating IL-15 production, which then results in an enhancement of NK cell activity; this, in turn, may play a major role in the control of the viral infection.
Alteration of macrophage function by a Trypanosoma cruzi membrane mucin.
Authors: de Diego J , Punzón C , Duarte M , Fresno M 
Published: December 2022

Abstract
Cytokines secreted by macrophages play important roles in the immune response to Trypanosoma cruzi. Here, we report that a purified glycosylphosphatidylinositol (GPI)-anchored mucin from the T. cruzi membrane, Ag C10, is able to bind to the macrophage cell surface and blocks the subsequent binding of mAb against CD62L/L-selectin, whereas binding of mAbs directed against other monocyte surface molecules is unaffected. In addition, Ag C10 binding to macrophages triggered a CD54/ICAM-1-mediated cell adhesion as well as an increase in intracellular Ca2+, which was further augmented by cross-linking the Ag C10-bound surface receptors by mAb against Ag C10. Interestingly, Ag C10-treated monocytes secreted IL-1beta, but not TNF-alpha or IL-12. Moreover, these cells could secrete IL-1beta, but not TNF-alpha or IL-12, after activation with LPS. T. cruzi-infected macrophages displayed similar alterations in cytokine secretion, with an impaired ability to secrete IL-12 and TNF-alpha, but not IL-1beta, upon LPS activation. These effects were substantially inhibited by neutralizing mAb against Ag C10. These effects appeared to take place at the transcriptional level, since mRNA for TNF-alpha, but not that for IL-1beta, was drastically reduced in LPS-stimulated infected cells treated with Ag C10. Conceivably, inhibition of TNF-alpha and IL-12 by T. cruzi could be involved in the evasion of the immune response by this parasite.
Analysis of granuloma formation in double cytokine-deficient mice reveals a central role for IL-10 in polarizing both T helper cell 1- and T helper cell 2-type cytokine responses in vivo.
Authors: Wynn T A , Morawetz R , Scharton-Kersten T , Hieny S , Morse H C , Kühn R , Müller W , Cheever A W , Sher A 
Published: December 2022

Abstract
In response to i.v.-injected eggs of Schistosoma mansoni, normal mice develop a dominant type 2 response, whereas IL-10-deficient animals generate a mixed type 1/type 2 cytokine profile and show reduced pulmonary granuloma formation. IL-4-deficient mice, while displaying diminished type 2 responses and granulomatous inflammation, also do not fully default to a type 1 cytokine profile. Strikingly, mice doubly deficient in IL-4 and IL-10 are completely defective in pulmonary granuloma formation and develop a highly polarized type 1 cytokine pattern. In analogous fashion, mice deficient in both IL-12 and IL-10 generate highly exacerbated type 2 cytokine responses, whereas in wild-type animals, IL-12 depletion minimally effects egg-induced cytokine production. Together, these results argue first that IL-10 is an important endogenous down-regulator of type 2 as well as type 1 cytokine synthesis, and second, that its induction is critical for type 2 response polarization in vivo.
CD8+ T cells clear influenza virus by perforin or Fas-dependent processes.
Authors: Topham D J , Tripp R A , Doherty P C 
Published: December 2022

Abstract
Influenza virus infection is controlled in CD4-depleted mice that are also defective for the expression of either Fas (Fas-/-) or perforin (P-/-). Virus-immune P+/+ and P-/- CD8+ T cells can thus function in, respectively, a Fas-/- or Fas+/+ lung environment. The obvious question is whether the P-/- CD8+ set is effective in Fas-/- mice, a conclusion that would tend to favor cytokine secretion as the mode of virus clearance. Short term chimeras were made with P-/- bone marrow, P+/+ or P-/- T cells, and Fas+/+ or Fas-/- irradiated recipients. While the P+/+ CD8+ population cleared the virus from Fas+/+ and Fas-/- respiratory epithelium, the P-/- effectors were operational only if there was the potential for Fas to be expressed on radiation-resistant lung cells. Target cell destruction mediated via the Fas or perforin pathways is clearly the primary mechanism used by CD8+ T cells to terminate this viral pneumonia.
The basis for self-tolerance of natural killer cells in beta2-microglobulin- and TAP-1- mice.
Authors: Dorfman J R , Zerrahn J , Coles M C , Raulet D H 
Published: December 2022

Abstract
Cells from mice with mutations in the genes for beta2-microglobulin (beta2m) or for TAP-1 express only low levels of MHC class I proteins on their surfaces, and are thus sensitive to attack by normal NK cells. Although NK cells are present in beta2m- mice and TAP-1(-) mice, they are completely self-tolerant. The underlying mechanism for this tolerance is unknown. It has been proposed that education processes render NK cells from these mice hypersensitive to class I-mediated inhibition, so that they can be inhibited even by the low levels of class I expressed on autologous cells. In this study, we present evidence against this hypothesis, by demonstrating that NK cells from beta2m- mice and TAP-1(-) mice fail to attack beta2m(-)TAP-1(-) double-mutant cells in both in vitro and in vivo assays. The latter cells express substantially lower levels of class I than single-mutant cells, based on serologic tests, as well as a significantly diminished sensitivity to attack by class I-specific CTL. Furthermore, the Ly-49 repertoire on NK cells derived from beta2m(-)TAP-1(-) mice is highly similar to that of either single mutant, indicating that the developmental processes that shape the Ly-49 repertoire cannot respond to the differences in class I levels among these mice. We propose that self-tolerance of NK cells in beta2m- mice and TAP-1(-) mice is likely to result from hyporesponsiveness of the cells to activating signals, or alternatively, to induction of inhibitory signaling through receptors specific for non-class I MHC ligands.
Protein-tyrosine phosphorylation by IgG1 subclass CD38 monoclonal antibodies is mediated through stimulation of the FcgammaII receptors in human myeloid cell lines.
Authors: Inoue S , Kontani K , Tsujimoto N , Kanda Y , Hosoda N , Hoshino S , Hazeki O , Katada T 
Published: December 2022

Abstract
The human surface Ag CD38 is a 46-kDa type II transmembrane glycoprotein, and its expression is dependent on the cell differentiation and activation of lymphocytes. Our previous work in human myeloid cells showed that ligation of CD38 with mAbs (HB-7 and T-16; IgG1 subclass) not only induced protein-tyrosine phosphorylation but also potentiated superoxide generation stimulated by G protein-coupled receptors. In the present study we analyzed the mechanisms of action of the agonistic mAbs. HB-7-induced tyrosine phosphorylation could be still observed in human myeloid cells expressing CD38 mutants, of which cytoplasmic and transmembrane domains had been deleted or replaced by those of another type II glycoprotein (PC-1). Moreover, N-linked glycosylation on the cell surface CD38 was not required for the HB-7-induced cell signaling. The profile of tyrosine-phosphorylated proteins by HB-7 was exactly the same as that induced by cross-linking of FcgammaII receptors (FcgammaRII/CD32), and FcgammaRII itself was tyrosine phosphorylated in the two stimulated cells. The HB-7-induced tyrosine phosphorylation was completely abolished after masking of FcgammaRII with its mAb. Finally, F(ab')2 of HB-7 failed to mimic the actions of the whole form of mAb. These results indicate that anti-CD38 mAb-induced tyrosine phosphorylation and its associated cell response are entirely mediated through the FcgammaRII-induced signaling pathway, possibly resulting from stimulation of the cell surface human FcgammaRII with the mouse Fc region (IgG1 subclass) of CD38-ligated mAbs.
Acquisition of granzyme B and Fas ligand proteins by human keratinocytes contributes to epidermal cell defense.
Authors: Berthou C , Michel L , Soulié A , Jean-Louis F , Flageul B , Dubertret L , Sigaux F , Zhang Y , Sasportes M 
Published: December 2022

Abstract
In vertebrate tissues, cell integrity is maintained by at least three mechanisms. During an immune response, injured cells are eliminated by cytotoxic lymphoid cells that produce perforin, granzyme B, and Fas ligand (FasL). Second, epithelial cells can produce FasL as an immunosuppressive protein, probably to protect the tissue against immune-mediated damage. Third, locally secreted antimicrobial peptides can be operative in the protection of animal and human epithelia. In this work, as another contribution to local mechanisms of host defense, the ability of human epidermal keratinocytes to produce cytotoxic proteins was investigated. To address this question, freshly isolated human epidermal cells and keratinocytes grown in vitro were studied. Freshly isolated epidermal cells did not express the cytolytic proteins. In contrast, keratinocyte growth to confluence was associated with granzyme B, perforin, and FasL mRNA and protein synthesis. These proteins were secreted in the culture medium. Further analysis showed that they were identical with the ones used by cytotoxic lymphocytes. Their function was then investigated with a view to a potential role in epidermal cell integrity. The data showed that activated human keratinocytes were able to protect against invading pathogens through granzyme B expression. This was demonstrated by the ability of granzyme B to greatly decrease the bacterial growth of Staphylococcus epidermidis. In addition, keratinocytes expressing FasL were found to prevent immune epidermal cell damage. Apoptosis of Fas-sensitive T cells occurred during coculture with confluent epidermal keratinocytes and was largely reduced by the addition of a FasL inhibitor. The data favor keratinocyte involvement in the regulation of dermal inflammatory responses.
Natural variants of the immunodominant HLA A11-restricted CTL epitope of the EBV nuclear antigen-4 are nonimmunogenic due to intracellular dissociation from MHC class I:peptide complexes.
Authors: Levitsky V , Zhang Q J , Levitskaya J , Kurilla M G , Masucci M G 
Published: December 2022

Abstract
EBV isolates from human populations with a high frequency of HLA A11 evade recognition by CTLs specific for an immunodominant A11-restricted epitope derived from the EBV nuclear antigen 4 (EBNA-4). We have previously described four nonimmunogenic variants of this epitope carrying single amino acid substitutions in the anchor residues of the peptide. We have now investigated the antigenicity, A11 binding capacity, endoplasmic reticulum translocation, endogenous processing, and presentation of these variants. The nonimmunogenic peptides were either unable to bind to HLA A11 or formed complexes of significantly lower stability compared with the immunogenic epitope. The latter peptides were produced in relatively large amounts by endogenous processing of EBNA-4 and associated with A11 molecules almost as efficiently as the immunogenic epitope, but the complexes failed to accumulate at the cell surface. The defect was not reversed by incubation of lymphoblastoid cell lines carrying the variant EBV strains at 26 degrees C. CTL lysis of HLA A11 positive targets was achieved by expressing one of the nonimmunogenic peptides through a vaccinia recombinant. However, the amount of peptide required for CTL sensitization exceeded, by at least 30-fold, that required for recognition of the immunogenic epitope. Collectively, these results suggest that complexes containing the nonimmunogenic peptides are formed but are then destroyed intracellularly. Thus, a specialized sorting mechanism seems to contribute in shaping the repertoire of peptides presented to T lymphocytes.
Delta-opioid receptors expressed by Jurkat T cells enhance IL-2 secretion by increasing AP-1 complexes and activity of the NF-AT/AP-1-binding promoter element.
Authors: Hedin K E , Bell M P , Kalli K R , Huntoon C J , Sharp B M , McKean D J 
Published: December 2022

Abstract
Recent molecular evidence points to transient and/or stage-specific expression of delta- and kappa-opioid receptors by thymic and peripheral T lymphocytes. Since medical treatments or stress commonly increase opioid levels, it is important to understand the mechanisms by which opioids affect T lymphocyte functions. We therefore created and studied a T cell line expressing the cloned delta-opioid receptor (DOR1). DOR1 ligation by a specific DOR1 agonist, deltorphin, augmented IL-2 secretion by synergizing with signals from TCR-CD3 and CD28. Reporter gene constructs were used to map this effect of deltorphin to the AP-1- and NF-AT/AP-1-binding sites of the IL-2 promoter. Although DOR1 signaling increased [Ca2+]i, deltorphin enhanced transcriptional activity of the NF-AT/AP-1-binding site via a mechanism independent of calcineurin and distinct from the effects of elevated [Ca2+]i. Deltorphin also increased accumulation of AP-1 transcription factor complexes, suggesting that DOR1 augments IL-2 secretion by increasing the AP-1 component of the NF-AT/AP-1 transcription factor. These results advance the molecular understanding of opioid effects on lymphocytes, and in addition, demonstrate regulation of IL-2 synthesis and secretion by the novel mechanism of receptor-mediated AP-1 induction.