bluuebunny/crossref_metadata_2025_split huggingface dataset:
Class I-deficient hemopoietic cells and nonhemopoietic cells dominantly induce unresponsiveness of natural killer cells to class I-deficient bone marrow cell grafts.
Authors: Wu M F , Raulet D H 
Published: December 2022

Abstract
NK cells in normal mice reject bone marrow transplants from class I-deficient mice. In contrast, class I-deficient mice do not reject autologous cells, suggesting that NK cell tolerance is acquired. We employed fetal liver irradiation chimeras to assess two potential mechanisms that could account for the tolerance of NK cells in class I-deficient mice to class I-deficient cells: 1) a positive model, in which recognition of class I+ cells molecules by NK cells is necessary to induce functional NK cell maturation; and 2) a negative model, in which interactions of NK cells with class I-deficient cells induce tolerance. In class I+ chimeras reconstituted with mixtures of class I+ and class I-deficient fetal liver cells, the rejection of class I-deficient bone marrow cell grafts was significantly impaired, supporting the negative model. We further addressed whether nonhemopoietic cells are also able to induce NK cell tolerance. Class I- mice reconstituted with class I+ fetal liver cells were tolerant of class I-deficient cells, favoring this idea. Furthermore, class I-deficient mice reconstituted with a mixture of class I-deficient and class I+ fetal liver cells were more tolerant to class I-deficient cells than were class I+ mice reconstituted with the same fetal liver cell mixture. These results suggest that maximal tolerance induction requires the presence of class I-deficient nonhemopoietic cells.
T cell priming against vesicular stomatitis virus analyzed in situ: red pulp macrophages, but neither marginal metallophilic nor marginal zone macrophages, are required for priming CD4+ and CD8+ T cells.
Authors: Ciavarra R P , Buhrer K , Van Rooijen N , Tedeschi B 
Published: December 2022

Abstract
Since extensive degradation may be required to present complex Ags, we addressed whether macrophages (M phi) might function as APC for anti-viral cell-mediated immune responses. To study this question, murine splenic M phi were depleted by i.p. administration of liposome-encapsulated dichloromethylene diphosphonate (Cl2MDP-liposomes or clodronate-liposomes) before priming mice with vesicular stomatitis virus (VSV). Cl2MDP-liposome treatment resulted in the rapid (1-day) depletion of splenic M phi that was associated with a suppression of the ability of M phi-deficient mice to generate secondary anti-VSV CTL and Th cell proliferative responses in vitro. Control studies demonstrated that splenic dendritic cells were not adversely affected by treatment with Cl2MDP-liposomes. To assess the contribution of splenic M phi subpopulations to T cell priming against this virus, priming was delayed following treatment with Cl2MDP-liposomes until specific M phi subsets had repopulated the spleen. This analysis revealed that repopulation by red pulp M phi, but not with other splenic M phi subsets, was associated with the ability to mount normal secondary CTL and Th cell responses against VSV. Depletion of splenic, but not resident, peritoneal M phi by i.v. injection of Cl2MDP-liposomes did not rescue T cell priming in VSV-infected mice. Thus, only red pulp M phi, and not other splenic or peritoneal M phi populations, are necessary for T cell priming to VSV, a biochemically complex Ag.
Activation of the lymphotoxin beta receptor by cross-linking induces chemokine production and growth arrest in A375 melanoma cells.
Authors: Degli-Esposti M A , Davis-Smith T , Din W S , Smolak P J , Goodwin R G , Smith C A 
Published: December 2022

Abstract
The lymphotoxin beta receptor (LT beta R) was originally described as a transcribed sequence encoded on human chromosome 12p, with homology to the TNF receptor family. Subsequently, a recombinant LT beta R was shown to bind LT alpha LT beta heteromeric complexes. In this study, we have shown that LT beta R is expressed in a variety of tissues and cell lines of monocytic lineage, as well as in fibroblast and human melanoma cell lines. Unlike other members of the TNF receptor family, LT beta R is not expressed by peripheral blood T cells. A chimeric fusion protein consisting of the extracellular domain of LT beta R fused to the Fc region of human IgG1 was used to develop mAbs against LT beta R. Cross-linking LT beta R on A375 melanoma cells with these Abs generated an antiproliferative signal. In addition, the IL-8 and RANTES chemokines, early indicators of inflammation, were secreted by the A375 melanoma line and the WI38VA13 fibroblast line in response to cross-linking of LT beta R. These same activities could be induced by membrane-bound and soluble LT beta and LT alpha LT beta oligomers.
Mechanism of complement inactivation by glycoprotein C of herpes simplex virus.
Authors: Kostavasili I , Sahu A , Friedman H M , Eisenberg R J , Cohen G H , Lambris J D 
Published: December 2022

Abstract
Glycoprotein C (gC) of both herpes simplex virus type 1 (HSV-1) and HSV-2 interacts with complement C3b and protects the virus from complement-mediated neutralization. To study the mechanism by which gC modulates complement activation, we expressed both gC-1 and gC-2 in a baculovirus expression system. Baculovirus recombinants containing gC genes spanning the entire gC-1 sequence (gC-1-TMR) or only the extracellular domain(s) of gC-1, gC-2, or a deletion mutant of gC-1 lacking residues 33 through 123 were expressed in sf9 insect cells. Binding of the expressed proteins to human C3 and C3 fragments was assessed by direct and competition ELISA. All four expressed proteins bound to C3, C3b, and C3c but not to C3d, suggesting 1) that the binding sites for these proteins are located in the C3c region of C3; and 2) that gC, in contrast to other C3-binding proteins, interacts with native C3. We have also examined the interaction of native C3 with gC-1 expressed on the HSV-1-infected cells. Analogous to recombinant proteins, gC-1 expressed on the infected cells also bound to native C3. The ability of baculovirus-expressed gCs to inhibit the interaction of C3b with its ligands was also analyzed. We found that gC-1, but not gC-2, inhibited the binding of C5 and properdin to C3b and also inhibited the alternative pathway-mediated lysis of rabbit erythrocytes. Inhibition of alternative pathway-mediated lysis and properdin binding to C3b, but not of C5 binding to C3b, required the transmembrane segment of the gC-1. The specificity of gC interactions was examined by studying the interaction of gC with C3 from various species. In contrast to properdin, both gCs bound to cobra C3; this finding suggests that gC-1 and properdin bind to different sites on C3b. Further analyses suggested that gC-1 sterically hindered access of C5 and properdin to C3b.
Expression of lung inducible nitric oxide synthase protein does not correlate with nitric oxide production in vivo in a pulmonary immune response against Cryptococcus neoformans.
Authors: Lovchik J , Lipscomb M , Lyons C R 
Published: December 2022

Abstract
Mice infected intratracheally with Cryptococcus neoformans (Cne) require CD4 and CD8 T cells, IFN-gamma, and M phi production of nitric oxide (NO) for effective resolution of the pulmonary infection. Differences exist among strains of mice in clearing the infection. C.B-17 mice reduced Cne lung burden at a significantly greater rate than C57BL/6 (B6) mice and resistance correlated with greater IFN-gamma production by C.B-17 lung-associated lymph node cells. We examined whether the differences observed in the ability of B6 vs C.B-17 mice to clear Cne was due to 1) numbers of inflammatory cells recruited to the lung, 2) the activation state of the recruited cells as measured by expression of inducible nitric oxide synthase (iNOS), and/or 3) the in vivo production of NO as measured by quantitating urine nitrates. The level of iNOS protein was identical in lungs from both strains of mice during Cne infection as determined by Western blot analysis of whole lung homogenates and immunocytochemistry of isolated lung macrophages. Surprisingly, in vivo studies of iNOS activity indicated that NO production in B6 mice was significantly less than that in C.B-17 mice. While single cell suspensions from lungs of either mouse strain produced identical amounts of NO, NO production by lung explants paralleled in vivo urinary nitrate excretion, suggesting that the maintenance of pulmonary architecture and cell-cell interaction was necessary for suppression of iNOS activity in B6 mice. These data strongly implicate the existence of mechanisms that regulate NO production at the level of enzyme activity during infections and have important implications for analyzing the role of iNOS during an immune response in in vivo models.
Protective monoclonal antibody defines a circumsporozoite-like glycoprotein exoantigen of Cryptosporidium parvum sporozoites and merozoites.
Authors: Riggs M W , Stone A L , Yount P A , Langer R C , Arrowood M J , Bentley D L 
Published: December 2022

Abstract
The apicomplexan protozoan parasite Cryptosporidium parvum causes a diarrheal disease in humans and other mammals for which specific therapy and immunoprophylaxis are unavailable. Passive immunization with Abs against whole C. parvum organisms has variable efficacy in immunocompromised or neonatal hosts. Because apical and surface-exposed zoite Ags of the Apicomplexa are critical to infectivity and targets of protective immunity, we examined the ability of mAbs generated against such Ags in C. parvum sporozoites to passively protect against infection and identify biologically relevant parasite molecules. A panel of mAbs was produced against affinity-purified native Ags using sporozoite apical- and surface-reactive mAb C4A1 as binding ligand. One resulting mAb, designated 3E2, elicited prominent morphologic changes in sporozoites and merozoites characterized by rapid and progressive formation, posterior movement, and release of membranous Ag-mAb precipitates. These changes had a striking resemblance to the malarial circumsporozoite precipitate (CSP) reaction. Sporozoite infectivity was completely neutralized after in vitro exposure to 3E2 and the CSP-like reaction. Furthermore, orally administered 3E2 completely prevented or markedly reduced infection in neonatal BALB/c mice. 3E2 bound to apical complex and surface molecules of zoites and was demonstrated in membranous precipitates by immunoelectron microscopy. In Western blots, 3E2 recognized multiple 46 to approximately 770 kDa sporozoite Ags and an approximately 1300-kDa Ag designated CSL, also expressed by merozoites. CSL was characterized as a soluble glycoprotein exoantigen released by infectious sporozoites. Further, CSL was determined to be the molecular species mechanistically involved in the CSP-like reaction by its identification in SDS-PAGE gels and Western blots of purified membranous precipitates. These findings indicate that CSL has a functional role in sporozoite infectivity and is a candidate molecular target for passive or active immunization against cryptosporidiosis.
Identification of subdominant CTL epitopes of the GP100 melanoma-associated tumor antigen by primary in vitro immunization with peptide-pulsed dendritic cells.
Authors: Tsai V , Southwood S , Sidney J , Sakaguchi K , Kawakami Y , Appella E , Sette A , Celis E 
Published: December 2022

Abstract
The gp100 melanoma-associated tumor Ag was selected as a model system to study the diversity of human antitumor cytotoxic T cell responses. First, peptides corresponding to dominant gp100 HLA-A2.1-restricted CTL epitopes were tested using lymphocytes from normal volunteers and an in vitro priming protocol that uses peptide-pulsed dendritic cells as APCs and IL-7 and IL-10 as immune-enhancing cytokines. High CTL activity toward both peptide-pulsed target cells and gp100+ melanoma cells was obtained with four out of five peptides tested. Second, HLA-A2.1-binding peptides from gp100 that do not appear to represent CTL epitopes in melanoma patients were also tested for their capacity to induce CTL using the in vitro priming protocol. Three of six peptides tested induced CTL in lymphocytes from normal volunteers. One of these peptides was also immunogenic for lymphocytes derived from a melanoma patient in remission. Because these three CTL epitopes were not recognized in the natural immune response in melanoma patients but do appear as immunogens when peptides are used to induce the T cell response, they may be considered as typical "subdominant" epitopes. The results are discussed in the context of the usefulness of this approach to detail the immunologic potential of a given tumor-associated Ag and its relevance for the design of effective immune-based therapies.
Phosphatidyl serine is involved in the reduced rate of transcription of the inducible nitric oxide synthase gene in macrophages from tumor-bearing mice.
Authors: DiNapoli M R , Calderon C L , Lopez D M 
Published: December 2022

Abstract
Upon stimulation with LPS, peritoneal-elicited macrophages (PEM) from mammary tumor-bearing mice display a diminished ability to produce nitric oxide (NO) and lyse tumor targets. In contrast, when these cells are stimulated with LPS in combination with IFN-gamma, they perform these functions at normal levels. Kinetic studies revealed that these defects became more pronounced with tumor progression and were accompanied by similar changes in inducible nitric oxide synthase (iNOS) mRNA levels. Since this tumor is known to produce PGE2, granulocyte-macrophage CSF (GM-CSF), and phosphatidyl serine, we evaluated the effects of these products on NO production and cytolytic activity. Pretreatment of normal PEM with PGE2 or recombinant GM-CSF had negligible effects on NO production and cytolytic capacity. In contrast, phosphatidyl serine caused a concentration-dependent inhibition of these functions in response to LPS, which could be partially overcome by the addition of IFN-gamma. Moreover, iNOS mRNA levels paralleled these changes and were analogous to the alterations observed in the tumor-bearers' PEM. iNOS mRNA stability was not reduced in these cells; however, the rate of transcription was diminished relative to normal levels, suggesting that the defects causing these alterations are occurring at or before the level of iNOS transcription. These data implicate tumor-derived phosphatidyl serine in the alterations observed in tumor-bearers' macrophages and suggest that reduced iNOS transcription is responsible for the diminished capacity of these macrophages to produce NO and lyse tumor targets.
Stimulation of macrophages by lipopolysaccharide alters the phosphorylation state, conformation, and function of PU.1 via activation of casein kinase II.
Authors: Lodie T A , Savedra R , Golenbock D T , Van Beveren C P , Maki R A , Fenton M J 
Published: December 2022

Abstract
We previously reported that LPS stimulation of the RAW264.7 murine macrophage cell line rapidly induced a structural change within the N terminus of the transcriptional regulatory factor PU.1. PU.1 is required for the expression of a variety of cytokine, cytokine receptor, and integrin genes. Western blot analysis of nuclear extracts prepared from LPS-stimulated macrophages revealed increased phosphorylation of PU.1 at serine residues relative to that in unstimulated controls. PU.1-DNA complexes prepared using nuclear extracts from LPS-stimulated macrophages were less sensitive to protease digestion compared with PU.1-DNA complexes generated using nuclear extracts prepared from unstimulated cells. This altered protease sensitivity probably reflects a conformational change within PU.1 resulting from LPS-induced phosphorylation. This possibility was supported by the finding that in vitro-phosphorylated PU.1 was similarly resistant to protease digestion. Transient transfection studies suggest that LPS-induced phosphorylation of PU.1 at serine 148, located within a casein kinase II (CKII) consensus motif, increases the transactivation function of PU.1. Other serine/CKII sites located at positions 41, 45, 132, and 133 do not appear to be required for LPS-induced PU.1 function. Lastly, we found that LPS also increased the enzymatic activity of CKII in these cells. To our knowledge, these are the first studies to demonstrate that LPS can stimulate CKII activity, induce PU.1 phosphorylation, and enhance the capacity of PU.1 to activate transcription in macrophages.
Studies on the interaction of IL-8 with human plasma alpha 2-macroglobulin: evidence for the presence of IL-8 complexed to alpha 2-macroglobulin in lung fluids of patients with adult respiratory distress syndrome.
Authors: Kurdowska A , Carr F K , Stevens M D , Baughman R P , Martin T R 
Published: December 2022

Abstract
alpha 2-Macroglobulin (alpha 2m) is a major plasma proteinase inhibitor, as well as a carrier and regulator of the function of many cytokines. IL-8 is a potent neutrophil attractant and activator, and it plays an important role in the pathogenesis of adult respiratory distress syndrome (ARDS). The concentration of both IL-8 and alpha 2m is increased in lung fluids from patients with ARDS. Therefore, interaction of IL-8 with human alpha 2m was studied. Mixtures of native and methylamine-treated alpha 2m (fast alpha 2m) with 125I-labeled IL-8 were analyzed using nonreducing gel electrophoresis. 125I-labeled IL-8 exclusively bound to fast alpha 2m, and the binding could be inhibited by unlabeled IL-8. Analysis of the IL-8-alpha 2m interaction using SDS-PAGE gels indicated that the binding was mainly noncovalent. The affinity of the binding of alpha 2m to IL-8 was measured using an equilibrium dialysis technique, and Kd was 30 nM. Bioassays revealed that fast alpha 2m did not affect IL-8-induced neutrophil degranulation or chemotaxis. However, it protected IL-8 from proteolytic degradation. In addition, IL-8 complexed to alpha 2m was detected in lung fluids from patients with ARDS. alpha 2m may therefore modulate IL-8 function in the lung.
T cell receptor of Fas-sensitive T cells in rheumatoid synovium.
Authors: Sumida T , Hoa T T , Asahara H , Hasunuma T , Nishioka K 
Published: December 2022

Abstract
Apoptosis is found in synoviocytes and CD3+ T cells in the synovium of patients with rheumatoid arthritis (RA). To analyze the pathogenesis of apoptosis in rheumatoid synovium, we examined the expression of Fas Ag, Fas ligand (Fas-L), and TCR on T cells susceptible to anti-Fas mAbs. Fas Ag is expressed on 40 to 60% of CD3+ T cells in the synovium as measured by immunohistochemical and flow cytometry methods. It was observed by the reverse transcription-PCR method that Fas-L is overexpressed on T cells infiltrating the rheumatoid synovium. These results suggest that apoptosis in RA synovium is mediated by the Fas/Fas-L pathway. PCR-single-strand conformation polymorphism clearly demonstrated that more than 50% of T cells that accumulate in synovium are removed by incubation with anti-Fas mAbs for 24 h in vitro, indicating that these cells are Fas sensitive. Junctional sequence analysis revealed several conserved amino acids motifs (ERxxxSMNTE, IAAEGLLG, QxEGxD, VPD, TLAGxYNEQ, EPSE, LTNxGEL, QGK, NIP, GLL, and KWT) in the CDR3 region of accumulated Fas-sensitive T cell clones, whereas these motifs were not detected in Fas-resistant clones. In conclusion, our findings support the notion that Fas-sensitive T cells in rheumatoid synovium are generated by Ag stimulation and recognize relatively limited T cell epitopes on autoantigens, suggesting that susceptibility to anti-Fas mAbs might be a selection marker for activated autoreactive T cells in RA.
Is CTLA-4 a master switch for peripheral T cell tolerance?
Authors: Bluestone J A 
Published: December 2022

Abstract
The CD28/CTLA-4 and B7 families of cell surface molecules regulate a complex pathway of T cell signals that profoundly affect peripheral T cell responses. On the one hand, CD28/B7-mediated T cell costimulation is essential for the development and maintenance of T cell responses. In contrast, the prevailing data suggest that the engagement of CTLA-4 with the same B7 ligands down-regulates the initiation and progression of immune responses. This commentary examines the role of CTLA-4-mediated signaling in the regulation of the immune response, leading to the hypothesis that the CTLA-4/B7 interaction plays an essential role in the establishment of peripheral self-tolerance as well as the regulation of normal T cell immunity.
Down-modulation of c-myc expression induces apoptosis of B lymphocyte models of tolerance via clonal deletion.
Authors: Sonenshein G E 
Published: December 2022

Abstract
Whereas overexpression of the c-myc gene was found to promote apoptosis in fibroblasts, myeloid, and T cells, physiologic cell death of immature B cell lymphomas correlated with a drop in c-myc expression. Here, the author reviews recent evidence demonstrating that inhibition of c-myc expression activates apoptosis of B cell models of clonal deletion and that rescue from apoptosis by CD40 ligand leads to maintenance of c-Myc levels. A model of differential functional expression of the c-myc gene is discussed.
Inhibition of CPP32-like proteases prevents granzyme B- and Fas-, but not granzyme A-based cytotoxicity exerted by CTL clones.
Authors: Anel A , Gamen S , Alava M A , Schmitt-Verhulst A M , Piñeiro A , Naval J 
Published: December 2022

Abstract
The perforin-facilitated entry of granzymes in target cells is a major mechanism used by CTL to induce cell death. It has been reported that granzyme B can cleave and activate the apoptotic cysteine protease p32 (CPP32)/Yama and its homologues in vitro. However, the mechanism for granzyme-based cytolysis exerted by intact CTL remains unclear. In the present work, we have used anti-CD3 mAb-redirected lysis of Fas-negative L1210 cells by CTL clones as a model to study perforin/granzyme-based cytotoxicity separately from the contribution of the Fas/Fas ligand system. N-acetyl-Asp-Glu-Val-Asp aldehyde (Ac-DEVD-CHO), a specific inhibitor of CPP32-like proteases, completely prevented the former type of lysis in 3-h assays, but not in long-term (16-h) assays. A combination of Ac-DEVD-CHO and the granzyme A inhibitor IGA (7-(phenyl-ureido)-4-chloro-3-(2-isothioureidoethoxy)-isocoumarin) inhibited long-term cytolysis. 3,4-Dichloroisocoumarin, a serine-protease inhibitor that efficiently inhibits granzyme B and poorly inhibits granzyme A, had similar effects as Ac-DEVD-CHO on anti-CD3 mAb-redirected lysis of L1210 cells. On the other hand, Fas-based cytolysis exerted by the same CTL clones on Fas-transfected L1210 cells (L1210Fas) was inhibited completely by Ac-DEVD-CHO, irrespective of the incubation time. These results suggest that granzyme B- and Fas-based cytotoxicity exerted by CTL clones converge at the level of CPP32-like protease activation, while granzyme A acts via a different, still undefined, pathway. We also demonstrate that perforin/granzyme-based cytolysis occurs without increase in the cellular ceramide content, ruling out the contribution of the sphingomyelinase pathway to this mechanism of cell death.