bluuebunny/crossref_metadata_2025_split huggingface dataset:
IL-15 augments CD8+ T cell-mediated immunity against Toxoplasma gondii infection in mice.
Authors: Khan I A , Kasper L H 
Published: December 2022

Abstract
Cytokines of the Th1 profile are important mediators of protective host immunity against Toxoplasma gondii infection in mice. In this study we describe the effect of the recently identified cytokine, IL-15, on prevention of murine infection with T. gondii. Administration of exogenous rIL-15 with soluble Toxoplasma lysate Ag (TLA) provides complete protection against a lethal parasite challenge, whereas treatment with either rIL-15 or TLA alone is not protective. Following immunization with TLA/rIL-15, there is a significant proliferation of splenocytes expressing the CD8+ phenotype in response to TLA. A significant rise in the level of serum IFN gamma was observed in vaccinated mice. Adoptive transfer of CD8+ T cells, but not CD4+ T cells, from TLA/rIL-15-vaccinated mice protects naive mice from a lethal parasite challenge. These CD8+ T cells exhibit enhanced CTL activity against target macrophages infected with T. gondii. Mice that have been immunized are protected against lethal parasite challenge for at least 1 mo postvaccination. These observations demonstrate that TLA when administered with exogenous rIL-15 generates toxoplasmacidal Ag-specific CD8+ T cells. These T cells proliferate upon exposure to parasite Ag, exhibit long term memory CTL against infected target cells, and may be involved in host immune memory to this parasite.
Macrophages ingest and are activated by bacterial DNA.
Authors: Stacey K J , Sweet M J , Hume D A 
Published: December 2022

Abstract
Recent evidence suggests that bacterial DNA activates immune responses. Here we showed that TNF-alpha mRNA was induced in bone marrow-derived macrophages and the macrophage cell line RAW 264 by plasmid DNA, but not by DNaseI-digested plasmid, plasmid methylated on CpG dinucleotides, or by vertebrate genomic DNA, which is naturally largely methylated on these sequences. Synthetic polynucleotides poly d(I-C) and poly I x poly C also induced TNF-alpha. IL-1 beta and plasminogen activator inhibitor-2 mRNAs were induced by plasmid DNA, and IFN-gamma-pretreated macrophages responded to DNA with induction of inducible nitric oxide synthase. The HIV-1 long terminal repeat was activated by exogenous DNA in a manner similar to TNF-alpha, and was also activated by a CpG-containing oligonucleotide. Transcription factor nuclear factor-kappa B (NF-kappa B) is involved in regulation of the HIV-1 long terminal repeat and many inflammatory response genes. NF-kappa B binding activity was increased by plasmid DNA. An important question is whether these effects involve DNA binding to a cell surface receptor that signals to the interior, or whether internalization is necessary. Here we found that plasmid was taken up by RAW 264 cells and remained sufficiently intact to code for luciferase protein. Results suggest that DNA is taken up by macrophages and characteristic bacterial DNA sequences, which include an unmethylated CpG sequence, activate a signaling cascade leading to activation of NF-kappa B and inflammatory gene induction. Relevance to DNA vaccination, gene therapy, antisense, and transfection studies is discussed.
Activation of human monocytes and the acute monocytic leukemia cell line (THP-1) by lipoxins involves unique signaling pathways for lipoxin A4 versus lipoxin B4: evidence for differential Ca2+ mobilization.
Authors: Romano M , Maddox J F , Serhan C N 
Published: December 2022

Abstract
Lipoxins are bioactive eicosanoids that are generated during multicellular events such as inflammation, thrombosis, and atherosclerosis. They have selective actions on peripheral blood cells, in that previous results indicate that lipoxin A4 (LXA4) and lipoxin B4 (LXB4) inhibit neutrophil migration while they are both potent stimuli of peripheral blood monocyte (PBM) chemotaxis and adherence. Here, we report the impact of lipoxins on levels of free cytosolic calcium ([Ca2+]i) in PBM and THP-1 cells (acute monocytic leukemia cells) as well as on the functional responses of these cells. LXA4, but not LXB4, induced a concentration-dependent increase in [Ca2+]i in monocytes that was half-maximal at approximately 200 nM. Prior exposure of the cells to EGTA reduced the LXA4-induced increase in [Ca2+]i by approximately 50 to 60%, indicating the contribution of both intracellular mobilization and external influx in LXA4 Ca2+ regulation. A leukotriene B4 receptor antagonist, ONO 4057, did not significantly alter LXA4-induced [Ca2+]i, while it inhibited the action of leukotriene B4. LXA4 also induced a rise in [Ca2+]i in the monocytic leukemia cell line (time to reach maximum = 15.1 +/- 0.87 s), and both LXA4 and LXB4 stimulated a concentration-dependent THP-1 cell adherence to laminin with concentrations as low as 10(-10)M. In contrast to the findings with LXA4, exposure of THP-1 or PBM to LXB4 was not accompanied by mobilization of intracellular Ca2+. Although both LXA4 and LXB4 stimulate adherence of PBM, they did not evoke superoxide anion generation by these cells, nor did they affect the rate of acidification of extracellular medium by monocytes, as monitored using a microphysiometer. Together, these results indicate that an increase in [Ca2+]i is a component of the signal transduction events following monocyte interaction with LXA4, but not LXB4, and that both LXA4 and LXB4 are potent and selective agonists for THP-1 cells and PBM. Moreover, they suggest that LX display a unique profile of actions with mononuclear cells compared with other known agonists of monocytes, and that LX can direct monocyte-mediated events.
Genetic analysis of susceptibility to experimental autoimmune encephalomyelitis in a cross between SJL/J and B10.S mice.
Authors: Encinas J A , Lees M B , Sobel R A , Symonowicz C , Greer J M , Shovlin C L , Weiner H L , Seidman C E , Seidman J G , Kuchroo V K 
Published: December 2022

Abstract
Experimental autoimmune encephalomyelitis (EAE), a model for human multiple sclerosis, is a T cell-mediated autoimmune disease that can be induced in experimental animals by immunization with myelin Ags. Inbred strains of mice show varying degrees of susceptibility to EAE, indicating that susceptibility is an inherited trait. To define the genetic factors that control susceptibility to EAE, we performed linkage analysis on the first backcross (BC1) between highly susceptible SJL/J mice and resistant B10.S mice, both of which are of the H-2s haplotype. Mice were immunized for disease with encephalitogenic myelin proteolipid protein peptide 139 to 151, and analysis was performed on 68 backcross mice showing the severe disease phenotype (disease score &gt; or = 3)and 68 backcross mice of the resistant phenotype (no clinical or histologic signs of disease) using microsatellite markers covering &gt;98% of the genome. We found the strongest linkage (p = 0.001) with clinical disease at two loci: one at the telomeric end of chromosome 2, and another near the center of chromosome 3. In addition, several other regions showing some evidence of linkage (p &lt; or = 0.05) with clinical disease were found.
Multifactor cis-dominant negative regulation of IL-2 gene expression in anergized T cells.
Authors: Kitagawa-Sakakida S , Schwartz R H 
Published: December 2022

Abstract
The molecular mechanism underlying IL-2 transcriptional blockade in anergic T cell clones is not fully understood. To examine whether an active negative regulatory process occurs, we created a reporter construct containing as an enhancer four copies of the NF-AT site and one copy of the octamer site (4X NF-AT-Oct). This construct was only slightly reduced (1.3-fold) in its expression when stimulated under anergic conditions, while a whole mouse IL-2 enhancer construct showed a reduction of 4.3-fold. Addition of the -176 to -96 sequence to the 4X NF-AT-Oct construct did not impart the ability to be affected by anergy, but addition of the -236 to -96 sequence did, demonstrating that anergy is an active inhibitory process and that more than the presence of the -150 AP-1 binding site (-152 to -147) is required to mediate the effect. Mutational studies of the -236 to -96 sequence indicated that the presence of both the -130 AP-1-like site (-187 to -181) and the -150 proximal AP-1 site were necessary to observe anergy. Because the -180 site is not required for trans-activation, it was possible to confirm by mutation in the normal mouse IL-2 enhancer that this site is absolutely essential for anergy induction. The simplest model to explain these results is that anergy is mediated by a complex of multiple transcription factors that exert a cis-acting dominant negative regulatory effect on the trans-activation of the IL-2 gene.
Alloreactive monoclonal antibodies select Kd molecules with different peptide profiles.
Authors: Noun G , Reboul M , Abastado J P , Jaulin C , Kourilsky P , Pla M 
Published: December 2022

Abstract
As a part of our continuing effort to study the antigenic structure of class I molecules, we have undertaken two types of studies. First, we have studied the capacity of five different Kd-reactive mAbs to recognize a panel of 25 site-directed mutants of the H-2Kd molecule. Both the gain and the decrease in Ab binding resulted from a single amino acid substitution at different positions. All mutations that increase the binding of the tested mAbs are located on the alpha-helices, indicating that the replacement of an Ig-contacting surface residue with a charged or polar side chain by a short one generally favors Ab binding. Mutation of two alpha-helix-situated residues, 58 and 166, completely abolished the binding of one mAb (Tu191.7.1), indicating that these two residues contribute to the antigenic determinant defined by this mAb. The overwhelming majority of mutations that diminished Ab binding concerns residues buried within the Ag binding groove, suggesting the possibility of peptide contribution to serologic epitopes defined by alloreactive Abs. We have addressed this issue by comparison of the repertoire of peptides eluted from Kd molecules precipitated by different Kd-reactive mAbs. The results reveal that the two-dimensional profile obtained with one (F35.119.18) of the alloreactive mAbs is clearly different. The use of 21 single amino acid variants of a Kd-restricted 10-mer peptide allowed us to identify the residue of the bound peptide contributing to the epitope recognized by this mAb. Thus, we have shown that at least in some instances, changes induced in the MHC molecules by the binding of distinct peptides can be recognized as alterations in serologic determinants expressed on the class I molecules.
IL-4 is protective against development of toxoplasmic encephalitis.
Authors: Suzuki Y , Yang Q , Yang S , Nguyen N , Lim S , Liesenfeld O , Kojima T , Remington J S 
Published: December 2022

Abstract
IFN-gamma is critical for prevention of development of toxoplasmic encephalitis (TE). Since IL-4 down-regulates production of IFN-gamma, we examined its role in the pathogenesis of TE in IL-4-targeted mutant (IL-4-/-) mice. IL-4-/- mice all died from 6 to 20 wk after peroral infection with cysts of the ME49 strain of Toxoplasma gondii; control mice survived. At 4 and 8 wk after infection, significantly greater numbers of T. gondii cysts and foci of acute inflammation, and greater amounts of tachyzoite-specific mRNA (by reverse-transcriptase PCR) were in brains of IL-4-/- mice than controls. Toxoplasma IgG2b and IgG3 Ab levels were slightly but significantly higher in sera of IL-4-/- than control mice, whereas IgM and IgG2a levels did not differ between these mice. Toxoplasma IgG1 and IgE Abs were not detected in sera of either strain. Amounts of IFN-gamma, TNF-alpha, IL-6, and IL-10 mRNA detected by reverse-transcriptase PCR did not differ between brains of infected IL-4-/- and controls, although brains of the former mice had greater numbers of inflammatory mononuclear cell infiltrates. IL-4 mRNA was detected only in infected control mice. Spleen cells of control mice at 8 wk after infection produced significantly greater amounts of IFN-gamma following stimulation in vitro with soluble T. gondii Ags than did those from IL-4-/- mice. These results indicate that IL-4 is protective against development of TE by preventing formation of T. gondii cysts and proliferation of tachyzoites in the brain. The impaired ability of IL-4-/- mice in the late stage of T. gondii infection to produce IFN-gamma most likely contributes to their susceptibility for development of severe TE.
Quantum proteolysis resulting from release of single granules by human neutrophils: a novel, nonoxidative mechanism of extracellular proteolytic activity.
Authors: Liou T G , Campbell E J 
Published: December 2022

Abstract
Proteinase inhibitors confine the activity of proteolytic enzymes of inflammatory cells, but fail to protect substrates in the immediate pericellular zone. We report quantitative imaging that demonstrates discrete, evanescent, quantized proteolytic events attributable to the release of single azurophil granules from neutrophils. The images provide information about the dynamics of this nonequilibrium system, which is characterized by overwhelmingly high local concentrations of enzymes that rapidly dissipate. With physiologic concentrations of extracellular human leukocyte elastase inhibitors (32.8 microM), the radii of the unit proteolytic events are 1.32 microm (approximately 8 times the radius of the azurophil granule) and are inversely and nonlinearly related to the concentration of proteinase inhibitor that is present in the bathing medium. We have obtained identical results with alpha1-antitrypsin, alpha2m, recombinant secretory leukocyte proteinase inhibitor, and ICI 200,355, and we have found that phagocyte-derived oxidants are not required for the genesis of this catalytic activity. Our results reveal that the enzyme:inhibitor ratio is the primary delimiter of quantized proteolysis in the local microenvironment.
Monocyte IL-8 release is induced by two independent Fc gamma R- mediated pathways.
Authors: Marsh C B , Anderson C L , Lowe M P , Wewers M D 
Published: December 2022

Abstract
Cross-linking of PBMC and monocyte Fc gamma R on immobilized IgG stimulates IL-8 release. We used immobilized anti-Fc gamma R Abs to determine which of the three surface Fc gamma R regulated this IL-8 secretion. Fc gamma RIII cross-linking stimulated PBMC to release 5 times more IL-8 than did either Fc gamma RI or Fc gamma RII clustering (p = 0.001) and stimulated 77% more IL-8 release from PBMC than that from purified monocytes (p = 0.001). In contrast, only Fc gamma RI cross-linking significantly induced monocytes to release IL-8 (p = 0.05). Since purified lymphocytes release little IL-8 in response to immobilized IgG or anti-Fc gamma RIII Abs, we hypothesized that lymphocyte Fc gamma R cross-linking augmented monocyte IL-8 release. Supernatants from IgG- or Fc gamma RIII -stimulated lymphocytes induced monocytes to release more IL-8 than lymphocytes incubated on plastic alone (p = 0.002 and p = 0.003, respectively). THP-1 cells, which do not produce IL-8 in response to Fc gamma i]R cross-linking, also released IL-8 in response to supernatants from IgG- or Fc gamma RIII-stimulated lymphocytes, suggesting that the supernatant activity was not soluble immune complexes. The IL-8-stimulating activity was heat labile, suggesting that the activity is a protein. However, we could not reproduce or block this activity using recombinant cytokines or neutralizing anti-cytokine Abs. Thus, monocyte IL-8 is stimulated directly through Fc gamma RI cross-linking and indirectly through an Fc gamma RIII-stimulated soluble lymphocyte factor.
Single cell analysis of IL-4 and IFN-gamma production by T cells from HIV-infected individuals: decreased IFN-gamma in the presence of preserved IL-4 production.
Authors: Meyaard L , Hovenkamp E , Keet I P , Hooibrink B , de Jong I H , Otto S A , Miedema F 
Published: December 2022

Abstract
The specific in vitro disturbance of capacities ascribed to Th1 cells in HIV-infected individuals suggests a switch from Th1 to Th2 lymphokine secretion. Indeed, when T cell clones are generated from HIV-infected individuals compared with controls, an increased percentage of Th0 clones is present upon HIV infection. We studied cytokine production in the supernatant of in vitro activated PBMC from a large group of HIV-infected patients at various stages of infection. IL-2, IFN-gamma, IL-4, IL-5, and IL-10 production all were decreased significantly, which does not support a switch to Th2 lymphokine secretion and is possibly due to the generalized impaired response of T cells from HIV-infected individuals to activation signals in vitro. Therefore, we investigated the capacity of single cells to produce a certain cytokine. Intracellular staining of IL-4- and IFN-gamma-producing cells revealed that T cells from HIV-infected individuals contained decreased numbers of IFN-gamma-producing cells, in the presence of normal percentages of cells with the capacity to produce IL-4. This resulted in significantly decreased IFN-gamma/IL-4 ratios in both CD4+ and CD8+ T cells. Thus, in agreement with previous findings in T cell clones, we conclude, from cytokine production upon stimulation of T cells in vitro, that there is a change in the cytokine balance to the Th2 side in HIV infection due to decreased Th1 and preserved Th2 cytokine production.
Apoptosis induced by HIV infection in H9 T cells is blocked by ICE-family protease inhibition but not by a Fas(CD95) antagonist.
Authors: Glynn J M , McElligott D L , Mosier D E 
Published: December 2022

Abstract
Infection of human CD4-positive T lymphocytes by human immunodeficiency virus type 1 (HIV-1) is thought to lead to death of infected cells by apoptosis, although one recent report questions this conclusion. Here we demonstrate that HIV-1-induced apoptosis of the H9 human T cell line is blocked by peptide inhibitors of IL-1 beta converting enzyme (ICE)-family proteases, but not by the antagonistic M3 anti-Fas Ab. Apoptosis occurred in all phases of the cell cycle, not selectively in G2 as a consequence of vpr-mediated cell cycle arrest. We conclude that apoptosis accounts for all cell death related to HIV-1 infection of the human CD4-positive cell line H9, requires an ICE-like protease but is not Fas mediated, and occurs in all phases of the cell cycle.
Molecular cloning of TER1, a chemokine receptor-like gene expressed by lymphoid tissues.
Authors: Napolitano M , Zingoni A , Bernardini G , Spinetti G , Nista A , Storlazzi C T , Rocchi M , Santoni A 
Published: December 2022

Abstract
Several chemokine receptors have been cloned and shown to belong to a superfamily of seven transmembrane, G protein-coupled receptors. We report here the molecular cloning of TER1, a novel human chemokine receptor-like gene. The amino acid sequence deduced from the TER1 cDNA shows 43, 40, 40, and 39% identity to CCR4, CCR5, CCR1, and CCR2B beta chemokine receptors, respectively. By the use of fluorescent in situ hybridization, we have mapped the TER1 gene to chromosome 3p21, clustered with other chemokine receptor genes. By Northern blot analysis, TER1 mRNA is found to be expressed in the thymus, spleen, and at barely detectable levels in peripheral blood lymphocytes. Moreover, TER1 message in abundant in the NK cell line NK3.3 and in the T cell line MOLT-4. The restricted TER1 expression in cells and tissues of the lymphoid lineage suggests that this receptor may play a role in regulating immune functions.
CD40L is important for induction of, but not response to, costimulatory activity. ICAM-1 as the second costimulatory molecule rapidly up-regulated by CD40L.
Authors: Shinde S , Wu Y , Guo Y , Niu Q , Xu J , Grewal I S , Flavell R , Liu Y 
Published: December 2022

Abstract
The CD40 ligand (CD40L):CD40 interaction plays an important role in the activation of both T and B cells. However, the mechanisms by which this interaction is involved in activation of T cells is still unclear. Here we show that CD40L is not essential for T cell response to TCR engagement if the APC have costimulatory activity, although it is essential for T cell-mediated induction of such costimulatory activity. To determine the molecular basis of this activity, we have produced three mAbs that appear to recognize the costimulatory molecules rapidly induced by CD40L. Two of them recognize CD44H, which we showed to have CD28-independent costimulatory activity for T cells. The molecule recognized by the remaining mAb is hereby identified as ICAM-1. Furthermore, ICAM-1-mediated costimulation is likely to serve for a function similar to that mediated by the B7:CD28 interaction, as targeted mutation of CD28 renders T cell responses to Con A more dependent on ICAM-1.
A role for phosphatidylinositol 3-kinase in generating T cell help for B cell growth and differentiation.
Authors: Aagaard-Tillery K M , Jelinek D F 
Published: December 2022

Abstract
Evidence supporting the importance of the 3-phosphoinositide signaling pathway in lymphocyte activation is rapidly accumulating. In our study, we assessed the effects of two PI 3-kinase inhibitors, wortmannin and LY294002, on T cells as a means to analyze the role of the PI 3-kinase-signaling pathway in the generation of T cell help for B cell growth and differentiation. For these studies, B cells were cocultured with CD3-activated mitomycin C-treated T cells to induce B cell responsiveness. Of interest, wortmannin or LY294002 pretreatment of the T cell population significantly inhibited T cell-dependent induction of B cell proliferation and differentiation. The failure of wortmannin-treated CD3-activated mitomycin C-treated T cells to provide help in driving the differentiation of B cells to Ig-secreting cells could not be corrected by the addition of exogenous IL-2. Further studies designed to elucidate the mechanism by which wortmannin-treated T cells failed to provide B cell help indicated that wortmannin and LY294002 significantly inhibited the induction of CD40 ligand and, to a lesser extent, intercellular adhesion molecule-1 expression. These results suggest that the PI 3-kinase-signaling pathway, or other wortmannin- and LY294002-sensitive pathways, may be important for the induction of expression of crucial interaction molecules, such as CD40 ligand, on T cells and thus indicates that D-3 phosphoinositides play a pivotal role in regulating T cell-dependent B cell activation.
B cell responses to a peptide epitope. I. The cellular basis for restricted recognition.
Authors: Agarwal A , Sarkar S , Nazabal C , Balasundaram G , Rao K V 
Published: December 2022

Abstract
Primary humoral responses in BALB/c mice to a variety of peptide constructs containing a common 15-amino acid residue antigenic determinant (PS1) in conjunction with one or more Th cell epitopes were examined. In all cases, the mature IgG response was found to focus primarily on a tetrapeptide sequence, Asp-Pro-Ala-Phe. The dominance of this segment was independent of the position of the PS1 determinant in the peptide sequence and was also observed in constructs with a random secondary structure. In contrast to the mature IgG response, the early primary IgM response was constituted by multiple specificities that collectively spanned a major proportion of the PS1 sequence. However, subsequent progression of this response entailed a strict selection for only those Abs directed against the Asp-Pro-Ala-Phe segment and apparently occurred at or around the time of the IgM to IgG class switch. Studies of murine responses to peptide analogs containing single amino acid substitutions within the Asp-Pro-Ala-Phe sequence revealed that emergence of this segment as the dominant epitope was a consequence of active suppression of B cells directed against alternate determinants. Positive selection of this subset of Abs correlated with overall higher avidity for epitope binding and was the outcome of a competitive process enforced by the limiting amounts of Th cell help available in the early stages of the primary response.