bluuebunny/crossref_metadata_2025_split huggingface dataset:
Slow release of soluble TNF receptors by monocytes in vitro.
Authors: Leeuwenberg J F , Jeunhomme T M , Buurman W A 
Published: December 2022

Abstract
In this study, we investigated the release of soluble(s) TNF-R by PBMC in vitro. T cell activation by mAb anti-CD3, as well as activation with phorbol esters (PMA), enhanced the release of both sTNF-R55 and sTNF-R75 by PBMC. In contrast to shedding of TNF-R by neutrophils upon activation, release of sTNF-R by PBMC proved to be a relatively slow process, reaching a plateau after 2 days of culture. Monocytes appeared to be the main source of the released sTNF-R, whereas activation of purified T cells induced only a minor release of sTNF-R as compared with the whole cell population. To unravel the mechanism, a number of cytokines were added during a 2-day culture of cells. IL-10 enhanced sTNF-R levels with similar kinetics as mAb anti-CD3 and PMA, whereas the other cytokines tested did not affect the release of sTNF-R by PBMC, pure T lymphocytes, or purified monocytes, either activated or not. Conversely, inhibitors of cytokines were added during the activation period to study the effect of endogenously produced cytokines on sTNF-R release. mAb anti-IL-10 and IL-1ra partly sTNF-R release, whereas other inhibitors did not affect the release. The results obtained in vitro may extend our insight in the mechanism via which sTNF-R are enhanced in vivo during inflammatory reactions.
Pertussis toxin interferes with superantigen-induced deletion of peripheral T cells without affecting T cell activation in vivo. Inhibition of deletion and associated programmed cell death depends on ADP-ribosyltransferase activity.
Authors: Gonzalo J A , González-García A , Baixeras E , Zamzami N , Tarazona R , Rappuoli R , Martínez C , Kroemer G , Tarazona R , Terezone R 
Published: December 2022

Abstract
Intravenous injection of a bacterial superantigen such as Staphylococcus aureus enterotoxin B (SEB) causes transient activation and expansion of SEB-reactive V beta 8+ T cells, as well as specific down-regulation of the immune response, through partial deletion of superantigen-reactive T cells. Here we demonstrate that co-administration of pertussis toxin (PTX) and SEB reduces the SEB-induced deletion of V beta 8+ T cells, although it does not affect T cell activation and proliferation. PTX abrogates the SEB-driven deletion of V beta 8+CD4+ (not V beta 8+CD8+) splenocytes that is observed early (12-24 h) after SEB injection. Moreover, it antagonizes the late (&gt; or = 4 days) deletion of V beta 8+CD4+ and V beta 8+CD8+ peripheral T cells that follows transient expansion of such cells. This phenomenon is associated with significant reductions in apoptosis and endonucleolysis and is not caused by a compensatory increase in proliferation of SEB-reactive T cells, as we determined by using a combined fluorometric analysis of cell cycle and DNA alterations, which are associated with programmed cell death. These effects are also observed in thymectomized animals, thus excluding the possibility that PTX might act by enhancing the maturation and export of thymic T cells to the periphery. Moreover, the SEB-induced reduction of V beta 8+ splenocytes is antagonized by PTX in vitro. The capacity of PTX to reduce clonal deletion depends critically on its ADP-ribosyltransferase activity, inasmuch as a non-enzymatic PTX mutant fails to act in this biologic system. We conclude that PTX selectively antagonizes or impedes the delivery of negative signals to T cells, which are stimulated by superantigens, without interfering with the transmission of stimulatory signals.
Inhibition of in vivo tumor growth by the beta chemokine, TCA3.
Authors: Laning J , Kawasaki H , Tanaka E , Luo Y , Dorf M E 
Published: December 2022

Abstract
TCA3 is a proinflammatory murine glycoprotein that shares structural features with cytokines of the beta chemokine family and is a chemoattractant for neutrophils and monocytes. To assess the in vivo functions of TCA3, the cDNA was expressed in two mouse myeloma cell lines. Although the transfected and control cells had similar growth rates in vitro, TCA3-expressing tumors demonstrated impaired growth in both normal and immunodeficient mice. Histologic evaluation of the injection sites demonstrated that TCA3 expression resulted in an early neutrophil and monocyte infiltrate accompanied by tumor necrosis. There was complete regression of the TCA3-transfected tumor in some immunocompetent syngeneic mice. The TCA3-transfected cells induced specific and long-lasting immunity in mice that showed complete tumor regression; these animals were resistant to challenge with nontransfected tumor cells. In contrast, priming with irradiated tumor cells provided little protection against challenge with nontransfected tumor, which indicates that TCA3 specifically augments tumor immunogenicity. Mixing TCA3-transfected cells with normal tumor cells causes retarded growth of the normal tumor cells provided the latter are injected into the same site. Furthermore, direct in situ injection of soluble rTCA3 early during the course of tumor implantation also inhibits tumor growth. The data suggest that TCA3 may perform two roles in tumor protection: it induces lymphocyte-independent antitumor activity and stimulates tumor-specific immunity. We speculate that TCA3 has natural adjuvant activities that result in augmented immune responses.
Modulation of the in vivo immune response by selective depletion of neutrophils using a monoclonal antibody, RP-3. III. Enhancement by RP-3 treatment of the anti-sheep red blood cell plaque-forming cell response in rats.
Authors: Tamura M , Sekiya S , Terashita M , Sendo F 
Published: December 2022

Abstract
Because recent work has shown that neutrophils produce various cytokines and are activated by these agents, this study was undertaken to examine neutrophil participation in immune networks. In our previous work, we demonstrated that delayed type hypersensitivity to SRBC and accompanying mononuclear leukocyte recruitment are inhibited in vivo by selective depletion of neutrophils using a mAb designated RP-3. To elucidate the function of these cells in Ab production, we assessed the splenic plaque-forming cell response to SRBC in a rat model through selective depletion of circulating neutrophils by RP-3. This depletion which occurred at the time of immunization resulted in an increase in the number of anti-SRBC Ab producing cells, as determined by the direct and indirect plaque-forming cell response. This phenomenon was observed only when the Ag was administered i.p. and not with i.v. immunization. These results suggest that neutrophils suppress Ab production in certain situations.
Xanthine dehydrogenase and xanthine oxidase activity and gene expression in renal epithelial cells. Cytokine and steroid regulation.
Authors: Pfeffer K D , Huecksteadt T P , Hoidal J R 
Published: December 2022

Abstract
Reactive oxygen species have been implicated in the tissue injury and loss of epithelial barrier function associated with a number of clinical disorders in which disregulated inflammation seems to be a dominant event, such as endotoxemia and viral syndromes. In these disorders, xanthine oxidase (XO) contained within the epithelial cell has been proposed as a major source of injurious reactive oxygen species. This study was undertaken in an effort to understand the regulation of xanthine dehydrogenase (XDH)/XO expression at both the activity and gene expression levels in the epithelial cell under conditions associated with the inflammatory response. The results indicate that TNF, IFN-gamma, IL-6, IL-1, and dexamethasone induce XDH/XO activity in bovine renal epithelial cells (MDBK). This pattern of XDH/XO regulation by cytokines and steroids is analogous to the profile of response seen by acute phase reactants. Metabolic labeling and immunoprecipitation revealed the increase in XDH/XO activity requires new protein synthesis. By Northern analysis, all cytokines and dexamethasone increased the level of the 5-kb XDH/XO mRNA. This increase was not detectable in the presence of actinomycin D but was further induced in the presence of cycloheximide, consistent with the major site of XDH/XO up-regulation occurring at the transcriptional level. XDH/XO mRNA was very stable, with no indication that the rates of transcript degradation contributed to differences in mRNA accumulation or ultimate activity levels. In addition to providing information on the regulation of XDH/XO, the data presented furthers the understanding of the epithelial cell's potential to actively respond to immunomodulators associated with injury/inflammation.
Characteristics of an in vitro system of thymocyte positive selection.
Authors: Anderson G , Owen J J , Moore N C , Jenkinson E J 
Published: December 2022

Abstract
We investigated the phenotypic changes accompanying maturation of CD4+CD8+ thymocytes in the presence of thymic stomal cells in vitro. Many of the features that are characteristic of positive selection in vivo, such as an ordered down-regulation of CD4 or CD8 together with up-regulation of the TCR-alpha beta complex, also occurred in vitro. Transient expression of CD69 was also observed, together with activation of IL-2 and IL-4 cytokine genes, providing further evidence that positive selection in vitro involves a pattern of gene regulation comparable to that seen in vivo.
A cross-reactive idiotope on T cells from PL/J mice and Lewis rats that recognizes different myelin basic protein encephalitogenic epitopes but is restricted by TCR V beta 8.2.
Authors: Zhou S R , Whitaker J N , Han Q , Maier C , Blalock J E 
Published: December 2022

Abstract
Encephalitogenic T cells of both PL/J mice and Lewis rats are restricted by TCR V beta 8.2, although they recognize different epitopes in the myelin basic protein (MBP) molecule. We sought the presence of a cross-reactive idiotope (Id) in encephalitogenic T cells of Lewis rats by examining the effects of mAb F30 anti-Id, which recognized a TCR Id in PL/J T cells, on the encephalitogenic LR88L1 cell line derived from Lewis rats and specific for guinea pig MBP peptide 68-88. The LR88L1 cells were I-A restricted and TCR V beta 8.2+, and their proliferation and secretion of IL-2 and TNF-alpha induced by guinea pig MBP peptide 68-88 was inhibited by mAb F30 anti-Id. As shown by FACS analysis and by immunoprecipitation of TCR from radiolabeled LR88L1 cell lysates, the F30 anti-Id bound to the TCRs of V beta 8.2+ LR88L1 cells. In addition, TCR sequences in the F30+ population of LR88L1 cells were the same as those of encephalitogenic Lewis rat T cells published previously. The F30+ LR88L1 cells showed reduced encephalitogenicity compared with F30- or unsorted LR88L1 cells. The mechanism for this reduction by anti-Id probably resulted from the induction of anergy, in that IL-2 reversed the anti-Id effect. The control LR99L1 T cell line, also encephalitogenic, but specific for MBP peptide 87-99 and I-E, and not TCR V beta 8.2 restricted, failed to react with, or have its cytokine secretion inhibited by, mAb F30 anti-Id. These results demonstrate an interspecies cross-reactive Id expressed in common by encephalitogenic T cells that share a similar TCR, although they differ in MBP epitope specificity. These findings suggest that a common Id restricted by TCR, but less restricted by the encephalitogenic epitope, and recognized by the Id-bearing autoreactive T cells may represent an immunotherapeutic approach for treating autoimmune demyelinating diseases.
Rapamycin inhibits production of cytotoxic but not noncytotoxic antibodies and preferentially activates T helper 2 cells that mediate long-term survival of heart allografts in rats.
Authors: Ferraresso M , Tian L , Ghobrial R , Stepkowski S M , Kahan B D 
Published: December 2022

Abstract
Rapamycin (RAPA) induces unresponsiveness toward heart allografts by at least two mechanisms: selective production of noncytotoxic IgG2c-blocking Ab and preferential activation of Th2 cells. RAPA (0.8 mg/kg/day) delivered via a 14-day osmotic pump to Wistar Furth (WF; RT-1u) recipients prolongs Buffalo (BUF; RT-1b) heart allograft survival from a mean survival time (MST) of 6.5 +/- 0.5 days to 75.0 +/- 18.9 days (n = 18; p &lt; 0.001), with 6 of 18 grafts beating for more than 100 days. Recipient sera or their IgG but not IgM fraction, obtained after postgrafting day 40, passively transfer the unresponsive state to sublethally irradiated secondary recipients in a dose-dependent and immunologically-specific fashion. Sera obtained after untreated WF hosts rejected BUF hearts contained IgG moieties of all subclasses that bound to class I MHC BUF epitopes. In contrast, the unresponsive sera contained predominantly non-C'-fixing IgG2c and only marginal amounts of activated (C') fixing IgG1, IgG2a, and IgG2b Ab. The transcription of IL-2, IL-4, and IL-10 mRNAs was assessed using a PCR method. There were similar increases in the levels of IL-2, IL-4, and IL-10 mRNA in heart allografts from both untreated and RAPA-treated recipients on day 5 postgrafting. In contrast, on days 60 and 300 postgrafting heart allografts from RAPA-treated unresponsive recipients showed increased levels of IL-10 and IL-4 but not of IL-2 mRNA, suggesting preferential activation of Th2 cells. Thus, RAPA treatment selectively inhibits the synthesis of C'-binding of IgG subclasses, spares the non C-binding blocking IgG2c Ab, and preferentially activates Th2 cells.
Characterization of soluble CD44 in the circulation of mice. Levels are affected by immune activity and tumor growth.
Authors: Katoh S , McCarthy J B , Kincade P W 
Published: December 2022

Abstract
ELISA determinations revealed substantial concentrations (0.49 to 2.10 micrograms/ml) of soluble CD44 in murine serum, with some variation among normal mouse strains. At least three species of CD44 were identified by immunoprecipitation and SDS-PAGE analysis of serum. The most prominent was indistinguishable in mobility from that extracted from normal and transformed lymphocytes and was estimated in this way to be approximately 90 kDa. A similar estimate resulted from gel filtration under nondenaturing conditions, followed by ELISA. However, lymphocyte membrane-extracted and soluble CD44 had different mobilities after treatment with neuraminidase plus O-glycosidase, and the core protein of soluble CD44 might be 17 to 20 kDa smaller than that of CD44 on lymphocyte membranes. Furthermore, an Ab to cytoplasmic residues of CD44 failed to recognize soluble CD44 recovered from the circulation or in lymphoma culture supernatants. These observations would be consistent with cleavage of CD44 from cell surfaces; and protease inhibitors slowed the loss of CD44 from cultured lymphomas. Serum CD44 levels were significantly reduced in immunodeficient CD17.SCID and BALB/c.Xid mice, and elevated in tumor-bearing mice. Mild graft-vs-host (GVH) reactions also resulted in increased concentrations of CD44, as did autoimmune disease in BXSB and MRL/lpr strains of mice. Serum with high concentrations of CD44 partially blocked the binding of one ligand, hyaluronate, to CD44-bearing hybridoma cells. The degree of inhibition was positively correlated with CD44 concentration. These findings indicate that substantial quantities of CD44 can be released into the circulation by cleavage from cell surfaces and that this process is markedly influenced by immune system activity and tumor growth. The material seemed to be intact and potentially functional.
Multiple defects in innate and adaptive immunologic function in NOD/LtSz-scid mice.
Authors: Shultz L D , Schweitzer P A , Christianson S W , Gott B , Schweitzer I B , Tennent B , McKenna S , Mobraaten L , Rajan T V , Greiner D L 
Published: December 2022

Abstract
The scid mutation was backcrossed ten generations onto the NOD/Lt strain background, resulting in an immunodeficient stock (NOD/LtSz-scid/scid) with multiple defects in adaptive as well as nonadaptive immunologic function. NOD/LtSz-scid/scid mice lack functional lymphoid cells and show little or no serum Ig with age. Although NOD/(Lt-)+/+ mice develop T cell-mediated autoimmune, insulin-dependent diabetes mellitus, NOD/LtSz-scid/scid mice are both insulitis- and diabetes-free throughout life. However, because of a high incidence of thymic lymphomas, the mean lifespan of this congenic stock is only 8.5 mo under specific pathogen-free conditions. After i.v. injection of human CEM T-lymphoblastoid cells, splenic engraftment of these cells was fourfold greater in NOD/LtSz-scid/scid mice than in C.B17/Sz-scid/scid mice. Although C.B-17Sz-scid/scid mice exhibit robust NK cell activity, this activity is markedly reduced in both NOD/(Lt-)+/+ and NOD/LtSz-scid/scid mice. Presence of a functionally less mature macrophage population in NOD/LtSz-scid/scid vs C.B-17Sz-scid/scid mice is indicated by persistence in the former of the NOD/Lt strain-specific defect in LPS-stimulated IL-1 secretion by marrow-derived macrophages. Although C.B-17Sz-scid/scid and C57BL/6Sz-scid/scid mice have elevated serum hemolytic complement activity compared with their respective +/+ controls, both NOD/(LtSz-)+/+ and NOD/LtSz-scid/scid mice lack this activity. Age-dependent increases in serum Ig levels (&gt; 1 micrograms/ml) were observed in only 2 of 30 NOD/LtSz-scid/scid mice vs 21 of 29 C.B-17/Sz-scid/scid animals. The multiple defects in innate and adaptive immunity unique to the NOD/LtSz-scid/scid mouse provide an excellent in vivo environment for reconstitution with human hematopoietic cells.
Activated human NK cells can stimulate resting B cells to secrete immunoglobulin.
Authors: Gray J D , Horwitz D A 
Published: December 2022

Abstract
In addition to their cytotoxic function, NK cells can either suppress or enhance Ab production. Upon activation, NK cells generally amplify Ig secretion by activated B cells. We now report that activated NK cells prepared from human peripheral blood can induce resting B cells to produce IgM and IgG. This was demonstrated by adding IL-2 or pokeweed mitogen to purified NK cells and B cells. The addition of IL-2-activated NK cells to B cells also had this effect. The responding B cells did not require activation. Moreover, following fractionation of B cells on Percoll gradients, responsive B cells were found in the high density as well as the low density fractions. The NK cell stimulatory effect was a two-step process. The first step induced B cells to respond to soluble mediators and was mediated by unstimulated NK cells, but not CD4 nor CD8 T cells. Physical contact between NK cells and B cells was required, and mAbs to CD11a and CD54 blocked this interaction. The second step was the production of as yet unidentified cytokine(s) by activated NK cells. These direct T cell-independent stimulatory effects of NK cells on B cells may be important in autoimmune and other chronic inflammatory diseases in which the suppressive effects of NK cells may be blocked.
Up-regulation of inducible cyclooxygenase gene expression by platelet-activating factor in activated rat alveolar macrophages.
Authors: Thivierge M , Rola-Pleszczynski M 
Published: December 2022

Abstract
Platelet-activating factor (PAF) can stimulate alveolar macrophages (AM) to produce IL-6 through a PG-dependent process. In this study, the modulation by PAF of the expression of COX-2, the inducible isoform of PG synthase, was investigated. Expression of COX-2 mRNA was increased in rat AM within 2 h after treatment with either of the bacterial products LPS or muramyl dipeptide (MDP) alone. Although PAF had no effect by itself, stimulation of AM with a combination of PAF (10(-10) to 10(-8) M) and LPS or MDP resulted in a synergistic, three- to fivefold increase in levels of COX-2 mRNA. No significant change was observed in the mRNA expression of the constitutive isoform, COX-1. The antagonist WEB 2170 blocked the action of PAF, whereas lyso-PAF was inactive on the COX-2 gene expression. The effect of PAF was rapid, being evident by 30 to 60 min of stimulation and was accompanied by enhanced production of PGE2. Two relatively selective inhibitors of COX-2 abolished the PAF-dependent increase in PGE2 production. Moreover, inhibition of transcription with actinomycin D completely abrogated the effect of PAF on both COX-2 mRNA and PGE2 production. These results suggest that COX-2 expression can be regulated at the transcriptional level by PAF, in synergy with bacterial products. PAF-dependent up-regulation of COX-2 expression may constitute a novel element in the interrelationship between PAF and prostanoids in the context of allergic, inflammatory, and immune processes.
Neutralizing recombinant human antibodies to a conformational V2- and CD4-binding site-sensitive epitope of HIV-1 gp120 isolated by using an epitope-masking procedure.
Authors: Ditzel H J , Binley J M , Moore J P , Sodroski J , Sullivan N , Sawyer L S , Hendry R M , Yang W P , Barbas C F , Burton D R 
Published: December 2022

Abstract
As part of the goal of assembling a mixture of neutralizing human mAbs for possible prophylaxis and therapy of HIV-1 disease, we describe a strategy by which neutralizing human Abs to a weakly immunogenic epitope can be accessed. From a phage display library derived from an asymptomatic HIV-1 seropositive donor, a panel of recombinant Fabs against the CD4 binding site (CD4bs) of gp120 was retrieved by affinity selection using recombinant gp120 (strain LAI). Two Fabs corresponding to the dominant clones were used to mask the CD4bs epitope(s) before repeating the selection procedure. Four Fabs were then retrieved that had novel heavy chain sequences. Three recognized a novel epitope distinct from that recognized by conventional CD4bs Abs and were defined by the following criteria: 1) second V region (V2 region) dependence indicated by sensitivity to amino acid changes in the V2 loop and by competition with murine anti-V2 mAbs; 2) CD4bs dependence indicated by sensitivity to amino acid changes usually associated with CD4 binding and by inhibition of Fab binding to gp120 by soluble CD4; this dependence seemed to arise via conformational changes rather than by direct binding, as CD4bs Abs enhanced binding of two of the novel Fabs and, in a reversal of the competition format, the novel Fabs did not inhibit soluble CD4 binding to gp120; and 3) equivalent binding to glycosylated and deglycosylated gp120 and significant, although much reduced, binding to denatured gp120 in contrast with CD4bs Abs, which do not bind to deglycosylated or denatured gp120. One of the novel Fabs efficiently neutralized the MN and LAI strains of HIV-1. These results indicate the presence of a novel neutralizing conformational epitope on gp120 sensitive to the V2 loop and the CD4bs and further highlight the conformational flexibility of gp120. The strategy of masking highly immunogenic epitopes with Abs to rescue a broader range of specific Abs from combinatorial libraries should be widely applicable.
Growth hormone is a human macrophage activating factor. Priming of human monocytes for enhanced release of H2O2.
Authors: Warwick-Davies J , Lowrie D B , Cole P J 
Published: December 2022

Abstract
Although many effects of growth hormone (GH) and related factors upon the immune system have been demonstrated, few studies have examined the capacity of these factors to modulate human monocyte function in vitro. Assaying a range of mediators, only GH and prolactin (PRL), at 0.3 to 1.0 micrograms/ml, and growth hormone-releasing hormone (GRH) at very high doses, primed monocytes for enhanced hydrogen-peroxide production (H2O2) in response to PMA. GH-induced priming was not caused by endotoxin, nor by production of lymphokines such as IFN-gamma. Exogenous insulin-like growth factor-I (IGF-I), alone or in combination with GH, was without effect, making it unlikely that GH mediates its effects on monocytes via an autocrine/paracrine action of IGF-I. Monocytes specifically bound radiolabeled GH and contained mRNA for the GH receptor and, in some donors, the PRL receptor. Therefore, GH probably exerts its effects as a human macrophage-activating factor through either GH or PRL receptors, without requiring production of IGF-I.