bluuebunny/crossref_metadata_2025_split huggingface dataset:
Human microglial cell defense against Toxoplasma gondii. The role of cytokines.
Authors: Chao C C , Gekker G , Hu S , Peterson P K 
Published: December 2022

Abstract
Microglia may play an important role in host defense of the central nervous system against Toxoplasma gondii, and cytokines produced by these glial cells may participate in their antitoxoplasma activity. In our study, the antitoxoplasma activity of human fetal microglia was investigated. The RH strain of T. gondii multiplied readily in these glial cells. IFN-gamma/LPS-treated microglia limited (p &lt; 0.01) T. gondii growth by reducing entry of this parasite rather than intracellular multiplication. More than 90% of the antitoxoplasma activity of activated microglia was blocked (p &lt; 0.01) by neutralizing antibodies to TNF-alpha or IL-6 (but not to IL-1 or TGF-beta), suggesting that these proinflammatory cytokines play a role in the inhibitory process. Consistent with this hypothesis, treatment of microglia with TNF-alpha or IL-6 (in the presence or absence of IFN-gamma) inhibited (p &lt; 0.01), in a dose-dependent manner, T. gondii growth. Inasmuch as NGMA did not affect cytokine-mediated antitoxoplasma activity of microglia, nitric oxide appears not to be involved in this host defense function of human fetal microglia. Results of our study suggest that the host defense activity of human microglia against T. gondii is dependent primarily on the activating properties of IFN-gamma, TNF-alpha, and IL-6.
Human monocyte infection by Leishmania (Viannia) panamensis. Role of complement receptors and correlation of susceptibility in vitro with clinical phenotype.
Authors: Robledo S , Wozencraft A , Valencia A Z , Saravia N 
Published: December 2022

Abstract
Peripheral blood monocytes (PBMs) from healthy individuals who had experienced distinctive clinical outcomes after natural infection with Leishmania (Viannia) were evaluated in vitro with respect to susceptibility to infection by stationary phase promastigotes of L. (V). panamensis. Concomitantly, the role of complement receptors (CR) CR1 and CR3 in the attachment and entry of L. (V). panamensis into human monocytes was analyzed using mAbs to CR1 (CD35) and CR3 (CD11b) to inhibit competitively these early events in the host-parasite interaction. Cell adherence to fibronectin was examined to determine how modulation of CR activity affected the attachment and uptake of this parasite species. The human monocyte cell line U-937 was also evaluated and found to provide a reproducible control for L. (V). panamensis infection in vitro. Opsonization with fresh AB+ serum markedly enhanced uptake by both PBMs and U-937 cells, and the fluid phase blocking of CR1 and CR3 resulted in partial inhibition of attachment and/or internalization. Uptake rather than attachment was abrogated by antireceptor antibodies in PBMs from previously infected individuals, whereas attachment was diminished in PBMs from unexposed controls. Adherence of PBMs to fibronectin resulted in decreased infection. PBMs from persons who had experienced chronic disease 5 to 8.4 yr before these studies were significantly more susceptible to in vitro infection by L. (V). panamensis than PBMs from asymptomatically infected or control individuals based on the percentage of cells infected, the number of parasites per cell, and viability of intracellular parasites at 48 h postinfection. Neither blocking of CR nor modulation by fibronectin altered the pattern of susceptibility of PBMs from the different clinical groups. These findings provide evidence for the participation of CR in the infection of human monocytes by L. (V). panamensis and demonstrate a correlation between clinical phenotype and in vitro infection of PBMs cultured in the presence of autologous plasma before experimental infection.
Substance P increases neutrophil adhesion to bronchial epithelial cells.
Authors: DeRose V , Robbins R A , Snider R M , Spurzem J R , Thiele G M , Rennard S I , Rubinstein I 
Published: December 2022

Abstract
Polymorphonuclear neutrophils (PMNs) accumulate within the airways during acute and chronic bronchitis and can adhere to bronchial epithelium. Substance P (SP), a neuropeptide released from the primary afferent nerve endings, has been shown to have a proinflammatory effect on PMNs. To test the hypothesis that SP could modulate PMN bronchial epithelial cell adherence, bovine bronchial epithelial cells (BBECs) were isolated and cultured, and the capacity of SP to modulate PMN-BBEC adherence was evaluated. SP interacted with BBECs to induce an increase in PMN adhesion (14.7 +/- 1.2% vs 5.3 +/- 0.7% adherence, p &lt; 0.01). The effect of SP was both time- and dose-dependent with maximal responses at 6 h and 10(-10) M. The effect was reproduced by the carboxyl-terminal sequence of the molecule (SP 6-11). Importantly, pretreatment of the BBECs with the tachykinin SP receptor (NK1) antagonist, CP-96,345, significantly reduced the increase in adhesion induced by SP (p &lt; 0.01). Furthermore, treatment of the BBECs with antibodies against CD11a (LFA-1), CD11b (MAC-1), or ICAM-1 significantly decreased SP-induced adherence (p &lt; 0.01 all comparisons). Conversely, SP stimulation of PMN induced a dose-dependent, rapid (within 5 min) increase in adherence. This effect was also mediated by the carboxy end of the molecule and was decreased by CP-96,345, again suggesting that this effect was NK1 mediated. These data demonstrate the SP has the capacity for modulating PMN-BBEC interactions and suggest an important role for SP in modulating airway inflammation.
Neutrophil elicitation in the reverse passive Arthus reaction. Complement-dependent and -independent mast cell involvement.
Authors: Ramos B F , Zhang Y , Jakschik B A 
Published: December 2022

Abstract
Previous investigations in our laboratory have shown that mast cells play a significant role in the initiation of immune complex-mediated inflammation. Histamine, leukotrienes, and TNF released from mast cells are important mediators of early inflammatory processes. In the peritoneal reverse passive Arthus reaction, we observed a biphasic release of TNF. Mast cells were responsible for the first peak. The complement system is also known to be central to the expression of antibody-induced immune injury. Therefore, in this study, we investigated the significance of activated complement in regulating mast cell stimulation and neutrophil recruitment in the peritoneal reverse passive Arthus reaction. Mast cell degranulation and the release of TNF during the initiation of inflammation were blocked by decomplementation and C5 deficiency. Mast cell degranulation later in the reaction was complement-independent. Therefore, mast cells were activated in vivo in antibody-mediated injury by two different mechanisms, early in the reaction by complement and later by an unknown stimulus. Both mast cells and intact complement were also required for the full expression of neutrophil influx and release of TNF in the later phase. In fact, activated complement and mast cell mediators seemed to be the only factors necessary for the initiation of neutrophil recruitment. The findings significantly contribute to the understanding of the mechanisms involved in the induction of inflammatory processes in immune complex-mediated injury.
Effects of CD45 on NF-kappa B. Implications for replication of HIV-1.
Authors: Baur A , Garber S , Peterlin B M 
Published: December 2022

Abstract
Increased levels of replication of the HIV type 1 are observed after the activation of infected T cells through the TCR. However, anti-CD45 antibodies inhibit these effects in cells from infected individuals. In this study, we examined interrelationships between CD45 and HIV-1 further. We measured effects on the HIV-1 LTR in T cell lines that were stimulated with antibodies against CD45 and in those that lacked the expression of CD45 on their surfaces. First, anti-CD45 antibodies did not affect basal but decreased activated levels of expression from the HIV-1 LTR. Second, T cells, which lack CD45 and cannot signal via the TCR, supported higher levels of viral replication and gene expression. This was due to the presence of active NF-kappa B complexes in the nucleus of CD45- T cells. Additionally, infected T cells displayed lower levels of CD45 on their surfaces. Thus, CD45 plays an active role in the physiology of T cells and in the replication of HIV-1.
Effects of human T lymphocyte activation on inosine monophosphate dehydrogenase expression.
Authors: Dayton J S , Lindsten T , Thompson C B , Mitchell B S 
Published: December 2022

Abstract
Inosine monophosphate dehydrogenase (IMPDH) catalyzes the first step in the formation of guanine ribonucleotides from inosine monophosphate and the activity of this enzyme appears to be essential for cell proliferation. Inhibitors of IMPDH have been demonstrated to be effective immunosuppressive agents and to inhibit T cell activation in vitro. IMPDH activity results from the expression of two different genes (types I and II) that encode protein subunits of identical size with 84% amino acid identity. To determine the relative contribution of the expression of these two genes to T cell activation, we have examined the effects of T cell stimulation on IMPDH activity, mRNA levels, and protein. The stimulation of isolated peripheral blood CD28+ T cells with PMA and ionomycin causes a 15-fold increase in IMPDH activity over a 72-h period. This is associated with a 10-fold increase in type II mRNA levels at 48 h. Type I mRNA is expressed at very low levels in resting T cells, but increases 10-fold by 24 h after stimulation. The type I cDNA probe also detects a second larger mRNA species of 4.0 kb that is not detectable in a variety of normal tissues or in a panel of leukemic cell lines. RNase protection assays using RNA probes corresponding to the entire coding region of the type I enzyme reveal a single protected fragment, demonstrating that the 4.0-kb message is the result of alternate splicing in the 5' or 3' untranslated regions or the use of an alternative polyadenylation site. Western blot analysis demonstrates a concomitant increase in total IMPDH protein on T cell activation, although posttranslational modifications do not allow the distinction between type I and type II on isoelectric focusing gels. We conclude that the induction of both type I and type II IMPDH contribute significantly to the T cell proliferative response. Both enzymes therefore should be considered important targets for immunosuppressive therapy.
Functional distinctions between MRL-lpr and MRL-gld lymphocytes. Normal cells reverse the gld but not lpr immunoregulatory defect.
Authors: Ettinger R , Wang J K , Bossu P , Papas K , Sidman C L , Abbas A K , Marshak-Rothstein A 
Published: December 2022

Abstract
Homozygosity for either of the autosomal recessive mutations, lpr or gld, confers an autoimmune syndrome characterized by massive lymphoid hyperplasia and extensive autoantibody production. Despite the similarities in disease progression, functional distinctions in these genetic defects have been observed in bone marrow transplantation studies. To elucidate the mechanisms responsible for the aberrant immune phenotype of these strains, we analyzed interactions between normal T cells and T cells from the two autoimmune strains with regard to their in vitro responses to autologous and allogeneic stimuli and in an in vivo bone marrow transplantation model. Despite similar propensities for lpr and gld T cells to spontaneously proliferate in vitro in response to autologous class II Ag, a dramatic difference in their immunoregulatory properties was found when mixtures of normal and autoimmune CD4+ responder cells were challenged with an allogeneic stimulus. T cells from the lpr, but not gld, mice blocked the normal T cell component of the response. In vivo, the ability of lpr stem cells to trigger a wasting syndrome when transplanted into normal irradiated recipients could not be prevented by including normal stem cells in the inoculum; however, the ability of gld stem cells to transfer the gld-lymphoproliferative syndrome to normal recipients could be prevented with the addition of normal stem cells. These results support a model whereby the lpr and gld strains are defective in reciprocal components of a down-regulatory signaling pathway; failure to express either the functional receptor or ligand leads to a dysregulated immune system resulting in systemic autoimmunity. Based on the linkage between the lpr locus and Fas Ag expression, we propose that the failure of lpr mice to express Fas results in overproduction of Fas-ligand, whereas gld mice fail to make either the Fas-ligand or a functionally related protein, presumably belonging to the TNF family.
T cell recognition of somatically-generated Ab diversity.
Authors: Eyerman M C , Wysocki L 
Published: December 2022

Abstract
During an immune response, specific Abs and B cells that are infrequently represented in the preimmune repertoire become amplified to abundance. Novel structures are also created through the physiological process of somatic hypermutation in Ab genes. This presents a challenge for T cell self-tolerance, because many potential V region epitopes are either rare or nonexistent during the maturation of the T cell repertoire in the thymus. To explore the potential for T cell recognition of Ab V regions, we immunized A/J mice with two somatically mutated mAbs (mAb36-71 and mAb45-49) derived from A/J mice and produced 13 mAb-specific T cell hybridomas. All of the T cell hybridomas express alpha beta receptors and CD4, and their responses to the mAb are restricted in the context of class II MHC glycoproteins. In presentation studies with fixed APCs and whole or trypsinized mAb, we found that processing of the mAb is necessary for stimulation of the T cell hybridomas. Therefore each of the hybridomas recognizes the mAbs in a conventional class II MHC-restricted manner. We also found that each of the 13 T cell hybridomas responded to the somatically-mutated light chains of mAb45-49 and mAb36-71. In contrast, none of them responded to unmutated versions of the same light chains. These results show that the T cell repertoire includes members able to recognize syngeneic Abs containing somatic mutations that were physiologically acquired during the course of an immune response.
Activated CD4+ T cells induce CD40-dependent proliferation of human B cell precursors.
Authors: Renard N , Duvert V , Blanchard D , Banchereau J , Saeland S 
Published: December 2022

Abstract
Anti-CD3-activated human CD4+ T cell clones were found to induce proliferation of CD10+, CD19+, surface(s) Ig- B cell precursors (BCP) isolated from human fetal bone marrow. The great majority of the B lineage cells recovered in cocultures of BCP and activated T cells displayed a BCP phenotype (Ig- or cytoplasmic mu+ and kappa/lambda-), including most of the cycling cells, indicating that the cultures do not favor a transition to mature B cells. Supernatants of activated T cells were ineffective in inducing BCP proliferation, indicating the necessity of close association with stimulator cells. In line with this finding, the CD40 molecule was found to represent an important component of the cocultures, as BCP proliferation was strongly inhibited by soluble anti-CD40 antibody. In addition, CD4+ T cell clones from a hyper-IgM patient expressing a truncated CD40 ligand (CD40-L) failed to induce BCP proliferation. Finally, a combination of cytokines (IL-2, IL-3, IL-7, and IL-10) enhanced the observed T cell-dependent BCP proliferation, but could not substitute for the deficient CD40-L. Taken together, our data demonstrate that CD4+ T cells exert a stimulatory effect on in vitro B human lymphopoiesis via the CD40 pathway. The present results suggest that T cells may play an important role in regulating B cell ontogeny in the bone marrow.
In vivo cytokine expression in the thymus. CD3high human thymocytes are activated and already functionally differentiated in helper and cytotoxic cells.
Authors: Vandekerckhove B A , Bárcena A , Schols D , Mohan-Peterson S , Spits H , Roncarolo M G 
Published: December 2022

Abstract
CD4 and CD8 are expressed on mutually exclusive T cell populations that can recognize peptides bound to class II and class I MHC Ags, respectively. These populations have different functions and are different in their capacity to produce cytokines. In this paper we demonstrate that this functional differentiation occurs at the CD3low- CD3high transitional stage: single positive mature CD4+ thymocytes express IL-2 mRNA in vivo, whereas CD8+ thymocytes primarily express perforin. IL-2, perforin, and IFN-gamma mRNAs were almost absent in CD4+CD8+ CD3low but were clearly detectable in CD4+CD8+ CD3high cells, indicating that these genes are induced at the CD3low- CD3high transitional stage. In contrast, IL-4 mRNA levels were highest in the precursor cells but dropped sharply at the CD3low-CD3high transitional stage. These data are consistent with and link two earlier observations, i.e., that activation occurs at the CD3low-CD3high transition and that functional differentiation in helper and cytotoxic cells is already accomplished in the single positive thymocytes. This activation may reflect positive selection and concomitant functional differentiation into helper and cytotoxic T cells.
Alternatively spliced transcripts of the human complement C2 gene.
Authors: Cheng J , Volanakis J E 
Published: December 2022

Abstract
To investigate the possible presence of alternatively spliced C2 gene transcripts, we amplified mRNA from HepG2 cells by reverse transcription-PCR using primers derived from the 5' and 3' untranslated regions of the C2 mRNA. Cloning of the resulting products revealed the presence of four novel C2 mRNA size variants. Nucleotide sequencing indicated that the variant mRNAs were probably derived through differential splicing of C2 gene transcripts. Specifically, nucleotide sequence deletions in the four variant mRNAs could be attributed to splicing out of: 1) exons 2 and 3; 2) exon 3; 3) exon 17; and 4) exons 6 and 7 and the 5' region of exon 18. The results were confirmed by RNase protection assays using HepG2 mRNA. Inspection of the nucleotide and the deduced amino acid sequences indicated that in the first two variants the alternative splicing did not affect the C2 open reading frame. In the other two variants, frameshifts in exon 18 resulted in termination codons up- or downstream of the authentic termination codon. All four variants C2 mRNAs were capable of encoding truncated C2 proteins, and were detected by reverse transcription-PCR not only in HepG2 cells but also in human liver, U937, and U105-MG cells. The latter analyses indicated the presence of an additional C2 mRNA variant lacking the region encoded by exon 6.
Macrophages from schistosomal egg granulomas induce unresponsiveness in specific cloned Th-1 lymphocytes in vitro and down-regulate schistosomal granulomatous disease in vivo.
Authors: Flores Villanueva P O , Harris T S , Ricklan D E , Stadecker M J 
Published: December 2022

Abstract
We previously have proposed that accessory cells from individuals infected with schistosomiasis induce unresponsiveness in specific Th-1 lymphocytes resulting in the immunologic down-regulation of egg-induced granulomatous inflammation characteristically seen in this disease. We now show that macrophages isolated from schistosomal egg granulomas (GM) fail to serve as stimulatory APC for cloned, murine schistosomal egg Ag (SEA)-specific, CD4+, Th-1-type lymphocytes, while being able to stimulate Th-2-type responses. Instead, GM render Th-1 cells unresponsive to restimulation. Based on these findings, we tested two approaches to down-regulate the granulomatous inflammation associated with a schistosomal challenge infection. First, active ectopic granuloma induction in response to Schistosoma mansoni eggs, but not to Ascaris lumbricoides eggs, resulted in a significant reduction of granulomatous disease in vivo, as well as in the inhibition of specific proliferation of mesenteric lymph node cells in vitro. Second, passive administration of purified GM, but not of normal peritoneal cells (PC), resulted, similarly, in significant reduction of granuloma size in vivo and specific lympho-proliferation in vitro. Moreover, cytokine analysis of supernatants from stimulated lymph node cells disclosed that the Th-1-derived cytokine IL-2 decreased to undetectable levels, at the same time as the Th-2-derived cytokines IL-4 and IL-10 increased, in animals receiving GM, in contrast to those receiving PC or no cells. These findings are consistent with the interpretation that accessory cells such as GM induce unresponsiveness in specific Th-1 cells that, in turn, results in the down-regulation of granulomatous schistosomal disease and its in vitro correlates.
Neutralization of IL-12 decreases resistance to Listeria in SCID and C.B-17 mice. Reversal by IFN-gamma.
Authors: Tripp C S , Gately M K , Hakimi J , Ling P , Unanue E R 
Published: December 2022

Abstract
Interleukin-12 (IL-12) is necessary for the production of IFN-gamma by NK cells during the generation of innate immunity and by T cells for the development of the Th1 response during specific cell-mediated immunity. Here we demonstrate that the endogenous production of IL-12 is critical to the survival of both immunocompromised SCID mice and normal C.B-17 control mice during a primary infection with Listeria monocytogenes. When IL-12 is neutralized in vivo, both strains of mice die at a normally sublethal dose of Listeria. Anti-IL-12 antibody-treated mice showed a decrease in macrophage I-Ad expression and an increase Listeria burden in the spleen. Furthermore, as has been demonstrated in vitro, these effects of IL-12 in vivo were predominantly regulated through the production of IFN-gamma. Administration of IFN-gamma simultaneously with neutralizing antibodies to IL-12 restored macrophage I-Ad expression, limited the spread of the infection, and resulted in the survival of SCID mice. Thus, IL-12 is critical for resistance to infection with Listeria monocytogenes, and this resistance is mediated through stimulation by IL-12 of IFN-gamma production. Concomitant experiments confirmed that anti-TNF antibodies also resulted in uncontrolled infection and a decrease in macrophage I-Ad expression. However, administration of IFN-gamma restored the levels of I-Ad in macrophages but did not limit Listeria growth.
Induction of macrophage growth by advanced glycation end products of the Maillard reaction.
Authors: Yui S , Sasaki T , Araki N , Horiuchi S , Yamazaki M 
Published: December 2022

Abstract
We previously showed that negatively-charged phospholipids, acetylated low density lipoprotein (LDL) and oxidized LDL, which are known to be taken up by macrophages via the scavenger receptor for modified LDLs, were able to induce the growth of peripheral macrophages in vitro. The present study demonstrated the macrophage growth-stimulating activity of the ligands for another macrophage receptor for advanced glycation end products (AGE) of the Maillard reaction. Experiments with murine macrophages showed that significant cell growth was induced by AGE-modified proteins such as bovine serum albumin (AGE-BSA) and AGE-human hemoglobin. The capacity of AGE-BSA to induce macrophage growth was completely blocked when cells were cultured with the mAb against granulocyte/macrophage CSF (GM-CSF). Moreover, PCR analysis revealed that AGE-BSA induced the expression of mRNA of GM-CSF. These data suggest that the macrophage AGE receptor may play an active role not only in phagocytic elimination of AGE-proteins but also induction of the growth of macrophages.