bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differential Effect of Anti-B7-1 and Anti-M150 Antibodies in Restricting the Delivery of Costimulatory Signals from B Cells and Macrophages
Authors: Agrewala Javed N. , Suvas Susmit , Verma Rakesh K. , Mishra Gyan C. 
Published: December 2022

AbstractB7-1 and M150 are potent costimulatory molecules expressed on B cells and macrophages. We have examined the capacity of Abs against B7-1 and M150 in differentially inhibiting the costimulatory signals delivered by macrophages and B cells to OVA-specific CD4+ T cells. The anti-B7-1 Ab significantly blocked the proliferation of Th cells, MLR, T cell help to B cells, and secretion of IFN-γ when B cells were used to provide costimulation, but not when macrophages were used. In contrast, anti-M150 Ab significantly decreased the proliferation of Th cells, MLR, and production of IFN-γ, when macrophages were utilized to provide costimulatory signals, but not when B cells were used as APC. However, when macrophages activated with IFN-γ were used as a source of costimulation, like anti-M150 Ab, Ab to B7-1 also down-regulated the activation of Th cells. The significance of this finding is that M150 is a potent first costimulatory signal for initiating proliferation and secretion of IFN-γ and providing cognate help for B cells by Th cells when the macrophage is used as an accessory cell. M150-induced IFN-γ production induces the expression of B7-1 on the surface of macrophages, which then delivers a second cosignal for Th cells. B7-1 works efficiently when B cell provides cosignal. Both of the molecules promote Th1 activity, as evidenced by the inhibition of the secretion of IFN-γ but not IL-4 by Th cells with anti-M150 and B7-1 Abs.
Class I-Restricted Alloreactive Cytotoxic T Lymphocytes Recognize a Complex Array of Specific MHC-Associated Peptides
Authors: Wang Wei , Man Stephen , Gulden Pamela H. , Hunt Donald F. , Engelhard Victor H. 
Published: December 2022

AbstractA major issue in understanding alloreactive T cell responses is whether the Ags recognized reside in allogeneic MHC proteins themselves regardless of the structure of the associated peptides or whether specific peptides presented by allogeneic MHC proteins determine each epitope. We developed HLA-A*0201-specific alloreactive human CD8+ CTL lines and clones to address this issue. Acid treatment of HLA-A*0201+ target cells resulted in the loss of Ab-defined epitopes as well as recognition by all alloreactive CTL. In the presence of brefeldin A, no class I molecules were re-expressed at the surface of the acid-treated cells. Addition of a mixture of synthetic peptides corresponding to known, naturally processed, HLA-A*0201-associated peptides together with exogenous human β2m restored binding by specific Ab but not recognition by alloreactive CTL. However, addition of a more complex mixture of peptides directly extracted from HLA-A*0201 reconstituted CTL recognition. This demonstrates that these alloreactive CTL recognize specific peptides and not a common peptide-dependent conformation of HLA-A*0201. Reverse phase HPLC fractionation of the extracted peptides resulted in the loss of recognition by CTL lines from three individuals. This was not due to the loss of specific peptide species because repooling of the HPLC fractions led to a recovery of recognition. Furthermore, three HLA-A*0201-alloreactive CTL clones recognized single distinct peptide peaks from the same HPLC fractionation. These data suggest that the epitopes recognized in allogeneic responses to HLA-A*0201 are complex, and the response is a result of recognition of multiple unique peptide-MHC complexes.
Role of CD38 and Its Ligand in the Regulation of MHC-Nonrestricted Cytotoxic T Cells
Authors: Cesano Alessandra , Visonneau Sophie , Deaglio Silvia , Malavasi Fabio , Santoli Daniela 
Published: December 2022

AbstractHuman CD38 is a type II transmembrane glycoprotein that regulates lymphocyte adhesion, proliferation, and cytokine production. The mAb Moon-1 recognizes a ligand for CD38 (CD38L) and specifically inhibits CD38-mediated cell adhesion. To analyze the role of CD38 and its ligand in MHC-nonrestricted T cell activation, we examined the effects of Moon-1 and the anti-CD38 mAb IB4 on the effector functions of the IL-2-dependent T cell line TALL-104 (CD3/TCR-αβ+, CD8+, CD56+) and of LAK cells (90% CD3+). TALL-104 cells were almost 100% reactive with both mAbs, whereas the reactivity of LAK cells for IB4 and Moon-1 ranged from 10 to 60% among different donors. From 78 to 94% of the cytotoxic CD8+/CD56+ LAK subset was CD38L+. Like mAb OKT3 (anti-CD3), and at variance with IB4, Moon-1 drastically enhanced the cytotoxicity of TALL-104 and CD8+ LAK cells against a resistant tumor target. Granule exocytosis did not appear to play a role in Moon-1-induced cytotoxicity. Moreover, neither IB4 nor Moon-1 induced [Ca2+]i mobilization in LAK and TALL-104 cells. Whereas stimulation of CD3 and CD38 resulted in a dramatic induction of cytokine (granulocyte-macrophage-CSF, IFN-γ, TNF-α, and TNF-β) release by both TALL-104 and LAK cells, ligation of CD38L was not followed by cytokine production in TALL-104 cells. Thus, cytotoxicity and cytokine release are independently regulated, at least in this system. These data demonstrate that CD38 and its ligand can regulate some T cell functions using signaling pathways distinct from those of CD3.
Differential Expression of the Melatonin Receptor in Human Monocytes
Authors: Barjavel Marc J. , Mamdouh Zahra , Raghbate Nadjibe , Bakouche Ouahid 
Published: December 2022

AbstractEarlier studies have shown that the pineal hormone melatonin activates human monocytes. It is reported here that melatonin induces the secretion of IL-1, IL-6, and TNF in fresh and 1-day in vitro cultured monocytes that also express the melatonin receptor (Kd = 270 ± 60 pM; 42,000–48,000 receptors/cell). However, when monocytes were cultured in vitro for 2 days, the number of receptors decreased to 11,000 receptors/cell, with the same Kd. LPS activation of fresh or 1-day cultured monocytes did not result in any increase in melatonin receptor number. LPS activation of 2-day cultured monocytes led to an increase in the number of melatonin receptors, from 11,000 receptors/cell to the plateau of 42,000 to 48,000 receptors/cell. The loss of receptors by 2-day cultured monocytes was not irreversible. Melatonin did not induce the release of IL-1, TNF, or IL-6 in monocytes cultured in vitro for 3 days and for up to 15 days, and these long time cultured monocytes did not express the melatonin receptors even after activation by LPS. The loss of melatonin receptors by monocytes cultured in vitro for 3 days and for up to 15 days was irreversible. Therefore, it is shown for the first time that human monocytes express melatonin receptors. Furthermore, human monocytes express melatonin receptors differentially depending on their state of maturation, and it appears that in vitro monocyte differentiation and maturation negatively affect human monocyte melatonin receptor expression.
VH Mutant Rabbits Lacking the VH1a2 Gene Develop a2+ B Cells in the Appendix by Gene Conversion-Like Alteration of a Rearranged VH4 Gene
Authors: Sehgal Devinder , Mage Rose G. , Schiaffella Enrico 
Published: December 2022

AbstractWe investigated the molecular basis for the appearance of VHa2 allotype-bearing B cells in mutant Alicia rabbits. The mutation arose in an a2 rabbit; mutants exhibit altered expression of VH genes because of a small deletion encompassing VH1a2, the 3′-most gene in the VH locus. The VH1 gene is the major source of VHa allotype because this gene is preferentially rearranged in normal rabbits. In young homozygous ali/ali animals, the levels of a2 molecules found in the serum increase with age. In adult ali/ali rabbits, 20 to 50% of serum Igs and B cells bear a2 allotypic determinants. Previous studies suggested that positive selection results in expansion of a2 allotype-bearing B cells in the appendix of young mutant ali/ali rabbits. We separated appendix cells from a 6-wk-old Alicia rabbit by FACS based on the expression of surface IgM and a2 allotype. The VDJ portion of the expressed Ig mRNA was amplified from the IgM+ a2+ and IgM+ a2− populations by reverse transcriptase-PCR. The cDNAs from both populations were cloned and sequenced. Analysis of these sequences suggested that, in a2+ B cells, the first D proximal functional gene in Alicia rabbits, VH4a2, rearranged and was altered further by a gene conversion-like mechanism. Upstream VH genes were identified as potential gene sequence donors; VH9 was found to be the most frequently used gene donor. Among the a2− B cells, y33 was the most frequently rearranged gene.
Activation-Induced T Cell Death ExacerbatesTrypanosoma cruziReplication in Macrophages Cocultured with CD4+ T Lymphocytes from Infected Hosts
Authors: Nunes Marise P. , Andrade Regis M. , Lopes Marcela F. , DosReis George A. 
Published: December 2022

AbstractActivation-induced cell death (AICD) of CD4+ T lymphocytes was described in infection with Trypanosoma cruzi, but a role for AICD in modulating parasite spread in host cells has not been investigated. In this study, replication of T. cruzi in vitro in murine macrophage (Mφ) monolayers was investigated. Long term (5 to 13 day) replication of infective (trypomastigote) T. cruzi forms was blocked by supernatants from activated (anti-TCR) CD4+ T cells of infected mice or by rIFN-γ. However, when CD4+ T cells from infected mice were cocultured with Mφ and activated by anti-TCR, marked exacerbation of trypomastigote growth in Mφ ensued. The deleterious effect required contact between T cells and infected Mφ. Both anti-Fas and TCR activation killed a proportion of CD4+ T cells. Ly-6 activation did not induce AICD and did not exacerbate parasite growth. However, Fas-mediated killing of T cells before Ly-6 activation led to exacerbated parasite growth. Although a minor population, Fas-susceptible cells were the major source of IFN-γ production by activated T cells. Addition of a neutralizing anti-Fas ligand antibody blocked 50 to 60% of CD4+ T cell AICD and reduced trypomastigote growth in T/Mφ cocultures stimulated by anti-TCR. The results demonstrate that in CD4+ T cells from infected mice, the onset of AICD selectively ablates IFN-γ production and up-regulates parasite replication in Mφ in vitro. These findings suggest a deleterious role for AICD in T. cruzi infection.
Pre-Exposure to Oxidative Stress Decreases the Nuclear Factor-κB-Dependent Transcription in T Lymphocytes
Authors: Lahdenpohja Nina , Savinainen Kimmo , Hurme Mikko 
Published: December 2022

AbstractReactive oxygen species (ROS) are used as signaling molecules in T cell activation. One of the main targets of ROS is the transcription factor nuclear factor-κB (NF-κB). NF-κB-dependent transcription is inhibited by antioxidants, and the activation is induced or potentiated by ROS. However, chronic oxidative stress is known to reduce the activation of T cells and NF-κB. To analyze these phenomena in more detail, we have exposed Jurkat T cells in vitro to oxidative stress (H2O2) at various times before or simultaneously with signals known to activate NF-κB (phorbol dibutyrate (PDBu) and TNF). Simultaneously applied H2O2 strongly potentiated the PDBu- or TNF-induced transcriptional activity of NF-κB. In contrast to this, H2O2 given 3 to 20 h before the activating signal reduced NF-κB-dependent transcriptional activity. This was not due to the oxidation-induced modification of NF-κB; cytoplasmic NF-κB was able to bind to DNA after dissociation from IκBα by detergent treatment. H2O2 pre-exposure effectively inhibited the PDBu- or TNF-induced phosphorylation and degradation of IκBα, but H2O2 given simultaneously with PDBu or TNF enhanced the degradation. Oxidative stress was also followed by a strongly decreased ability to form intracellular ROS. Taken together, these data indicate that IκBα phosphorylation is the target of action of ROS, and as the ROS-forming capacity is weaker after chronic oxidative stress, IκBα is not effectively phosphorylated and degraded, thus leading to decreased NF-κB-dependent transcription.
Factors Involved in Regulating Primary and Secondary Immunity to Infection withHistoplasma capsulatum: TNF-α Plays a Critical Role in Maintaining Secondary Immunity in the Absence of IFN-γ
Authors: Zhou Ping , Miller Giorgina , Seder Robert A. 
Published: December 2022

AbstractPrimary infection to Histoplasma capsulatum often results in a self-limited upper respiratory infection in humans; however, in immunocompromised hosts, disseminated infection can occur through reactivation of a previous infection. Since disseminated histoplasmosis has emerged as a difficult clinical entity to treat in individuals infected with HIV, it was of interest to study the mechanisms involved in maintaining an effective memory immune response. It has been previously shown in a murine model of disseminated histoplasmosis that IL-12, IFN-γ, and TNF-α were important factors in mediating primary protection. To study whether these and other factors were involved in maintaining a protective immune response following secondary infection, normal C57BL/6 mice were first infected with a sublethal dose of H. capsulatum (1 × 105) and then reinfected 3 wk later with a lethal dose of H. capsulatum (6 × 105). Under these conditions, all mice developed an effective immune response with sterilizing immunity. Moreover, normal C57BL/6 mice treated with neutralizing Abs against either IL-12, TNF-α, or IFN-γ, depleted of neutrophils or treated with aminoguanidine at the time of reinfection, maintained an effective immune response. The ability of animals to survive a secondary infection in the absence of IFN-γ was verified by showing that IFN-γ−/− mice previously immunized with H. capsulatum and treated with amphotericin B at the time of primary infection had prolonged survival following reinfection with a normally lethal dose. It was further shown that enhancement of TNF-α production in IFN-γ−/− mice was the major mechanism by which these mice were effective in controlling secondary infection.
Immune Response Against Large Tumors Eradicated by Treatment with Cyclophosphamide and IL-12
Authors: Tsung Kangla , Meko Jennifer B. , Tsung Ying L. , Peplinski Gary R. , Norton Jeffrey A. 
Published: December 2022

AbstractPrevious studies have demonstrated eradication of small (4–8 mm) established murine MCA207 sarcomas by treatment with systemic IL-12. Analysis of the mechanism has revealed a cellular and molecular immune response at the tumor typical of a Th1 cell-mediated, macrophage-effected, delayed-type hypersensitivity (DTH) response. In the current study we investigate the immune response against long term established, large MCA207 tumors induced by combined treatment with IL-12 and cyclophosphamide (Cy), an agent known to potentiate the DTH response. Our results demonstrate that s.c. large MCA207 tumors (15–20 mm) that are refractory to treatment by either IL-12 or Cy alone can be completely eradicated by the combination of Cy and IL-12. IL-12 is apparently the only cytokine capable of mediating tumor eradication, and the effect is dependent on IFN-γ. The contribution of Cy is probably due to immunopotentiation of DTH rather than to direct cytotoxicity to the tumor. The regression of these large tumors takes &gt;4 wk and, in many cases, is self-sustained, in that little or no additional IL-12 is needed beyond the initial week of administration. Analysis of the cellular and molecular events at the tumor site suggests that the mechanism is a Th1-mediated antitumor immune response.
Novel Immunoregulatory B Cell Pathways Revealed bylpr-+ Mixed Chimeras
Authors: Sobel Eric S. , Kakkanaiah Vellalore N. , Schiffenbauer Joel , Reap Elizabeth A. , Cohen Philip L. , Eisenberg Robert A. 
Published: December 2022

Abstractlpr, a murine mutation of the Fas apoptosis receptor, causes lymphadenopathy and autoantibody production, with lymphadenopathy primarily due to a population of CD4−CD8−B220+ T cells. Previous in vivo experiments, in which lpr and normal bone marrow cells were coinfused into lpr hosts, have demonstrated that only T cells of lpr origin accumulated abnormally and only B cells of lpr origin produced autoantibodies. Moreover, in these chimeras, B cells of normal origin were unable to respond to conventional, T cell-dependent exogenous Ag. To address the role of lpr B cells in regulation of lpr autoimmunity, we have prepared lpr-+ mixed chimeras and selectively eliminated lpr B cells using allele-specific, mAb treatment, thus allowing normal B cells to develop in an environment with lpr T cells. From these data, we arrived at four major conclusions: 1) Compared with control-treated chimeric mice, lpr B cell-depleted mice had greatly reduced total lymph node cell counts; 2) the T cells were derived equally from normal and lpr donors, and the percentage of lpr-derived CD4−CD8− T cells was greatly reduced; 3) despite the presence of the remaining lpr T cells, no autoantibodies were produced by the normal derived B cells; and 4) lpr T cells without lpr B cells were unable to prevent a normal B cell response to conventional Ag. These data demonstrate that B cells can play a critical and expansive regulatory role, not only for T cells, but for other B cells as well.
Mechanisms of Acquired Thymic Tolerance In Vivo: Intrathymic Injection of Antigen Induces Apoptosis of Thymocytes and Peripheral T Cell Anergy
Authors: Chen Wanjun , Sayegh Mohamed H. , Khoury Samia J. 
Published: December 2022

AbstractIntrathymic injection of Ag induces Ag-specific tolerance in several clinically relevant experimental autoimmune and transplantation models. However, the exact mechanisms of acquired thymic tolerance in vivo remain unclear. We investigated the mechanisms of acquired thymic tolerance in mice that are transgenic for the TCR specific for peptide 323-339 of OVA. Intrathymic injection of OVA leads to apoptosis of thymocytes starting as early as 3 h after injection and persisting up to 7 days. Double positive thymocytes undergo apoptosis earlier than single positive thymocytes, and significantly higher percentages of double positive thymocytes ultimately die as compared with single positive cells. Apoptotic cells show decreased surface expression of CD4. In the periphery, T cells from intrathymically injected animals had suppressed proliferation and IL-2 production to OVA compared with T cells from control Ag-injected mice. We conclude that intrathymic injection of Ag induces apoptosis of immature thymocytes and a subpopulation of mature thymocytes and induces prolonged anergy in peripheral T cells in vivo. Understanding the mechanisms of acquired thymic tolerance may lead to development of novel clinical strategies to prevent autoimmune disease and transplant rejection.
A Physiologic Role of Bcl-xL Induced in Activated Macrophages
Authors: Okada Seiji , Zhang Hong , Hatano Masahiko , Tokuhisa Takeshi 
Published: December 2022

AbstractActivated macrophages produce nitric oxide (NO) that is an important effector molecule for their antimicrobial and antitumor activities. Since this NO is also toxic for themselves, they have self-defense mechanisms. To elucidate the mechanisms in a physiologic condition, expression of bcl-2 family genes were examined in peritoneal macrophages and RAW264 macrophage cell line activated with IFN-γ and LPS. Bcl-xL, but not bcl-2 and bax mRNA, was highly inducible within 3 h after stimulation. The induction required new protein synthesis, but was independent of effects of synthesized NO. Since activated RAW264 were more resistant to NO-induced apoptosis mediated by the exposure to S-nitroso-N-acetyl-penicillamine (SNAP) than nonactivated RAW264, the inducible Bcl-xL may play a role in the protection from NO toxicity. To confirm the protective function, RAW264 were stably transfected with bcl-xL. Those transfectants activated with IFN-γ and LPS appeared highly resistant to NO-induced cell death detected within 24 h after stimulation, although their NO production was similar to those of parental RAW264 and neomycin control-transfected cells. Furthermore, bcl-xL transfectants displayed substantial protection from SNAP-induced apoptosis. These results establish a link between self-defense to the synthesized NO and the induction of Bcl-xL in activated macrophages.
Suppression of Fas/APO-1-Mediated Apoptosis by Mitogen-Activated Kinase Signaling
Authors: Holmström Tim H. , Chow Sek C. , Elo Iina , Coffey Eleanor T. , Orrenius Sten , Sistonen Lea , Eriksson John E. 
Published: December 2022

AbstractJurkat T cells undergo rapid apoptosis upon stimulation of the Fas/APO-1 (CD95) receptor. We examined the role of the mitogen-activated protein kinase (MAPK) cascade as a negative regulator of Fas-mediated apoptosis. To this end, we used both physiologic and artificial activators of MAPK, all of which activate MAPK by distinct routes. MAPK activity could be efficiently elevated by two T cell mitogens, the lectin PHA and an agonistic Ab to the T cell receptor complex as well as by the type 1 and 2A phosphatase inhibitor, calyculin A, and the protein kinase C-activating phorbol ester, tetradecanoyl phorbol acetate. All these treatments were effective in preventing the characteristic early and late features of Fas-mediated apoptosis, including activation of caspases. Our results indicate that the elevated MAPK activities intervene upstream of caspase activation. The degree of MAPK activation by the different stimuli used in our study corresponds well to their potency to inhibit apoptosis, indicating that MAPK activation serves as an efficient modulator of Fas-mediated apoptosis. The role of MAPK in modulation of Fas-mediated apoptosis was further corroborated by transient transfection with constitutively active MAPK kinase, resulting in complete inhibition of the Fas response, whereas transfection with a dominant negative form of MAPK kinase had no effect. Furthermore, the apoptosis inhibitory effect of the MAPK activators could be abolished by the specific MAPK kinase inhibitor PD 098059. Modulation of Fas responses by MAPK signaling may determine the persistence of an immune response and may explain the insensitivity of recently activated T cells to Fas receptor stimulation.
Age-Dependent Appearance of NK1.1+ T Cells in the Livers of β2-Microglobulin Knockout and SJL Mice
Authors: Murakami Masao , Paul William E. 
Published: December 2022

Abstract
NK1.1+ T cells, a specialized set of T cells that recognize CD1, are reportedly absent in young β2-microglobulin-deficient (β2m-knockout (KO)) and SJL mice. In this study, we show that a significant number of NK1.1+ T cells exist in the livers of older β2m-KO and SJL mice, and that the number of liver NK1.1+ T cells increases as the animals age. The surface phenotypes of liver NK1.1+ T cells from β2m-KO and SJL mice were similar to NK1.1+ T cells from C57BL/6 mice, except that the bulk of these cells were CD4−CD8−. After anti-CD3 injection in vivo, the cells promptly expressed IL-4 mRNA just as NK1.1+ T cells did in normal mice. Using L cells expressing CD1, liver NK1.1+ T cells from both β2m-KO and SJL mice were stimulated to proliferate, although to a lesser degree than were such cells from C57BL/6 mice. Our studies show that some NK1.1+ T cells accumulate in the livers of older β2m-KO and SJL mice, and that they appear to have functional properties similar to “normal” NK1.1+ T cells.