bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interaction of CTLA-4 with the clathrin-associated protein AP50 results in ligand-independent endocytosis that limits cell surface expression.
Authors: Chuang E , Alegre M L , Duckett C S , Noel P J , Vander Heiden M G , Thompson C B 
Published: December 2022

Abstract
CTLA-4 is a lymphocyte cell surface receptor expressed by activated T cells that functions to down-regulate T cell responses induced by TCR and CD28 stimulation. Since CTLA-4 competes with CD28 for binding to the common ligands B7-1 and B7-2, the level of CTLA-4 surface expression is likely to play an important role in its ability to inhibit CD28-dependent T cell activation. The factors that regulate these levels are poorly understood. Recent studies have revealed that following T cell activation, the majority of CTLA-4 is localized intracellularly rather than on the cell surface, and surface CTLA-4 is rapidly reinternalized. In this study, we investigate the molecular mechanism underlying the rapid clearance of CTLA-4 from the cell surface. The data demonstrate that cell surface CTLA-4 is endocytosed into clathrin-coated vesicles even in the absence of ligand. The targeting of CTLA-4 to clathrin-coated vesicles is mediated by the clathrin-associated adaptor complex AP-2. The cytoplasmic domain of CTLA-4 was found to specifically bind to AP50, the medium chain subunit of AP-2 in both yeast two-hybrid and coimmunoprecipitation assays. The interaction requires the peptide sequence 199-GVYVKM-204 in the cytoplasmic tail of CTLA-4. Mutation of the CTLA-4 amino acid residue Y201 abrogates the interaction with AP50, resulting in the accumulation of CTLA-4 at the cell surface. Together these data suggest that the interaction of CTLA-4 with AP50 plays an important role in regulating the cell surface expression of CTLA-4.
Direct MHC class I complementary DNA transfer to thymus induces donor-specific unresponsiveness, which involves multiple immunologic mechanisms.
Authors: Knechtle S J , Wang J , Graeb C , Zhai Y , Hong X , Fechner J H , Geissler E K 
Published: December 2022

Abstract
Our purposes were 1) to determine whether direct transfer of cDNA encoding allogeneic MHC class I Ag to the rat thymus would be capable of inducing donor-specific unresponsiveness and 2) to study the immunologic mechanism of this effect. Plasmid DNA encoding donor strain (ACI-RT1.Aa) MHC class I Ag was directly injected into Lewis (RT1(l)) rat recipient thymus 7 to 10 days before ACI liver transplantation. A single dose of anti-lymphocyte serum was given i.p. on the day of thymic injection. Rats injected intrathymically with plasmid DNA and treated with anti-lymphocyte serum demonstrated prolonged survival in 9 of 13 rats (&gt;100 days). PCR was used to demonstrate that RT1.Aa cDNA was expressed in thymus transiently and later appeared in spleen. CTL limiting dilution assays showed that CTL precursor frequency was decreased in tolerant liver recipients. To test the hypothesis of clonal deletion vs anergy, CTL limiting dilution assays cultures were restimulated with donor cells and IL-2 to reverse anergy. Restimulation caused CTL precursor frequency to return to near normal in only one of five tolerant rats, suggesting clonal deletion or a dense anergic state. Passive transfer of splenocytes from tolerant rats to naive recipients prolonged cardiac allograft survival, suggesting that suppressor-type cells may also contribute to thymic tolerance in our model. In summary, our data suggest that donor MHC class I Ag expressed in thymus by direct DNA injection, followed by liver allografting, results in donor-specific unresponsiveness. The mechanism of this effect is complex, involving multiple immunologic mechanisms.
In vivo mechanism by which leflunomide controls lymphoproliferative and autoimmune disease in MRL/MpJ-lpr/lpr mice.
Authors: Xu X , Blinder L , Shen J , Gong H , Finnegan A , Williams J W , Chong A S 
Published: December 2022

Abstract
Two activities have been identified for the immunosuppressive metabolite of leflunomide, A77 1726: inhibition of dihydroorotate dehydrogenase (DHO-DHase), an enzyme involved in the biosynthesis of pyrimidine nucleotides (PyN); and inhibition of protein tyrosine kinases. The in vitro potency of A77 1726 as a DHO-DHase inhibitor is reported to be 10- to 500-fold greater than as a tyrosine kinase inhibitor. These observations suggested that the immunosuppressive efficacy of leflunomide in vivo is related to inhibition of DHO-DHase. However, observations that patients with disorders in the PyN synthetic pathway are not overtly immunodeficient militate against this hypothesis. We investigated the effects of leflunomide in vivo and report that amelioration of lymphoproliferative and autoimmune diseases in MRL/MpJ-lpr/lpr (lpr/lpr) mice by leflunomide is not accompanied by reduced PyN concentrations in lymph node cells. Our hypothesis that lymphocytes could salvage serum uridine to counter the effects of reduced PyN synthesis in vivo was supported by in vitro studies. Finally, we observed that amelioration of disease correlated with a reduction of tyrosine phosphorylated proteins in lymph node cells of lpr/lpr mice. These observations suggest that the primary mechanism by which leflunomide prevents autoimmune and lymphoproliferative diseases in lpr/lpr mice is not depletion of PyN, but correlates with reduced tyrosine phosphorylation concentrations in lymph node cells.
Antigen specificity of dual reactive T hybridomas determines the requirement for CD40 ligand-CD40 interactions.
Authors: Ozaki M E , Karlsson L , Peterson P A , Webb S R 
Published: December 2022

Abstract
CD40 ligand (CD40L) expression on T cells is known to play a crucial role in B cell responses. Some evidence also supports a role for CD40L-CD40 interactions in T cell responses, at least in vivo. Whether the T cell requirement for these interactions is an invariable finding, however, is less clear. Here, we provide evidence that the Ag specificity of T cells influences the requirement for CD40L. T cell hybridomas with dual reactivity for two different Ags, allo-H2-Ap and Mls(a) superantigens, display a differential requirement for CD40L expression. Whereas the response to splenic APC expressing Mls(a) Ags requires CD40L expression, the response to alloantigen-bearing APC does not. The requirement for CD40L expression for the Mls(a) response appears to reflect a strong dependence of this response on ICAM-1 (intercellular adhesion molecule-1) and the ability of CD40-mediated signals to regulate ICAM-1 expression. These findings demonstrate that CD40L-CD40-mediated cross-talk is important for some but not all T cell responses and is influenced by both the type of Ag recognized and the type of APC.
Production of IL-18 (IFN-gamma-inducing factor) messenger RNA and functional protein by murine keratinocytes.
Authors: Stoll S , Müller G , Kurimoto M , Saloga J , Tanimoto T , Yamauchi H , Okamura H , Knop J , Enk A H 
Published: December 2022

Abstract
Recently, the novel cytokine IL-18 (IFN-gamma-inducing factor) has been described as a growth and differentiation factor for Th1 cells. Epidermal keratinocytes (KC) are known to direct T cell education by production of cytokines. Therefore, expression of IL-18 was sought in KC. Epidermal RNA was analyzed following stimulation with contact sensitizers or controls for IL-18 mRNA expression by semiquantitative reverse transcription-PCR. Constitutive expression of IL-18 mRNA was low in untreated epidermal cells (EC), but early up-regulation of IL-18 mRNA signals was detected following application of a contact allergen in vivo. The peak strength of IL-18 signals was observed within 4 to 6 h following stimulation with an allergen. Application of an irritant (benzalconiumchloride) or solvents did not result in increased signal strength. To determine the cellular origin of IL-18 mRNA in EC, depletion experiments were performed. IL-18 signals were not affected by depletion with anti-CD3 (T cells) or anti-MHC class II mAb-coupled beads identifying KC as a major source of IL-18. These results were confirmed by analysis of mRNA derived from the KC cell line PAM 212. Strong IL-18 signals could be detected by reverse transcription-PCR. To delineate whether IL-18 protein was produced by EC/KC, a sandwich ELISA was used to assay for IL-18 production. Supernatants from allergen-stimulated EC and KC showed production of IL-18 protein. To confirm that IL-18 protein was functional, EC or KC supernatants were tested for their ability to induce IFN-gamma production. Significant amounts of IFN-gamma were detected in supernatants of allergen-treated cells. In aggregate, our data indicate that murine KC are a source of both IL-18 mRNA and functional protein.
NKR-P1A stimulation of arachidonate-generating enzymes in rat NK cells is associated with granule release and cytotoxic activity.
Authors: Grazia Cifone M , Roncaioli P , Cironi L , Festuccia C , Meccia A , D'Aló S , Botti D , Santoni A 
Published: December 2022

Abstract
NKR-P1A protein has been implicated in the triggering of NK-mediated natural killing contributing to target cell recognition by NK cells. The aim of the present work was to assess whether NKR-P1A receptor triggering also induced arachidonic acid (AA) generation and to determine the possible role of this event on granule release and cytotoxicity. We demonstrated that activation of fresh peripheral blood rat NK cells by cross-linking with the anti-NKR-P1A 3.2.3 mAb induced calcium-dependent AA release, which is due to the activation of cytosolic phospholipase A2 (cPLA2), secretory phospholipase A2 (sPLA2), and diacylglycerol/monoacylglycerol lipase. We also documented the presence of a type II sPLA2 activity in the supernatant fluids from NKR-P1A-activated rat NK cells, suggesting that AA and lysophospholipids could be mobilized from the outside of the cell. The involvement of AA-generating enzymes in NKR-P1A-induced cytotoxic functions was also investigated. Treatment of effector cells with arachidonyl trifluoromethylketone, a cPLA2 inhibitor; p-bromophenacylbromide, a sPLA2 inhibitor; or RHC80267, a diacylglycerol lipase inhibitor, led to a partial inhibition of the redirected lysis against P815 target cells as well the granule content release induced by NKR-P1A cross-linking. A complete abolishment of these events was observed when the cells were simultaneously incubated with all three inhibitors. Taken together, our results support a crucial role for the arachidonate-generating enzymes in the induction of lytic activity of NK cells directly or by leading to generation of additional mediators that can play a role in the context of NK cell activation and cytotoxic functions.
IL-12 treatment attenuates T helper cell type 2 and B cell responses but does not improve vaccine-enhanced lung illness.
Authors: Hussell T , Khan U , Openshaw P 
Published: December 2022

Abstract
In humans and mice, sensitization to respiratory syncytial virus (RSV) Ags can result in severe inflammatory lung disease during subsequent infection with RSV. Although specific antiviral T cells are thought to be responsible for this augmentation of disease, the precise roles of different functional subsets are unknown, and no protective nonpathogenic subset has been defined. BALB/c mice sensitized to the major surface glycoprotein of RSV (G) expressed by recombinant vaccinia virus develop Th2-driven lung eosinophilia after intranasal challenge with RSV. In an attempt to manipulate the outcome of vaccination, we treated mice with IL-12 at various times during vaccination and challenge. IL-12 treatment reduced the vaccine-induced lung eosinophilia during RSV challenge, but increased the total lymphoid cell infiltration into the alveolar space. Analysis of intracellular cytokines by flow cytometry showed that IFN-gamma production during challenge was increased, and IL-4 and IL-5 levels were reduced by IL-12 treatment. In control treated mice, 40 to 50% of the lung lymphoid cells were B cells. Treatment with IL-12 reduced this figure to approximately 1.5%. Although IL-12 treatment reduced lung eosinophilia, illness (as assessed by weight loss) was not eliminated and, in some experiments, was increased. The present study shows that reversing Th2-associated pathology with IL-12 does not necessarily benefit the host.
Differential expression of transcription directed by a discrete NF-AT binding element from the IL-4 promoter in naive and effector CD4 T cells.
Authors: Aune T M , Flavell R A 
Published: December 2022

Abstract
Acquiring the ability to selectively produce IFN-gamma or IL-4 is a fundamental property of the immune system and enables T cell subsets (Th1, Th2) to deliver their effector functions. To create an experimental system to examine regulation of critical promoter elements within the IL-4 gene, we have prepared and analyzed transgenic mice expressing the luciferase gene under the control of the distal NF-AT binding site from the IL-4 promoter. This site is immediately adjacent to an AP-1 site, and this NF-AT/AP-1 composite site is termed either P1 or PubB. The distal NF-AT site we have used to prepare these reporter transgenic mice lacks the AP-1 binding site but contains the NF-AT binding site (P1(NF-AT)) These transgenic mice were also intercrossed with transgenic mice expressing a single MHC class II-restricted TCR. Expression of transcriptional activity under the control of P1(NF-AT) was observed only in effector T cells, and not naive T cells, after stimulation with Ag or polyclonal stimuli. By contrast, gel mobility shift assays showed that nuclear extracts from both naive and effector T cells contained NF-AT, which could effectively bind to the P1(NF-AT) element. IL-4-stimulated Th2 differentiation did not increase the TCR responsiveness of the P1(NF-AT) element by more than 2-fold but increased production of IL-4 protein by more than 10-fold. These data suggest that factors interacting with the P1(NF-AT) element regulate transcriptional activity in a naive/effector T cell-specific manner but not in a Th1/Th2-specific manner. Th1/Th2-specific regulation of the composite P1 element may result from regulation of transacting factors that bind to the AP-1 portion of this element.
Effect of the inducible nitric oxide synthase inhibitors aminoguanidine and L-N6-(1-iminoethyl)lysine on zymosan-induced plasma extravasation in rat skin.
Authors: Ridger V C , Pettipher E R , Bryant C E , Brain S D 
Published: December 2022

Abstract
The effect of nitric oxide synthase (NOS) inhibitors on plasma extravasation in a rat model of zymosan-induced inflammation has been investigated. Plasma extravasation was determined in response to intradermal test agents over 0 to 45 min or 0 to 4 h by the accumulation of i.v. injected 125I-labeled human serum albumin. Zymosan (1-100 microg/site) produced a dose- and time-dependent plasma extravasation. N(G)-nitro-L-arginine methyl ester (30-300 nmol/site), but not aminoguanidine (AG; 10-300 nmol/site) or L-N6-(1-iminoethyl)lysine (L-NIL; 10-300 nmol/site), significantly (p &lt; 0.01) inhibited zymosan-induced (10 microg/site) plasma extravasation over 0 to 45 min. However, both AG and L-NIL produced significant (p &lt; 0.05) inhibition over 0 to 4 h. The inhibition produced by AG was reversed by i.v. L-arginine or by coinjection of the vasodilator, calcitonin gene-related peptide. Zymosan (10-100 microg/site) induced an increase in dermal blood flow (laser-Doppler flowmetry) and this was inhibited by AG. Neutrophils were depleted selectively with antiserum, but this did not affect plasma extravasation except at the highest dose of zymosan (100 microg/site). Furthermore, zymosan-induced edema was not modified at either time point by pretreatment with the cyclooxygenase inhibitor indomethacin (30 micromol/kg, s.c., -30 min). In conclusion, in this model of dermal inflammation, it is suggested that inducible NOS inhibitors selectively remove an inducible NOS component that, at least in part, acts to increase microvascular blood flow and thus the edema formation observed during 0 to 4 h. There is no evidence of a contributory role for neutrophils or cyclooxygenase products in this model.
Transgenic monocyte chemoattractant protein-1 (MCP-1) in pancreatic islets produces monocyte-rich insulitis without diabetes: abrogation by a second transgene expressing systemic MCP-1.
Authors: Grewal I S , Rutledge B J , Fiorillo J A , Gu L , Gladue R P , Flavell R A , Rollins B J 
Published: December 2022

Abstract
Monocyte chemoattractant protein-1 (MCP-1) is a CC chemokine that attracts monocytes and T lymphocytes in vitro; however, its in vivo functions are poorly understood. To address this question, we constructed transgenic mice expressing MCP-1 controlled by an insulin promoter. These mice developed a chronic insulitic infiltrate composed of F4/80+ monocytes with minor populations of CD4+, CD8+, and B220+ cells. Despite persistent transgene expression, the insulitis never progressed, and blood glucose levels remained normal. Thus, MCP-1 alone is sufficient to elicit a monocytic infiltrate, but not to activate elicited cells. These results differ from those obtained with another transgenic model using the mouse mammary tumor virus long terminal repeat, in which mice expressed substantial MCP-1 in several organs but had no infiltrates. However, mice expressing both transgenes had minimal insulitis, indicating that high systemic levels of MCP-1 prevented monocytes from responding to local MCP-1. Thus, the ability of MCP-1 to elicit monocytic infiltration depends on its being expressed at low levels in an anatomically restricted area.
Differential regulation of indoleamine 2,3-dioxygenase expression by nitric oxide and inflammatory mediators in IFN-gamma-activated murine macrophages and microglial cells.
Authors: Alberati-Giani D , Malherbe P , Ricciardi-Castagnoli P , Köhler C , Denis-Donini S , Cesura A M 
Published: December 2022

Abstract
Induction of indoleamine 2,3-dioxygenase (IDO) and nitric oxide synthase (NOS) is involved in the immunomodulatory roles of IFN-gamma and evidence suggests that these pathways are functionally cross-regulated. We report here that nitric oxide (NO) negatively modulates the expression of IDO activity in IFN-gamma-primed macrophages, but not in microglial cells from mouse. In MT2 macrophages, the induction of IDO activity by IFN-gamma was further increased by the presence of NOS inhibitors, whereas culturing of IFN-gamma-activated MT2 cells with NO generators produced a marked reduction of IDO activity expression. Conversely, neither NOS inhibitors nor exogenous NO affected the induction of the enzyme activity in N11 microglial cells after IFN-gamma activation. LPS and picolinic acid, two costimulatory agents that up-regulate inducible NOS in activated cells, regulated IDO induction differently in the two cell lines. LPS and picolinic acid caused a significant decrease of IDO activity in IFN-gamma-activated MT2 cells. This effect, however, did not appear to be mediated by the ability of LPS and picolinic acid to stimulate NO production. In N11 cells, LPS further stimulated the enzyme activity and picolinic acid had no effect. Northern blot analysis revealed that, in MT2 macrophages, NOS inhibitors increased the levels of IDO mRNA, while a reduction was observed with picolinic acid. No changes in IDO mRNA levels were detected in N11 cells. Consistent with the functional heterogeneity of phagocytes, the reported results indicate the existence of marked differences in the regulation of IDO expression between murine macrophages and microglial cells.
Role of macrophages and macrophage-derived cytokines in the pathogenesis of Kilham rat virus-induced autoimmune diabetes in diabetes-resistant BioBreeding rats.
Authors: Chung Y H , Jun H S , Kang Y , Hirasawa K , Lee B R , Van Rooijen N , Yoon J W 
Published: December 2022

Abstract
The diabetes-resistant BioBreeding (DR-BB) rat, derived from diabetes-prone forebears, does not normally develop spontaneous insulitis or diabetes, but when infected with Kilham rat virus (KRV) this animal develops autoimmune diabetes similar to the diabetes-prone BioBreeding (DP-BB) rat. In this study, we attempted to determine whether macrophages and macrophage-derived cytokines play a role in the development of KRV-induced diabetes in DR-BB rats. Seventy-eight percent of DR-BB rats treated with KRV and poly(I:C) develop diabetes, whereas depletion of macrophages with liposome-encapsulated dichloromethylene diphosphonate (lip-Cl2MDP) in KRV and poly(I:C)-treated DR-BB rats results in the near-complete prevention of insulitis and diabetes. Measurement of the macrophage-derived cytokines IL-12, TNF-alpha, and IL-1beta revealed a selective increase of their expression, after KRV infection, in the splenic lymphocytes and the pancreatic islets. Measurement of CD4+ T cell-derived cytokines revealed that IL-2 and IFN-gamma cytokine gene expression closely correlates with an elevation of IL-12, but IL-4 and IL-10 do not change. Depletion of macrophages before the isolation of splenic lymphocytes from DR-BB rats treated with KRV and poly(I:C) resulted in the loss of ability to transfer diabetes to young DP-BB rats. On the basis of these observations, we conclude that macrophages and macrophage-derived cytokines play a critical role in the cascade of events leading to the destruction of pancreatic beta cells, culminating in the development of insulin-dependent diabetes mellitus.
American Association of Immunologists Presidential Address: doing it together: a perspective on the process of experimental science.
Authors: Knight K L 
Published: December 2022

Abstract
We are witnessing profound changes in how experimental science is done and the rate at which scientists are discovering nature's secrets. While we are experiencing this phenomenal change, we are also at risk, because along with these changes comes the potential for altering the values by which we do science. I share with everyone in our field an abiding concern that scientists of the next generation embrace the values that have guided my generation and the generations of scientists that have preceded me. Because relationships in science are key to passing on these values, I have focused the first part of this address on the importance that relationships have played in guiding my scientific process. In the second part; Looking Toward Our Future, I discuss how the mentoring relationship can serve as an antidote to pressures that threaten our scientific values.
The effect of NK cell activation by tumor cells on antigen-specific antibody responses.
Authors: Koh C Y , Yuan D 
Published: December 2022

Abstract
In addition to mediating direct cytotoxicity, NK cells can exert regulatory effects on specific immune responses. For example, injection of poly (I:C) can alter specific Ab responses, which is attributable to the production of IFN-gamma by NK cells. To test whether direct activation of NK cells can exert the same effect, we have injected, at the same time as Ag challenge, BCL1-C11 tumor cells, which are highly effective inducers of IFN-gamma production by NK cells. The results show a specific enhancement of the IgG2a response, which does not occur with a tumor (70Z/3) that does not induce IFN-gamma production. This enhancement is NK cell and IL-12 dependent. However, BCL1-C11 cells cannot directly induce IL-12 production in peritoneal exudate cells (PECs). On the other hand, PECs from tumor-treated mice produce IL-12 in response to LPS, suggesting that they are primed in vivo. Furthermore, the IL-12 production is NK cell and IFN-gamma dependent. These results indicate that if tumor cells can directly activate NK cells to produce IFN-gamma, this cytokine initiates an amplification loop by activating macrophages to produce IL-12, which in turn activates NK cells further, resulting in the alteration of the isotype distribution of specific Ab responses. Production of the appropriate Ab isotype should enhance Ab-dependent cellular cytotoxicity against targets mediated by NK cells, implicating their role(s) in the specific immune response as well as the initial nonspecific phase.