bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enhanced Interaction of HLA-DM with HLA-DR in Enlarged Vacuoles of Hereditary and Infectious Lysosomal Diseases
Authors: Lem Lawrence , Riethof David A. , Scidmore-Carlson Marci , Griffiths Gillian M. , Hackstadt Ted , Brodsky Frances M. 
Published: December 2022

AbstractFollowing biosynthesis, class II MHC molecules are transported through a lysosome-like compartment, where they acquire antigenic peptides for presentation to T cells at the cell surface. This compartment is characterized by the presence of HLA-DM, which catalyzes the peptide loading process. Here we report that the morphology and function of the class II loading compartment is affected in diseases with a phenotypic change in lysosome morphology. Swollen lysosomes are observed in cells from patients with the hereditary immunodeficiency Chediak-Higashi syndrome and in cells infected with Coxiella burnetii, the rickettsial organism that causes Q fever. In both disease states, we observed that HLA-DR and HLA-DM accumulate in enlarged intracellular compartments, which label with the lysosomal marker LAMP-1. The distribution of class I MHC molecules was not affected, localizing disease effects to the endocytic pathway. Thus, cellular mechanisms controlling lysosome biogenesis also affect formation of the class II loading compartment. Analysis of cell surface class II molecules revealed that their steady-state levels were not reduced on diseased cells. However, in both disease states, enhanced interaction between HLA-DR and HLA-DM was detected. In the Chediak-Higashi syndrome cells, this correlated with more efficient removal of the CLIP peptide. These findings suggest a mechanism for perturbation of Ag presentation by class II molecules and consequent immune deficiencies in both diseases.
Evidence for a Role of IL-17 in Organ Allograft Rejection: IL-17 Promotes the Functional Differentiation of Dendritic Cell Progenitors
Authors: Antonysamy Mary A. , Fanslow William C. , Fu Fumin , Li Wei , Qian Shiguang , Troutt Anthony B. , Thomson Angus W. 
Published: December 2022

AbstractIL-17 is a T cell-derived cytokine that stimulates stromal cells and macrophages to secrete proinflammatory cytokines. We hypothesized that IL-17 might play a role in alloimmune responses, and that interference with its activity might suppress allograft rejection. IL-17R:Fc or control IgG was added at the start of mouse MLR or was administered i.p. (100–500 μg/day) for different durations post-transplant to murine recipients of MHC-mismatched cardiac allografts. IL-17R:Fc (50–200 μg/ml) markedly inhibited T cell proliferation in vitro and significantly prolonged nonvascularized cardiac allograft median survival time from 13 to 20 days (100 μg/day; days 0 and 1) or to 19 days (100–300 μg/day; days 0–4). Survival of vascularized grafts was also extended significantly from 10.5 to 19 days by IL-17R:Fc (500 μg/day; days 0–6). To address a possible mechanism by which IL-17 may promote alloreactivity, we examined the influence of IL-17 on the differentiation and function of bone marrow-derived cells propagated in granulocyte-macrophage CSF with or without IL-4 to promote dendritic cell (DC) growth. A minor proportion of CD11c+ DC expressed the IL-17R. IL-17 promoted the maturation of DC progenitors, as evidenced by increased cell surface expression of CD11c, costimulatory molecules (CD40, CD80, CD86), and MHC class II Ag, and allostimulatory capacity. IL-17 had a lesser effect on the phenotype and function of more fully differentiated myeloid DC. These findings suggest a role for IL-17 in allogeneic T cell proliferation that may be mediated in part via a maturation-inducing effect on DC. IL-17 appears to be a novel target for therapeutic intervention in allograft rejection.
Chemotactic Migration Triggers IL-8 Generation in Neutrophilic Leukocytes
Authors: Siddiqui Rafat A. , Akard Luke P. , Garcia J. G. N. , Cui Yi , English Denis 
Published: December 2022

AbstractNeutrophils recovered from inflammatory exudates possess increased levels of IL-8, but exposure of neutrophils to chemoattractants results in only a modest stimulation of IL-8 generation. This study was undertaken to explore the hypothesis that IL-8 generation in these cells is dependent upon the process of migration. Neutrophils synthesized up to 30 times as much IL-8 during migration in response to a gradient of diverse chemoattractants than they did when stimulated directly by the attractants in the absence of a gradient. This IL-8 response was dependent on migration since it was not observed in cells exposed to concentration gradients of chemoattractants under conditions that prevented cell movement. While actinomycin-D (1 μg/ml) had little influence on the generation of IL-8 during chemotaxis, the protein synthesis inhibitor cycloheximide (10 μg/ml) markedly blunted the accumulation of cell-associated IL-8, suggesting that new protein synthesis from preexisting mRNA was responsible for the effect. Consistent with this interpretation, migrating cells incorporated over 10 times as much [3H]leucine into IL-8 as did nonmotile neutrophils exposed to chemoattractants. A substantial portion of the IL-8 generated during chemotaxis was released upon subsequent metabolic stimulation. Thus, the IL-8 synthesized during chemotaxis is uniquely positioned to exert a regulatory influence on inflammatory processes governed by neutrophilic leukocytes responding to inflammatory and infectious stimuli.
Adhesion-Dependent Degranulation of Neutrophils Requires the Src Family Kinases Fgr and Hck
Authors: Mócsai Attila , Ligeti Erzsébet , Lowell Clifford A. , Berton Giorgio 
Published: December 2022

Abstract
Polymorphonuclear neutrophils (PMN) adherent to integrin ligands respond to inflammatory mediators by reorganizing their cytoskeleton and releasing reactive oxygen intermediates. As Src family tyrosine kinases are implicated in these responses, we investigated their possible role in regulating degranulation. Human PMN incubated on fibrinogen released lactoferrin in response to TNF-α and this response was inhibited by PP1, a Src family tyrosine kinase inhibitor. This drug had no effect on lactoferrin secretion induced by PMA, an adhesion-independent agonist of PMN degranulation. However, PP1 blocked secretion in PMN plated on plain tissue culture plastic, a surface inducing PMN spreading in the absence of any stimulus. Double knockout hck−/−fgr−/− PMN adherent to collagen or fibrinogen failed to release lactoferrin in response to TNF-α but responded to PMA as wild-type PMN. Degranulation induced by spreading over tissue culture plastic was also defective in hck−/−fgr−/− PMN. Defective adhesion-dependent degranulation required the absence of both kinases, because single knockout fgr−/− or hck−/− PMN responded as wild-type cells. Analysis of lactoferrin secretion in hck−/−fgr−/− or PP1-treated, suspended PMN showed that Src kinases are not implicated in degranulation dependent on activation of protein kinase C or increase in intracellular free Ca2+ but may play a role in the response to FMLP of cytochalasin B-treated PMN. These findings identify a role for Src family kinases in a signaling pathway leading to granule-plasma membrane fusion and suggest that Fgr and Hck would be targets for pharmacological control of adhesion-dependent degranulation in the inflammatory site.
Involvement of MIIC-Like Late Endosomes in B Cell Receptor-Mediated Antigen Processing in Murine B Cells
Authors: Drake James R. , Lewis Timothy A. , Condon Krista B. , Mitchell Richard N. , Webster Paul 
Published: December 2022

Abstract
Currently, the involvement of classical vs novel endocytic compartments in the phenomenon of B cell receptor (BCR)-mediated Ag processing is a matter of considerable debate. In murine B cells, class II vesicles (CIIV) represent a novel endocytic compartment involved in BCR-mediated Ag processing and class II peptide loading. Alternatively, in human B cells, the MHC class II-enriched compartment (MIIC) represents a lysosome (L)-like endocytic compartment that appears to be involved in this process. Presently, the relationship between CIIV, MIIC, and classical endosomes and L remains to be determined. Using density gradient centrifugation, a subcellular compartment morphologically and immunologically similar to human MIIC has been identified, isolated, and characterized in murine B cells. These MIIC-like vesicles represent a population of class II-positive late endosomes (LE) and are distinct from CIIV. MIIC-like LE are uniquely marked by the thiol protease cathepsin B, and along with mature L, appear to be the major repository of DM molecules in these cells. Importantly, both MIIC-like LE and CIIV isolated from Ag-pulsed B cells contain BCR-internalized Ag as well as antigenic peptide-class II complexes.
T Cell Activation Signals Up-Regulate p38 Mitogen-Activated Protein Kinase Activity and Induce TNF-α Production in a Manner Distinct from LPS Activation of Monocytes
Authors: Schafer Peter H. , Wang Liwen , Wadsworth Scott A. , Davis Janet E. , Siekierka John J. 
Published: December 2022

Abstractp38 mitogen-activated protein kinase (MAPK) (p38) is involved in various cellular responses, including LPS stimulation of monocytes, resulting in production of proinflammatory cytokines such as TNF-α. However, the function of p38 during antigenic stimulation of T cells is largely unknown. Stimulation of the human Th cell clone HA-1.70 with either the superantigen staphylococcal enterotoxin B (SEB) or with a specific antigenic peptide resulted in p38 activation and the release of TNF-α. MAPK-activated protein kinase-2 (MAPKAPK-2), an in vivo substrate for p38, was also activated by T cell signaling. SB 203580, a selective inhibitor of p38, blocked p38 and MAPKAPK-2 activation in the T cell clone but did not completely inhibit TNF-α release. PD 098059, a selective inhibitor of MAPK kinase 1 (MEK1), blocked activation of extracellular signal-regulated kinase (ERK) and partially blocked TNF-α production by the clone. In human peripheral T cells, p38 was not activated by SEB, but rather by CD28 cross-linking, whereas in the human leukemic T cell line Jurkat, p38 was activated by CD3 and CD28 cross-linking in an additive fashion. TNF-α production by peripheral T cells in response to SEB and anti-CD28 mAb correlated more closely with ERK activity than with p38 activity. Therefore, various forms of T cell stimulation can activate the p38 pathway depending on the cells examined. Furthermore, unlike LPS-stimulated monocytes, TNF-α production by T cells is only partially p38-dependent.
Inhibition of Th1 Polarization by Soluble TNF Receptor Is Dependent on Antigen-Presenting Cell-Derived IL-12
Authors: Becher Burkhard , Blain Manon , Giacomini Paul S. , Antel Jack P. 
Published: December 2022

AbstractTh1-polarized CD4+ T cells are considered central to the development of a number of target-directed autoimmune disorders including multiple sclerosis. The APC-derived cytokine IL-12 is a potent inducer of Th1 polarization in T cells. Inhibition of IL-12 in vivo blocks the development of experimental allergic encephalomyelitis, the animal model for multiple sclerosis. Based on previous work that suggests that the production of IL-12 by activated human central nervous system-derived microglia is regulated by autocrine TNF-α, we wanted to determine whether inhibition of TNF could induce a reduction of Th1 responses by its impact on systemic APCs. We found that soluble TNFR p75-IgG fusion protein (TNFR:Fc) inhibited production of IFN-γ by allo-Ag-activated blood-derived human CD4 T cells. We documented reduced IL-12 p70 production by APCs in the MLR. By adding back recombinant IL-12, we could rescue IFN-γ production, indicating that TNFR:Fc acts on APC-derived IL-12. Consistent with an inhibition of the Th1 polarization, we found a decreased expression of IL-12R-β2 subunit on the T cells. Furthermore, the capacity of T cells to secrete IFN-γ upon restimulation when previously treated with TNFR:Fc is impaired, whereas IL-2 secretion was not altered. Our results define a TNF-dependent cytokine network that favors development of Th1 immune responses.
Presence of Pentoxifylline During T Cell Priming Increases Clonal Frequencies in Secondary Proliferative Responses and Inhibits Apoptosis
Authors: Gupta Manisha , George Anna , Sen Ranjan , Rath Satyajit , Durdik Jeannine M. , Bal Vineeta 
Published: December 2022

AbstractNaive T cells appear to be primed by specific Ag to differentiate into either effectors or memory cells. We have been analyzing the factors involved in this differential commitment in the priming of alloresponsive human T cells in vitro and have shown that the presence of a phosphodiesterase inhibitor, pentoxifylline (POX), during priming results in a decrease in the primary response and enhancement in the secondary proliferative response. We now show that the POX-mediated effect can be mimicked by dibutyryl cAMP. The secondary response enhancement is due to the effects of POX on the T cells rather than the APCs, because even fixed APCs can prime T cells in the presence of POX. POX affects T cells directly by increasing clonal frequency rather than the burst size of the secondary responders. The known inhibition of IL-2 production by POX is not responsible for this effect, because exogenous IL-2 supplementation does not block it. The presence of POX during priming alters the outcome of T cell activation, resulting in a lower frequency of cells expressing IL-2Rα (CD25) and a decrease in their subsequent apoptosis, and this anti-apoptotic effect is consistent with the enhanced commitment of T cells to secondary responsiveness by POX.
Antigen Recognition Influences Transendothelial Migration of CD4+ T Cells
Authors: Marelli-Berg Federica M. , Frasca Loredana , Weng Ling , Lombardi Giovanna , Lechler Robert I. 
Published: December 2022

Abstract
The functional significance of MHC class II expression by vascular endothelial cells remains obscure. In this study the possibility that Ag presentation by endothelial cells (EC) influences T cell transmigration, facilitating the recruitment of Ag-specific T cells into tissues, was investigated. The frequencies of T cells with specificity for an HLA-DR alloantigen, or for the recall Ag tetanus toxoid (TT), were measured in peripheral blood CD45RO+ (memory) CD4+ T cells before and after transmigration through γ-IFN-treated EC monolayers. Frequencies of anti-DR17, IL-2-secreting T cells were fourfold higher in the T cells that transmigrated through a monolayer of DR17-expressing EC. Similar increases were seen in TT-specific, DR7-restricted T cells that transmigrated through TT-pulsed, DR7-expressing EC. To examine more directly the effects of cognate recognition of Ag presented by EC, T cell clones were used. For clones that proliferated in a costimulation-independent manner to Ag presented by EC, cognate recognition arrested transmigration. In contrast, Ag presentation by EC to B7-dependent T cell clones, which do not proliferate following cognate recognition of EC, enhanced the rate of transendothelial migration. These data suggest that Ag presentation by EC may serve to augment the recruitment of Ag-specific T cells into tissues and that proliferation and transmigration are mutually exclusive T cell responses.
IFN-γ Down-Regulates MHC Expression and Antigen Processing in a Human B Cell Line
Authors: O’Neil Deborah , Swanton Charles , Jones Andrew , Medd Patrick G. , Rayment Neil , Chain Benjamin 
Published: December 2022

Abstract
IFN-γ is a crucial mediator in the induction of cell-mediated Th1-type responses but is predominantly a negative regulator of B cell differentiation and proliferation. This cytokine is therefore a key factor in determining Th1 vs Th2 differentiation. This study investigates the action of IFN-γ in modulation of HLA-DR expression and Ag presentation by EBV-transformed human B cell lines. In contrast to its action on the monocyte/macrophage, IFN-γ down-regulates surface MHC expression on these B cells, and this regulation is posttranscriptional. In parallel with MHC down-regulation, there is a reduced capability to process and present exogenous protein and peptide Ag to T cell hybridomas. IFN-γ does not change the rates of fluid phase endocytosis or exocytosis in this model system but correlates with an up-regulation of the lysosomal enzymes cathepsins B and D.
Galectin-1 Specifically Modulates TCR Signals to Enhance TCR Apoptosis but Inhibit IL-2 Production and Proliferation
Authors: Vespa Glaucia N. R. , Lewis Linda A. , Kozak Katherine R. , Moran Miriana , Nguyen Julie T. , Baum Linda G. , Miceli M. Carrie 
Published: December 2022

AbstractGalectin-1 is an endogenous lectin expressed by thymic and lymph node stromal cells at sites of Ag presentation and T cell death during normal development. It is known to have immunomodulatory activity in vivo and can induce apoptosis in thymocytes and activated T cells (1–3). Here we demonstrate that galectin-1 stimulation cooperates with TCR engagement to induce apoptosis, but antagonizes TCR-induced IL-2 production and proliferation in a murine T cell hybridoma and freshly isolated mouse thymocytes, respectively. Although CD4+CD8+ double positive cells are the primary thymic subpopulation susceptible to galectin-1 treatment alone, concomitant CD3 engagement and galectin-1 stimulation broaden susceptible thymocyte subpopulations to include a subset of each CD4−CD8−, CD4+CD8+, CD4−CD8+, and CD4+CD8− subpopulations. Furthermore, CD3 engagement cooperates with suboptimal galectin-1 stimulation to enhance cell death in the CD4+CD8+ subpopulation. Galectin-1 stimulation is shown to synergize with TCR engagement to dramatically and specifically enhance extracellular signal-regulated kinase-2 (ERK-2) activation, though it does not uniformly enhance TCR-induced tyrosine phosphorylation. Unlike TCR-induced IL-2 production, TCR/galectin-1-induced apoptosis is not modulated by the expression of kinase inactive or constitutively activated Lck. These data support a role for galectin-1 as a potent modulator of TCR signals and functions and indicate that individual TCR-induced signals can be independently modulated to specifically affect distinct TCR functions.
Deficiency of IL-5 Receptor α-Chain Selectively Influences the Development of the Common Mucosal Immune System Independent IgA-Producing B-1 Cell in Mucosa-Associated Tissues
Authors: Hiroi Takachika , Yanagita Manabu , Iijima Hideki , Iwatani Kouichi , Yoshida Toshimi , Takatsu Kiyoshi , Kiyono Hiroshi 
Published: December 2022

Abstract
Deletion of IL-5Rα-chain (IL-5Rα−/−) selectively influenced the mucosal IgA responses in vivo. While levels of IgA in mucosal secretions were more reduced in IL-5Rα−/− mice than in wild-type mice, the levels of IgA in serum were not changed. The frequency of IgA-producing cells was reduced in mucosal effector sites (e.g., intestinal lamina propria and nasal passage), but not in inductive sites such as Payer’s patches and nasal-associated lymphoreticular tissues in IL-5Rα−/− mice. IgA-committed (surface IgA+; sIgA+) B-1 cells mainly resided in mucosal effector tissues, while conventional sIgA+ B (B-2) cells formed in mucosal inductive sites of wild-type mice. In contrast, in the effector tissue of IL-5Rα−/− mice, sIgA+ B-1 cells, but not sIgA+ B-2 cells in the inductive site, were significantly reduced. IL-5Rα was more expressed on sIgA+ B-1 cells than was IL-6R, while both IL-5Rα and IL-6R were expressed on sIgA+ B-2 cells in wild-type mice. sIgA+ B-1 cells produced high levels of IgA with rIL-5 rather than of rIL-6 in vitro. Taken together, the findings suggest that the IL-5/IL-5R signaling pathway is critically important for the development of common mucosal immune system independent sIgA+ B-1 cell in mucosal effector tissues in vivo.
T Cell Priming Enhances IL-4 Gene Expression by Increasing Nuclear Factor of Activated T Cells
Authors: Cron Randy Q. , Bort Susan J. , Wang Yunxia , Brunvand Mark W. , Lewis David B. 
Published: December 2022

AbstractThe repetitive activation of T cells (priming) enhances the expression of many cytokines, such as IL-4, but not others, such as IL-2. Molecular mechanisms underlying selective expression of cytokines by T cells remain poorly understood. Here we show that priming of CD4 T cells selectively enhances IL-4 expression relative to IL-2 expression by a transcriptional mechanism involving nuclear factor of activated T cells (NFAT) proteins. As detected by in vivo footprinting, priming markedly increases the activation-dependent engagement of the P0 and P1 NFAT-binding elements of the IL-4 promoter. Moreover, each proximal P element is essential for optimal IL-4 promoter activity. Activated primed CD4 T cells contain more NFAT1 and support greater NFAT-directed transcription than unprimed CD4 T cells, while activator protein 1 binding and activator protein 1-mediated transcription by both cell types is similar. Increased expression of wild-type NFAT1 substantially increases IL-4 promoter activity in unprimed CD4 T cells, suggesting NFAT1 may be limiting for IL-4 gene expression in this cell type. Furthermore, a truncated form of NFAT1 acts as a dominant-negative, reducing IL-4 promoter activity in primed CD4 T cells and confirming the importance of endogenous NFAT to increased IL-4 gene expression by effector T cells. NFAT1 appears to be the major NFAT family member responsible for the initial increased expression of IL-4 by primed CD4 T cells.
Alternative Splicing and Hypermutation of a Nonproductively Rearranged TCR α-Chain in a T Cell Hybridoma
Authors: Marshall Brendan , Schulz Ruth , Zhou Min , Mellor Andrew 
Published: December 2022

Abstract
Like Ig genes, TCR genes are formed by somatic rearrangements of noncontiguous genomic V, J, and C regions. Unlike Ig genes, somatic hypermutation of TCR V regions is an infrequent event. We describe the occurrence of spontaneous hypermutation in a nonproductively rearranged TCR α-chain gene in a clonal T cell hybridoma that had lost its productively rearranged α-chain. The mutating hybridoma was eventually supplanted in culture by a nonmutating variant that had restored an open reading frame in the nonproductively rearranged TCR α-chain through the use of cryptic splice sites in the Vα region. Evidence is presented for the presence of cDNA reverse transcripts of the TCR α-chain within the hybridoma, suggesting a role for reverse transcriptase in the generation of mutations.
The Extracellular Domain of the ζ-Chain Is Essential for TCR Function
Authors: Johansson Britt , Palmer Ed , Bolliger Luca 
Published: December 2022

AbstractThe ζ-chain homodimer is a key component in the TCR complex and exerts its function through its cytoplasmic immunoreceptor-tyrosine activation motif (1). The ζ-chain extracellular (EC) domain is highly conserved; however, its functional and structural contributions to the TCR signaling have not been elucidated. We show that the EC domain of the ζ homodimer is essential for TCR surface expression. To gain a more detailed structural and functional information about the ζ-chain EC domain, we applied a cysteine scanning mutagenesis to conserved amino acids of the short domain. The results showed that the interchain disulfide bridge can be displaced by seven or eight amino acids along the EC domain. The TCR signaling efficacy was dramatically reduced during peptide/MHC engagement in the ζ mutants containing the displaced disulfide bond. These signaling defective ζ mutants produced an unconventional early tyrosine phosphorylation pattern. While the tyrosine phosphorylated forms of ζ (p21 and p23) could be observed during Ag stimulation, downstream signaling events such as the generation of phospho-p36, higher m.w. forms of phospho-ζ, and phospho-ζ/ZAP-70 complexes were impaired. Together these results suggest an important function of the phylogenetically conserved ζ-EC domain.