bluuebunny/crossref_metadata_2025_split huggingface dataset:
CD11b/CD18 (Mac-1) is required for degranulation of human eosinophils induced by human recombinant granulocyte-macrophage colony-stimulating factor and platelet-activating factor.
Authors: Horie S , Kita H 
Published: December 2022

Abstract
Recent evidence suggests adhesion molecules play an important role in the function of leukocytes. Because human eosinophils are known to express beta 2 integrins, we hypothesized that these adhesion molecules mediate the effector function of eosinophils. Normal human eosinophils incubated in albumin-coated polystyrene plates released granule protein and produced superoxide anion when stimulated with human recombinant granulocyte-macrophage CSF (rGM-CSF), platelet-activating factor (PAF), or PMA. Simultaneous monitoring of eosinophil adhesion and degranulation showed that degranulation was always preceded by cellular adhesion regardless of stimuli. Furthermore, eosinophil degranulation induced by human rGM-CSF and PAF was abolished in suspension culture of the cells when the cell suspensions were gently stirred. To identify the molecules involved in this adhesion-dependent degranulation, we have investigated the effects of mAbs (mAb) against beta 2 integrins. mAb reactive with CD18 markedly inhibited the eosinophil adhesion and degranulation induced by PAF and human rGM-CSF. mAb reactive with CD11b also moderately inhibited the adhesion and degranulation. In contrast, mAb reactive with CD11a slightly enhanced or showed no effect on the adhesion and degranulation by human rGM-CSF or PAF. Superoxide production induced by human rGM-CSF and PAF was also abolished by the treatment of cells with anti-CD18 mAb. mAb against CD11b and CD18 had little effect on degranulation and superoxide production induced by PMA. These results indicate that CD11b/CD18 (Mac-1)-dependent cellular adhesion plays an important role in the degranulation and superoxide production of eosinophils induced by human rGM-CSF and PAF, and that these mechanisms may be employed in vivo where eosinophils contact with stromal cells and/or proteins.
Antigenic surface of the bee venom allergen phospholipase A2. Structural functional analysis of human IgG4 antibodies reveals potential role in protection.
Authors: Dudler T , Schneider T , Annand R R , Gelb M H , Suter M 
Published: December 2022

Abstract
In the human immune response to the main bee venom allergen phospholipase A2 (PLA2), Abs of the IgG4 isotype are associated with protection. The antigenic sites of PLA2 that are recognized by two mAb of this isotype have been analyzed at the molecular level. The interaction of PLA2 with these two Abs has previously been shown to depend on the conformation of the Ag and to be sensitive to lysine modifications. Therefore, genetically engineered Ag displaying single point mutations of lysine residues were generated. Nine out of twelve surface-exposed lysine residues were substituted by glutamate or glutamine, and the effect of individual mutations on mAb binding was analyzed in the context of the folded Ag. Substitution of lysine at position 25 with either glutamate or glutamine completely abrogates binding to both mAb. All other mutants do not show a difference in binding when compared with wild-type Ag. Probing of sera from bee keepers with lysine 25 mutants reveals that a significant proportion of serum Abs of the IgG4 isotype display specificity for this epitope, suggesting that this represents a major B cell-antigenic site in hyperimmune individuals. We further found that both mAbs inhibit the catalytic activity of PLA2, a property that may account for the protective role of IgG4 Abs in hyperimmune individuals.
LFA-1-mediated antigen-independent T cell adhesion is regulated by CD4 and p56lck tyrosine kinase.
Authors: Mazerolles F , Barbat C , Meloche S , Gratton S , Soula M , Fagard R , Fischer S , Hivroz C , Bernier J , Sekaly R P 
Published: December 2022

Abstract
We examined the role of CD4 and p56lck in the regulation of LFA-1-dependent T cell adhesion to B cells and to fibroblasts expressing ICAM-1 and HLA-DR by using various transfectant constructions. Although CD4 transfection in CD4low HUT78 T cell lines did not significantly modify their maximal binding to B cells and fibroblasts, it made the LFA-1-dependent adhesion sensitive to inhibition by anti-CD4 Ab, HIV-1 (env) gp 160, and a 12-mer peptide encompassing the 35-46 sequence of the beta 1 domain of the MHC class II molecule. CD4low HUT78 T cell adhesion to B cells was stable over 60 min, whereas expression of CD4 led to a transient adhesion. In addition, adhesion of CD4+ T cells to MHC class II- B cells was also stable. The CD4-dependent alteration of adhesion required the association of CD4 with p56lck because expression of mutant forms of CD4 unable to bind p56lck resulted in a lack of CD4-dependent regulation of adhesion. Herbimycin A, an inhibitor of tyrosine kinase activity, reversed the effect of CD4 transfection on adhesion. These results indicate that ligand binding to CD4 delivers a signal-inducing cell dissociation by activating p56lck tyrosine kinase. This regulatory pathway may provide a quick and reliable way for multiple and subsequent Ag-independent adhesion events of CD4+ T cells.
Signal transduction mediated by the reconstituted IL-2 receptor. Evidence for a cell type-specific function of IL-2 receptor beta-chain.
Authors: Minami Y , Oishi I , Liu Z J , Nakagawa S , Miyazaki T , Taniguchi T 
Published: December 2022

Abstract
The binding of IL-2 to its specific receptor (IL-2R) triggers various cellular events including the induction of nuclear proto-oncogenes (c-fos, c-jun and c-myc genes) and the proliferation of hemopoietic cells. In the present study, we have established NIH 3T3 fibroblasts in which the three IL-2R subunits, the alpha-chain (IL-2R alpha), the beta-chain (IL-2R beta), and the gamma-chain (IL-2R gamma), are constitutively expressed. The resulting cell lines express high affinity IL-2R on their cell surface at levels comparable with those of IL-2-responsive lymphoid cells. We observed that the high affinity IL-2R in NIH 3T3 fibroblasts can mediate the IL-2-stimulated tyrosine phosphorylation of p42/p44 (mitogen-activated protein kinase) and the induction of the c-fos, c-jun and c-myc genes. In NIH 3T3 fibroblasts the high affinity IL-2R bearing a deletion of a region rich in acidic amino acids (the "acidic" region) in the IL-2R beta-chain failed to induce the tyrosine phosphorylation of MAP kinase as well as the expression of the all three nuclear proto-oncogenes. On the other hand, our previous studies had demonstrated that the high affinity IL-2R bearing the same mutant IL-2R beta-chain retained the ability to induce c-myc gene in response to IL-2 in a murine IL-3-dependent pro-B cell line, BAF/B03. Hence, these results reveal the underlying complexity of signal transduction among different cell types. The inability of the reconstituted high affinity receptor to mediate the IL-2-induced proliferation of NIH 3T3 fibroblasts suggests that induction of the three nuclear proto-oncogenes and the tyrosine phosphorylation of mitogen-activated protein kinase in NIH 3T3 fibroblasts are not sufficient to induce cellular proliferation.
Structure, chromosomal localization, and methylation pattern of the human mb-1 gene.
Authors: Ha H , Barnoski B L , Sun L , Emanuel B S , Burrows P D 
Published: December 2022

Abstract
The Ag receptor on B lymphocytes is a multimeric complex that is composed of an Ag-specific component, surface Ig, which is noncovalently associated with at least two other proteins, Ig alpha and Ig beta. These are the glycoprotein products of the B lineage-restricted mb-1 and B29 genes and are crucial for the cell surface expression and function of the Ag receptor on B lymphocytes. To better understand the regulation of mb-1, we have cloned and sequenced a 5.7-kb genomic DNA fragment that contained the human gene. The overall structure of human mb-1 is very similar to that of the murine gene, including the number and approximate size of exons. The promoter region lacks a TATA element, but contains two copies of an early B cell factor-binding motif, which previously has been shown to be important for murine mb-1 expression. Other structural features include two nuclear factor-kappa B binding sites at the 5' end of the gene and a long stretch of AG rich-sequence between exons 3 and 4, downstream of an Alu repeat sequence that contains a potential stem-loop structure. The mb-1 gene was localized to chromosome 19q13.2-13.3 by a combination of two methods, PCR amplification of DNA from a somatic cell hybrid-mapping panel and fluorescence in situ hybridization. An examination of the methylation pattern revealed a striking correlation between demethylation in the 5' region of the gene and expression of mb-1. The demethylated HpaII/MspI sites are adjacent to the nuclear factor-kappa B-binding motifs, which suggests a role for this transcription factor in the regulation of human mb-1 gene expression.
Distinct effects of human herpesvirus 6 and human herpesvirus 7 on surface molecule expression and function of CD4+ T cells.
Authors: Furukawa M , Yasukawa M , Yakushijin Y , Fujita S 
Published: December 2022

Abstract
This study was undertaken to investigate the effects of newly isolated T lymphotropic viruses, human herpesvirus (HHV)-6 and HHV-7, on CD4+ T cells. We first examined changes in surface molecule expression on CD4+ T cells after infection with HHV-6 or HHV-7 by flow cytometry. Among surface molecules examined, CD3 expression appeared to decline markedly after infection with HHV-6 variant A (strain U1102) but the decreased level of CD3 expression after infection with HHV-6 variant B (strain Z29) was slight. Impairment of surface CD3 expression on HHV-6 variant A-infected cells was also demonstrated by measuring intracellular free Ca2+ concentration in response to anti-CD3 mAb. In contrast, HHV-7 infection induced a marked loss of surface CD4 expression, but the decline of CD3 expression was slight. Cytotoxic activity of virus-specific CD4+ CTL clones decreased after infection with both HHV-6 variant A or HHV-7 but the degree of reduction of cytotoxicity by HHV-6 variant B was not significant. Addition of lectin restored the cytotoxicity of HHV-7-infected CTL but not that of HHV-6 variant A-infected CTL. Northern blot analysis and immunoprecipitation showed that infection with HHV-6 and HHV-7 did not affect the transcription and protein synthesis of CD3 and CD4. These findings suggest that both HHV-6 and HHV-7 may directly cause T cell immunodeficiency but that the mechanisms of CD4+ T cell dysfunction mediated by HHV-6 and HHV-7 are different.
Administration of recombinant human IL-7 to mice alters the composition of B-lineage cells and T cell subsets, enhances T cell function, and induces regression of established metastases.
Authors: Komschlies K L , Gregorio T A , Gruys M E , Back T C , Faltynek C R , Wiltrout R H 
Published: December 2022

Abstract
These studies investigate the effects of exogenously administered recombinant human IL-7 (rhIL-7) on mouse leukocyte subsets in vivo in normal and tumor-bearing mice. The administration of rhIL-7 to normal mice caused a pronounced leukocytosis (three- to fivefold increase over background) in the spleen and lymph nodes, with B-lineage and T cells, NK cells, and macrophages all being increased. CD8+ T cells increased disproportionately, such that the CD4 to CD8 ratio decreased dramatically. The rhIL-7-induced effects were dose-dependent, increased with duration of treatment, and were reversible after cessation of rhIL-7 administration. T cell number increases after rhIL-7 treatment were primarily a result of an expansion of the peripheral T cell population. Importantly, splenocytes from rhIL-7-treated mice have enhanced proliferative responses to various T cell stimuli in vitro and were able to potentiate an allogeneic CTL response in vivo. The rhIL-7-induced changes in T cell number and the CD4 to CD8 ratio also were observed in mice bearing early Renca renal adenocarcinoma pulmonary metastases, and these changes coincided with up to a 75% reduction in pulmonary metastases. Overall, these results demonstrate that the administration of rhIL-7 to mice profoundly increases the number of B and T cells, and reduces the number of pulmonary metastases. The results also suggest that IL-7 may be useful for restoring lymphoid subsets in immunosuppressed hosts and in enhancing T cell-mediated immune responses. Such effects may be useful in the treatment of microbial diseases and cancer.
Monoclonal antibody to an activation neoepitope of alpha M beta 2 inhibits multiple alpha M beta 2 functions.
Authors: Elemer G S , Edgington T S 
Published: December 2022

Abstract
alpha M beta 2, a beta 2 integrin expressed on cells of myelomonocytic differentiation, functions as a receptor for factor X (X) and fibrinogen (Fg) and participates in leukocyte adhesion to vascular endothelium. Acquisition of high affinity ligand binding has been suggested to result from a conformational change of alpha M beta 2 in response to agonist-induced leukocyte stimulation. We now describe mAb 7A10, which preferentially binds to alpha M beta 2 on activated cells and reports the functional activation of this integrin. Agonist-stimulated monocytes and monocytic cells, but not resting cells, maximally expressed the 7A10 neoepitope, whereas expression of other selected alpha M beta 2 epitopes remained unchanged. The neoepitope was elicited equally by exposure of cells to either ADP or FMLP and did not require divalent cations for expression. Saturation of the 7A10 neoepitope by this Ab on stimulated THP-1 cells inhibited both X and Fg binding and abolished the alpha M beta 2-driven cellular coagulant response. Stimulated monocytic cells, which bound X and/or Fg, exhibited a sustained adhesion to unstimulated endothelial cell monolayers and Ab 7A10 inhibited this sustained adhesion. We conclude that activated conformers of alpha M beta 2 mediate X and Fg binding, that assembly of either X or Fg or both on alpha M beta 2 mediates leukocyte adhesion to unstimulated endothelium through sparse ICAM-1, and that mAb 7A10 can report and functionally inhibit this pathway of leukocyte adhesion.
Pathogenesis of hyperacute experimental autoimmune myasthenia gravis. Acetylcholine receptor/cholinergic site/receptor function/autoimmunity.
Authors: Mihovilovic M , Donnelly-Roberts D , Richman D P , Martinez-Carrion M 
Published: December 2022

Abstract
Three mAbs, mAbs 249E, 370, and 383C, directed against the alpha-bungarotoxin (alpha BgTx) binding site of the acetylcholine receptor (AChR) induce a hyperacute form of experimental autoimmune myasthenia gravis (EAMG), characterized by death within hours of mAb injection. To analyze the mechanisms of this effect, purified AChR-mAb complexes were investigated for their ability to bind the cholinergic agonist carbamoylcholine and to undergo agonist-induced activation of the cholinergic ionophore. The three mAbs inhibited carbamylcholine binding, and, conversely, their binding to AChR was inhibited by carbamylcholine. All three completely inhibited carbamylcholine-induced T1+ influxes to AChR-rich vesicles. These data indicate that the severe hyperacute EAMG induced by these mAbs results from blockage of AChR function and that the role of such potent Abs (even if present in small amounts) in the pathogenesis of human myasthenia gravis deserves further investigation.
Complement activation by recombinant HIV-1 glycoprotein gp120.
Authors: Süsal C , Kirschfink M , Kröpelin M , Daniel V , Opelz G 
Published: December 2022

Abstract
The mechanism of CD4+ cell depletion in HIV-infected patients is poorly understood. In this study we investigated whether rgp120 can activate the complement system in the absence of anti-gp120 Abs. We found that the complement proteins C4, C3d, C5b-9, and properdin bind to rgp 120-coated CD4+ T cells of healthy individuals when incubated in autologous serum. Activation of the complement system occurred primarily via the classical pathway and was abolished in sera deficient in C1q and C4 as well as in the presence of EDTA. No cell lysis was observed in a lymphocytotoxicity assay using human serum, possibly because of homologous restriction of complement lysis. In contrast, addition of rabbit sera induced lysis of the rgp 120-precoated cells. Cell lysis by rabbit serum was found to be because of naturally occurring IgM anti-gp 120 Abs. The rgp 120, which was immobilized on the surface of microtiter plates activated complement in the absence of lymphocytes. Complement activation by cell-bound HIV-1 envelope glycoprotein gp120 with subsequent opsonization may be relevant for the elimination of noninfected CD4+ T cells in HIV-infected patients.
TAP (transporter associated with antigen processing)-independent presentation of endogenously synthesized peptides is enhanced by endoplasmic reticulum insertion sequences located at the amino- but not carboxyl-terminus of the peptide.
Authors: Bacik I , Cox J H , Anderson R , Yewdell J W , Bennink J R 
Published: December 2022

Abstract
Under most circumstances, cell surface MHC class I molecules display peptides derived from a cytosolic pool of proteins. The efficient presentation of such peptides requires the functioning of two MHC gene products [TAP1 and TAP2 (transporter-associated with Ag processing 1 and 2)] that form a complex that facilitates transmembrane movement of peptides from the cytosol to the endoplasmic reticulum, the site of peptide association with class I molecules. It has been previously shown that peptides can be presented in a TAP-independent manner in association with HLA A2.1 or H-2 Kd if they are expressed COOH-terminal to an endoplasmic reticulum insertion/signal sequence derived from the adenovirus E3/19K glycoprotein (Anderson et al., 1991. J. Exp. Med. 174: 489; Eisenlohr et al., 1992. Cell 71: 963). We show that: 1) the E3/19K signal sequence greatly enhances the presentation of each of four additional peptides tested in association with H-2 Kb or Kk, 2) the E3/19K signal sequence can be substituted by a signal sequence derived from beta-IFN, and 3) the E3/19K signal sequence does not function when located at the COOH terminus of antigenic peptides. These findings indicate that first, many peptides require TAP for efficient presentation to T cells, second, expression of peptides COOH-terminal to signal sequences is a generally applicable method of bypassing the TAP-dependence of peptide presentation and third, the leader sequence does not act to bypass TAP simply by increasing the hydrophobic nature of peptides.
Effect of anti-CD4 on CD4 subsets. I. Anti-CD4 preferentially deletes resting, naive CD4 cells and spares activated CD4 cells.
Authors: Chace J H , Cowdery J S , Field E H 
Published: December 2022

Abstract
Anti-CD4 has been extensively studied in murine models of autoimmunity and transplantation. The timing of anti-CD4 administration in these systems is critical because anti-CD4 effectively blocks primary T-dependent responses but does not diminish ongoing or memory responses in immunized animals. These differential effects suggest that anti-CD4 suppresses a subpopulation of CD4+ cells. We previously observed in vitro that simultaneous activation through TCR-T3 rescued CD4+ cells from anti-CD4 elimination. From this we hypothesized that activated CD4+ cells resisted the effects of anti-CD4. We now show that in vivo treatment with anti-CD4 preferentially eliminated resting, naive CD4+ cells rather than memory and effector CD4+ cells. The CD4+ cells that remained after anti-CD4 treatment exhibited evidence of recent activation, because a higher percentage expressed IL-2R, regardless of subset phenotype. Moreover, Mls-1-primed, anti-CD4-treated mice showed a higher percentage of V beta 6+ (Mls-1 reactive) CD4+ cells than either unprimed mice, anti-CD4-treated mice, or Mls-1-primed controls, implicating the importance of recent activation. These anti-CD4-resistant cells also retained their functional abilities. T cells from BALB/c mice treated with anti-CD4 after Mls-1 immunization maintained their MLR proliferation against DBA/2 stimulator cells. In addition, anti-CD4 did not reduce T-dependent antibody responses in mice previously primed against the Ag cholera toxin or SRBC. Thus, activated CD4+ cells resist the suppressive effects of anti-CD4. Our findings have critical implications for the ongoing clinical trials using anti-CD4.
Monocytes provide a novel costimulatory signal to T cells that is not mediated by the CD28/B7 interaction.
Authors: Johnson J G , Jenkins M K 
Published: December 2022

Abstract
Resting CD4+T cells must receive nonspecific costimulatory signals from APC to produce maximal amounts of IL-2 in response to TCR signaling. The T cell-specific surface molecule CD28 is one protein that transduces a costimulatory signal following interaction with its ligand B7. We report here the identification of another contact-mediated costimulatory signal provided by the human histiocytic line U937 and by purified monocytes. Although this monocyte-derived costimulus is not transduced by the CD28/B7 interaction, it synergizes with the CD28 signal to elicit maximal IL-2 production from freshly isolated T cells. IL-2 production by previously activated CD8+ T cells depends on the monocyte-derived costimulatory signal, although memory CD4+ T cells respond well to either the monocyte-derived costimulus or B7-derived costimulation. In contrast, IL-2 secretion by naive T cells appears to require the synergistic interaction between both costimulatory pathways. These results suggest that the array of costimulatory ligands expressed by various APC affects the magnitude of the T cell response and also which T cell subsets are stimulated.
Long term activation of natural killer cells results in modulation of beta 1-integrin expression and function.
Authors: Mainiero F , Gismondi A , Milella M , Morrone S , Palmieri G , Piccoli M , Frati L , Santoni A 
Published: December 2022

Abstract
Integrin expression and function is largely modulated by cell activation. Here we provide evidence that long term activation of human NK cells results in a marked modulation of beta 1-integrin expression and adhesive functions. By flow cytometry and immunochemical analysis we have detected induction of alpha 1 beta 1 and alpha 2 beta 1, increased expression of alpha 4 beta 1 and alpha 5 beta 1, and decline of alpha 6 beta 1 on CD3-CD56+ NK cells generated from 10-day coculture of nonadherent PBMC with irradiated RPMI 8866 EBV+ lymphoblastoid B cell line. Adhesion assays performed on extracellular matrix-coated plates showed that, unlike fresh NK cells, long term-activated NK cells bind to native collagen I via alpha 2 beta 1 and to heat-denatured collagen I in an RGD-dependent manner, although they lose the ability to bind to laminin. In regard to the adhesion to FN, no major quantitative changes are observed after long term NK cell activation. However, whereas alpha 4 beta 1 and alpha 5 beta 1 completely mediate the adhesion of fresh NK cells to fibronectin, binding of activated NK cells is only partially beta 1-dependent and seems to involve also non-beta 1-integrin(s) recognizing and RGD sequence. The modulation of beta 1-integrin expression and the acquisition of new adhesive properties on long term-activated NK cells may be relevant for their traffic and tissue localization during inflammation and immune response.