bluuebunny/crossref_metadata_2025_split huggingface dataset:
The native structure of intercellular adhesion molecule-1 (ICAM-1) is a dimer. Correlation with binding to LFA-1.
Authors: Reilly P L , Woska J R , Jeanfavre D D , McNally E , Rothlein R , Bormann B J 
Published: January 2023

Abstract
In solution, intercellular adhesion molecule-1 (ICAM-1) exhibits extremely low affinity for its receptor, LFA-1, as direct binding to LFA-1 has not been reported. Furthermore, there are conflicting reports on the ability of ICAM-1 in solution to inhibit cell adhesion events. These differences could be due to the valency or an oligomeric native biochemical form of membrane-bound and soluble ICAM-1, which may correlate with its ability to bind to integrins. To test this, stimulated adenocarcinoma (A549) cells or HUVEC were labeled with 35S-methionine/cysteine and treated with a chemical cross-linker. A high m.w. form (200 kDa) of ICAM-1 but not ICAM-2 was specifically immunoprecipitated from cross-linked cell lysates and supernatants. Affinity purification of crosslinked supernatants revealed that the majority of ICAM-1 was dimeric as opposed to recombinant soluble ICAM-1, which contains a minor fraction of dimer. Gel filtration chromatography was used to isolate monomeric and dimer-rich fractions of recombinant soluble ICAM-1, and tested for direct binding to affinity-purified LFA-1. Dimer-rich fractions demonstrated an enhanced ability and estimated affinity, compared with monomeric protein, to bind to purified LFA-1. These data suggest that ICAM-1 exists in its native membrane-bound and shed form as a non-covalent dimer, and that dimerization directly correlates with enhanced binding to LFA-1.
Interference with thymocyte differentiation by an inhibitor of S-adenosylhomocysteine hydrolase.
Authors: Benveniste P , Zhu W , Cohen A 
Published: January 2023

Abstract
Adenosine deaminase (ADA) deficiency causes severe combined immune-deficiency disease in humans. It is believed that the accumulation of the ADA substrate deoxyadenosine affects T cell development through interference with deoxynucleotide metabolism and/or S-adenosylmethionine-mediated methylation processes. In this study, we used a specific inhibitor of methylation, (Z)-5'-fluoro-4',5'-didehydro-5'-deoxyadenosine (FddA), to study the effect of inhibition of methylation on intrathymic T cell development in a murine model for ADA deficiency. FddA causes inhibition of thymocyte differentiation specifically at the CD8low and CD4CD8 double-positive stages. This inhibition is not due to induction of apoptosis, rather it is a result of specific inhibition of regulation of the levels of the mRNAs coding for TCR and CD4 and CD8 co-receptor molecules that normally occurs at these stages of thymocyte differentiation. We hypothesize that the transcription of these T cell-specific molecules is regulated by a common developmental stimulus involving a S-adenosylmethionine-mediated methylation step. Identification of this step will help in understanding the role of methylation in intrathymic differentiation and will also provide a molecular explanation for the tissue and developmental stage specificity observed in severe combined-immune-deficient patients with ADA deficiency.
Activation of B lymphocyte maturation by a human follicular dendritic cell line, FDC-1.
Authors: Clark E A , Grabstein K H , Gown A M , Skelly M , Kaisho T , Hirano T , Shu G L 
Published: January 2023

Abstract
Previously, we described the characteristics of a cell line that is derived from a low density fraction of human tonsillar cells and, on the basis of a number of criteria, is related to follicular dendritic cells (FDC). This line, FDC-1, binds B lymphocytes and not T lymphocytes, and promotes anti-Ig- or anti-CD40-induced B cell proliferation. In this work, we show that culturing B cells with small numbers of FDC-1 cells leads to significant production of IL-6 and of both IgM and IgG. As few as 50 to 100 FDC-1 augmented B cell IgM production by 10- to 100-fold. Although fixed FDC-1 cells, unlike live FDC-1 cells, do not stimulate Ig production, cell contact is not required for all FDC-dependent Ig production. Supernatants from cultured FDC-1 cells can also stimulate B cells to produce IgM, suggesting that FDC produce a soluble B cell stimulating factor(s). Augmentation of FDC-dependent IgM production by either IL-6 or IL-7 and augmentation of FDC-dependent IgG production by IL-4 does require FDC-1 cells to be in contact with B cells. When the effects of FDC-1 cells were compared with those of epithelial cell lines and human foreskin fibroblasts (HFF), both FDC-1 cells and HFF induced B cells to produce IgM. FDC-1, unlike HFF, were positive for CD40, CD54, CD73, CD74, and nerve growth factor receptor (NGFR), and unlike HFF, but like certain stromal cells, FDC-1 cells also expressed smooth muscle actin, and a novel marker for stromal cells, BST-1. The possible relationship of FDC-1 cells and FDC in general to a fibroblast/stromal cell lineage is discussed.
Efficient internalization of MHC class II-invariant chain complexes is not sufficient for invariant chain proteolysis and class II antigen presentation.
Authors: Swier K , Miller J 
Published: January 2023

Abstract
In Ag-presenting cells, MHC class II molecules bind antigenic peptides in endocytic compartments and transport them to the cell surface for presentation to CD4+ T cells. Newly synthesized class II alpha beta heterodimers associate with a third polypeptide, invariant chain (Ii), in the endoplasmic reticulum. This association may prevent class II molecules from binding peptides until they are transported to endocytic compartments where Ii is proteolyzed. Signals in the Ii cytosolic tail are believed to be responsible for the targeting of class II-Ii complexes to endocytic compartments, but it is unclear whether this targeting event occurs at the trans face of the Golgi or at the plasma membrane. In this report, we address whether the endosomal localization signal in the Ii cytosolic tail can be functionally substituted with a tyrosine-based signal for rapid internalization from the cell surface. A chimeric protein was generated in which the Ii cytosolic tail was replaced in its entirety with the cytosolic tail from transferrin receptor. In cells expressing this chimeric form of Ii, newly synthesized class II-Ii complexes travel rapidly to the cell surface and are internalized efficiently, but Ii proteolysis is delayed and class II Ag presentation is inhibited. These results suggest that targeting class II-Ii complexes to early/recycling endosomes from the cell surface does not in itself lead to Ii proteolysis; subsequent delivery to later endosomes may be required. The data suggest that signals for this targeting event may lie in residues 18 to 29 of the Ii cytosolic tail.
Lack of strict correlation of functional sensitization with the apparent affinity of MHC/peptide complexes for the TCR.
Authors: al-Ramadi B K , Jelonek M T , Boyd L F , Margulies D H , Bothwell A L 
Published: January 2023

Abstract
We describe a comprehensive analysis of the effect of avidity of TCR-MHC/peptide interaction on activation of the (p2Ca). In study, monosubstituted variants of p2Ca were used and assessed for binding to purified H-2Ld, binding of H-2Ld/peptide complexes to sTCR, and ability to activate 2C cells to two independent effector functions. Among the &gt; 20 variants analyzed, functional activity of most peptides that bound the MHC well correlated with the strength of interaction of MHC/peptide complexes with sTCR. However, with some variants, a clear discordance between the apparent TCR-MHC/peptide affinity and biologic function was observed, demonstrating that the former cannot always be gauged by the latter. In the case of L4 peptide (phenylalanine at position 4 substituted with leucine), peptide/MHC complexes showed no detectable binding to sTCR, indicating a 10-fold or greater decrease in affinity. Nevertheless, this peptide sensitized target cells for lysis at a level equivalent to the parental peptide. A clearer understanding was revealed by studying the extent to which activation by variant peptides was dependent on CD8. Our data indicate that resistance to anti-CD8 mAb blocking correlates with strong binding affinity between sTCR and MHC/peptide complexes. These data suggest that, for the activation of CTL function, the absolute level of intrinsic affinity of TCR for MHC/peptide ligand is not a single critical determinant, but rather, that activation is governed by the compound influence of several factors, which ensures a minimum threshold of intracellular triggering is reached to elicit the response.
Structure and diversity of the T cell antigen receptor beta-chain in a teleost fish.
Authors: Partula S , de Guerra A , Fellah J S , Charlemagne J 
Published: January 2023

Abstract
Cell-mediated immunity (e.g., allograft rejection) is found in all vertebrates, and these reactions are known to depend on thymus-derived cells in amphibian, avian, and mammalian species. The participation of peripheral T cell-like lymphocytes subpopulations to fish immunity is now well documented, but the developmental origin, migration, and peripheral tissue distribution of these cells remain practically unknown. This is mainly due to the difficulty of efficiently thymectomizing fish at an early stage of development and to the lack of Ab strictly specific for thymocytes and T cell surface Ag. One strategy for analyzing T cell biology in fish would be to characterize the genes encoding polypeptides homologous to the TCR molecules. This report describes cDNA clones from the rainbow trout (Oncorhynchus mykiss) that have sequences very similar to amphibian, avian, and mammalian TCR beta-chains. Three complete trout V beta segments belonging to different families were analyzed; one of them had limited amino acid sequence similarity to the human V beta 20 family. The 10 trout beta-chain-joining segments all retain the invariant mammalian J beta residues, and comparison of 66 V beta-J beta junctions led to the identification of a D beta-like sequence (GGACAGGG) that is shorter than but very similar to the chicken D beta and mammalian D beta 1 sequences. There is considerable diversity at the V beta-D beta and D beta-J beta junctions, suggesting the presence of N-nucleotides. The trout C beta extracellular domain is shorter than mammalian C beta, and the hinge region has no cysteine residue. The transmembrane C beta domain contains a lysine residue that in mammals is thought to be involved in charged interactions with members of the CD3 complex.
Dimeric and tetrameric IgA are transcytosed equally by the polymeric Ig receptor.
Authors: Song W , Vaerman J P , Mostov K E 
Published: January 2023

Abstract
Polymeric IgA (pIgA) is transcytosed across epithelial cells and into external secretions by the polymeric Ig receptor (pIgR). Binding of dimeric IgA (dIgA) to the pIgR stimulates transcytosis of the pIgR. The pIgA in secretions is found as dimers (dIgA) and higher polymers, such as tetramers (tIgA), but little is known of the functional significance of the different sizes. Here we compared the ability of dIgA and tIgA to perform three functions that are essential to their transport into mucosal secretions. 1) Equilibrium binding studies showed that there were twice as many binding sites for tIgA as dIgA at the basolateral cell surface, but that the affinity of these sites for tIgA was one-half of that for dIgA. 2) Both dIgA and tIgA were rapidly transcytosed by the pIgR, although transcytosis of tIgA was slower. 3) Both dIgA and tIgA could stimulate transcytosis of the pIgR, although tIgA was less effective. The possible implications of these findings for the relative biologic roles of dIgA and tIgA are discussed.
Co-segregation of tumor immunogenicity with expression of inducible but not constitutive hsp70 in rat colon carcinomas.
Authors: Ménoret A , Patry Y , Burg C , Le Pendu J 
Published: January 2023

Abstract
Recent results have shown the importance of heat-shock proteins (hsp) in immune reactions. In addition, immunization against hsp purified from some immunogenic tumors specifically protects animals from a challenge with the tumor from which the hsp were purified. The protection is dependent on the association between hsp and immunogenic peptides. Using a model of rat colon carcinoma, we studied the importance of hsp70 expression in determining the tumorigenicity of cancer cells in immunocompetent syngeneic animals. Various clones with distinct tumorigenic potentials have been derived from the same parental tumor. Some clones are tumorigenic and others are rejected through an immune-based mechanism. It was observed that among all parameters tested, immunogenicity of tumors co-segregated with expression of inducible hsp70 but not with constitutive hsc70. Variants were obtained from a highly tumorigenic clone (PROb) and from a regressive clone (REGb). The PROb variant (Ph8), selected by repeated sublethal heat shocks, showed an increased capacity for hsp70 synthesis concomitant with a decreased tumorigenicity. Inversely, the REGb variant (REGR73), selected after in vivo growth in partially immunosuppressed rats, acquired tumorigenicity and lost the ability to synthesize hsp70. Expression of other immunologic mediators such as intercellular adhesion molecule-1, MHC I, and MHC II did not co-segregate with tumor immunogenicity. Depletion experiments showed that the immunity elicited by these tumors involves TCR-alpha beta-bearing T cells. Such observations imply that, in this experimental model, inducible but not constitutive hsp70 is involved in immunogenicity of tumors.
IL-12 prevents mortality in mice infected with Histoplasma capsulatum through induction of IFN-gamma.
Authors: Zhou P , Sieve M C , Bennett J , Kwon-Chung K J , Tewari R P , Gazzinelli R T , Sher A , Seder R A 
Published: January 2023

Abstract
Histoplasma capsulatum is a pathogenic fungus found in discrete geographic locations throughout the world. The fungus invades the reticuloendothelial organs such as the spleen and liver of immunocompetent hosts where it is usually controlled. However, in individuals with immune deficiency, histoplasmosis is a severe and potentially fatal disease. Resistance to this infection is due primarily to a cellular immune response mediated by T cells and macrophages. Moreover, IFN-gamma is critical in activating macrophages to kill the organism. Herein we study the regulation of cytokine induction in mice infected with H. capsulatum and the effects of IL-12 in the course of infection. Mice infected with H. capsulatum and treated with neutralizing Abs to IFN-gamma, TNF-alpha, or IL-12 experienced accelerated mortality, indicating that endogenous production of these cytokines plays an important role in response to infection. In contrast, mice treated with IL-12 or a neutralizing Ab to IL-4 at the initiation of infection had substantially diminished mortality. Moreover, mice infected and treated with IL-12 show a two- to threefold increase in the amount of IFN-gamma following in vitro stimulation with specific H. capsulatum Ag compared with the control infected mice. The protective effect of IL-12 could be abrogated if a neutralizing Ab to IFN-gamma was given at the same time, demonstrating that the role of IL-12 in protection was mediated by IFN-gamma. Additionally, infected mice treated with IL-12 had a severalfold decrease in the colony counts of H. capsulatum in spleen cells after 5 days of infection as compared with control animals. Lastly, spleen cells from infected animals treated with IL-12 showed a striking decrease in their proliferative response to mitogen or H. capsulatum Ag. Responses could be restored by adding inhibitors of IFN-gamma or of nitric oxide to the in vitro cultures. The above observations suggest that IL-12 may be useful in immunologic intervention against this opportunistic pathogen.
CD38-mediated ribosylation of proteins.
Authors: Grimaldi J C , Balasubramanian S , Kabra N H , Shanafelt A , Bazan J F , Zurawski G , Howard M C 
Published: January 2023

Abstract
The lymphocyte cell-surface Ag CD38 catabolizes NAD to adenosine 5' diphosphoribose (ADPR) and cyclic ADPR (cADPR). We show here that the soluble extracellular domain of CD38 (sCD38) mediates ADP ribosylation of several proteins. This was demonstrated by mass spectrometric analyses which revealed the addition of mass in units of 541.1 Da to these proteins, presumably corresponding to the covalent attachment of one or more ADPR moieties. Separate experiments showed that the same proteins became specifically radiolabeled following incubation with [32P]NAD plus sCD38. Additionally, it is shown that sCD38 can autoribosylate. Moreover, sCD38-mediated protein ribosylation was found to occur specifically at cysteine residues, since it was effectively blocked by addition of L-cysteine but not by other amino acids, and CD38-mediated protein ribosylation could be reversed by the addition of HgCl2, which specifically cleaves thiol-glycosidic bonds. ADPR purified from the reaction of sCD38 with NAD could itself be covalently transferred to target proteins at rates similar to the sCD38-mediated reaction, indicating that the ribosylation proceeds via the generation of this reactive intermediate. In vitro mutagenesis of a catalytic Glu residue that is conserved in numerous ADP-ribosyl transferases revealed that this amino acid is also important for catalysis in CD38. These data suggest that CD38 has the potential to cause ribosylation of experimental proteins, and raises the possibility that its specific ribosylation of a currently unidentified lymphocyte protein may contribute to its array of immunoregulatory activities.
Activation of the classical pathway of complement by tobacco glycoprotein (TGP).
Authors: Koethe S M , Nelson K E , Becker C G 
Published: January 2023

Abstract
Tobacco glycoprotein (TGP), a polyphenol-rich glycoprotein isolated from tobacco leaves, activates the classical complement pathway through a mechanism that appears to involve direct interaction with C1q. A binding site on C1q for TGP can be localized by competitive inhibition with DNA to a region located in the junction between the collagen-like and globular regions of the molecule. A protein with activity similar to TGP has also been isolated from cigarette smoke condensate (TGP-S); it shares a binding site on C1q with TGP and has similar functional activity, with the exception that complement activation does not proceed to formation of a C3 cleaving enzyme. The ability of TGP and TGP-S to activate complement can be partially duplicated using polyphenols associated with tobacco leaf and smoke, i.e., chlorogenic acid and rutin. These polyphenols also compete with TGP for a binding site on immobilized C1q, suggesting that the polyphenol portion of TGP is critical for activation of complement. These results provide an additional mechanism for complement activation by cigarette products that, in vivo, could result in a localized complement depletion, generation of biologically active complement cleavage products, and initiation of an inflammatory response.
IL-4 promotes macrophage development by rapidly stimulating lineage restriction of bipotent granulocyte-macrophage colony-forming cells.
Authors: Nicholls S E , Heyworth C M , Dexter T M , Lord J M , Johnson G D , Whetton A D 
Published: January 2023

Abstract
Granulocyte macrophage colony-forming cells (GM-CFC) are bipotential progenitor cells that can proliferate and develop into macrophages in response to macrophage CSF or into neutrophils in response to stem cell factor or granulocyte CSF. These cytokines promoted growth and development in highly enriched GM-CFC. In [3H]thymidine suicide assays, IL-4 was shown to stimulate proliferation of GM-CFC to the same degree as IL-3 and other potent mitogens for GM-CFC. IL-4 also maintained the clonogenic potential of enriched GM-CFC over a 2-day period. However, after several days in the presence of IL-4, the GM-CFC began to die and retained blast cell morphology characteristic of the isolated GM-CFC. When a high concentration of IL-4 was added to GM-CFC with neutrophilic stimuli, the response of these cells was altered because macrophages were formed. This effect was achieved by a 4-h preincubation with IL-4, suggesting that an early signal produced by IL-4 promotes lineage restriction, although IL-4 itself cannot promote development. IL-4, like macrophage CSF, translocates PKC-alpha to the nucleus in GM-CFC, this redistribution of protein kinase C alpha (PKC-alpha) being inhibited by calphostin C (a PKC inhibitor). Calphostin C also blocked IL-4-mediated development of macrophages in stem cell factor- and granulocyte-CSF-treated cells. This is further evidence that PKC-alpha translocation is involved in the commitment of GM-CFC to macrophage development. This data also suggests that agonist-stimulated lineage commitment can be uncoupled from development in normal hematopoietic cells.
Fibrin activation of vascular endothelial cells. Induction of IL-8 expression.
Authors: Qi J , Kreutzer D L 
Published: January 2023

Abstract
Fibrin deposition and leukocyte accumulation are classic histopathologic hallmarks of acute and chronic inflammation. Although both of these processes are common to inflammatory processes, surprisingly little is known about the interrelationship between fibrin deposition and leukocyte accumulation. We hypothesized that: 1) fibrin can regulate inflammation by directly inducing leukocyte chemotactic factor (LCF) expression from vascular endothelial cells (VEC), and 2) this fibrin-induced VEC expression of LCF would enhance leukocyte recruitment seen in acute and chronic inflammation. To test this hypothesis, we developed an in vitro model system of in situ polymerization of fibrin on isolated bovine pulmonary artery endothelial cells in culture. In the initial phase of our studies, we found that fibrin induced a time- and dose-dependent expression of leukocyte migration activity from VEC. Checkerboard analysis demonstrated that the leukocyte migration activity present in the fibrin-stimulated VEC culture supernatant was truly chemotactic in nature. In an effort to begin to characterize this chemotactic activity, we demonstrated that this fibrin-induced LCF activity was 1) protein dependent, 2) not derived from fibrin(ogen), and 3) had an apparent m.w. of 6 to 12 kDa. Our further studies demonstrated that fibrin was a potent stimulus for IL-8 Ag expression from the VEC. Thus, these studies clearly demonstrate that fibrin has the capability to induce leukocyte chemotactic activity in general, and IL-8 activity specifically, from VEC. These studies support our hypothesis that fibrin is an important activator of vascular endothelial cells in vivo.