bluuebunny/crossref_metadata_2025_split huggingface dataset:
Protection against autoimmune diabetes in mixed bone marrow chimeras: mechanisms involved.
Authors: Mathieu C , Casteels K , Bouillon R , Waer M 
Published: December 2022

Abstract
After bone marrow transplantation, complete nonobese diabetic (NOD) into (NOD x C57Bl/10)F1 chimeras developed insulitis in 100% (7/7) and diabetes in 58% (7/12) of cases. In contrast, when mixed chimerism was induced, a near complete protection against insulitis (3/23, p &lt; 0.0001 vs complete chimeras) and diabetes (0/25, p &lt; 0.001 vs complete chimeras) was achieved even in chimeras with as few as 5% F1 cells. In cotransfer experiments, splenocytes from mixed chimeras failed to prevent diabetes, thus overruling a role for suppressor cells in protection. Whereas splenocytes from complete chimeras transferred diabetes into young irradiated NOD mice in all cases, NOD splenocytes from mixed chimeras only rarely transferred diabetes (3/16, p &lt; 0.01 vs complete chimeras), suggesting that the latter cells had developed tolerance toward beta cells. To achieve this tolerance, the presence of an F1 thymus was not needed. Indeed, whereas splenocytes isolated from complete chimeras were diabetogenic when transferred into neonatally thymectomized irradiated NOD recipients (3/4), they failed to induce diabetes when transferred into neonatally thymectomized irradiated F1 recipients in case again a state of mixed chimerism was induced (0/4, p &lt; 0.001 vs NOD recipients). Finally, a role for non-MHC Ags was demonstrated by experiments in F1 mice crossed between NOD and C57Bl/6, a strain congenic to C57Bl/10. Here protection against disease was only seen in the presence of high levels of F1 cells (&gt;25%). In conclusion, mixed bone marrow chimerism can induce self-tolerance in autoimmunity prone NOD immune cells. This can be achieved extrathymically but may depend on non-MHC Ags and the level of chimerism.
Polymorphism in the alpha 1 helix of the HLA-B heavy chain can have an overriding influence on peptide-binding specificity.
Authors: Barber L D , Percival L , Arnett K L , Gumperz J E , Chen L , Parham P 
Published: December 2022

Abstract
Previously, we reported overlap in the repertoires of peptides endogenously bound by a group of HLA-B allotypes related to HLA-B7. Extending such analysis to four members of the B17 family and seven members of the B15 family shows that allotypes that share sequence identity in the alpha 1 helix of the class I heavy chain possess markedly similar peptide-binding specificities. Members of the B17 family share a preference for peptides with serine, threonine, or alanine at position 2 and aromatic residues at the carboxyl terminus. Strikingly, the presence of a segment of the B17 alpha 1 helix in B*1516 and B*1517 confers the B17-like peptide-binding motif. The strong influence of natural variation in the alpha 1 helix is exemplified by the differences in peptide-binding specificity of B15 allotypes related by conversion events that replaced segments of the alpha 1 helix. In contrast, evolutionary changes that are confined to the alpha 2 domain confer less dramatic change. They do not perturb the primary anchors of the peptide-binding motif but can modulate the specificity through development and diversification of secondary anchors. Our results, in combination with those obtained previously for other HLA-B allotypes, suggest a general trend whereby polymorphism in the alpha 1 helix is the overriding influence on peptide-binding specificity of HLA-B allotypes, while amino acid substitutions in the alpha 2 domain play a more modulatory role.
Purification and characterization of the pig analogue of human membrane cofactor protein (CD46/MCP).
Authors: van den Berg C W , Pérez de la Lastra J M , Llanes D , Morgan B P 
Published: December 2022

Abstract
A panel of mAbs were raised against pig lymphocytes. Seven mAbs immunoprecipitated a 50- to 60-kDa membrane-bound protein. This protein, termed JM4C8-Ag, was expressed on a wide variety of cells, including all circulating cells and cells of fibroblast, epithelial, and endothelial origin. The JM4C8-Ag was transmembrane-anchored and glycosylated. One of the Abs was used in immunoaffinity chromatography to isolate JM4C8-Ag from erythrocyte membranes. N-terminal amino acid analysis through the first 28 residues showed a 43% homology with the human complement regulatory molecule membrane cofactor protein (MCP; CD46). The purified protein had cofactor activity for factor I-mediated cleavage of human and pig C3b, confirming its identity as the pig analogue of human MCP. The purified protein also strongly inhibited lysis of rabbit erythrocytes by human and pig complement after activation of the classical or alternative pathway. This is the first report of a nonprimate analogue of MCP. The presence of a resident MCP on pig cells capable of acting as a cofactor in the control of human complement activation has consequences for the use of pig organs in xenotransplantation.
Aggregation of low affinity IgG receptors induces mast cell adherence to fibronectin: requirement for the common FcR gamma-chain.
Authors: Dastych J , Hardison M C , Metcalfe D D 
Published: December 2022

Abstract
Mast cells have been reported to increase at sites of immune complex-induced inflammation where these cells appear to potentiate the inflammatory response. The mechanism by which mast cells accumulate at these sites is unknown. One possibility is that aggregation of low affinity IgG receptors could signal mast cells to adhere to components of the connective tissue matrix. To test this hypothesis, we first added aggregated IgG to a mast cell adhesion assay employing fibronectin as a matrix component and observed an increase in cell adhesion. Even a small amount of aggregated IgG (&lt; 60 ng/ml) demonstrated by fast protein liquid chromatography in untreated IgG preparations was sufficient to increase mast cell adhesion by 100%. We next explored the Fc gamma receptors involved. Fc gammaRII/III, which are receptors for oligomeric IgG and were first verified as present on these mast cells by FACS analysis and immunoprecipitation, signaled mast cells to rapidly adhere to fibronectin when aggregated with the anti-receptor Ab2.4G2. The adhesion process mediated by Fc gammaRII/III was not associated with beta-hexosaminidase release. Bone marrow-cultured mast cells from common gamma-chain deficient mice, unlike mast cells cultured from +/+ mice, did not respond to Fc gammaRII/III aggregation. This demonstrated requirement for a gamma-chain implicates oligomeric Fc gammaRIII in the adhesion process. Thus, aggregation of Fc gammaRIII on mast cells leads to mast cell adhesion, demonstrating a previously unknown biological function for this receptor on mast cells and providing a mechanism for mast cell accumulation in immune complex-dependent inflammation.
Human anti-nicotinic acetylcholine receptor recombinant Fab fragments isolated from thymus-derived phage display libraries from myasthenia gravis patients reflect predominant specificities in serum and block the action of pathogenic serum antibodies.
Authors: Graus Y F , de Baets M H , Parren P W , Berrih-Aknin S , Wokke J , van Breda Vriesman P J , Burton D R 
Published: December 2022

Abstract
Myasthenia gravis (MG) is a prototype Ab-mediated autoimmune disease in which Abs against nicotinic acetylcholine receptors (AChR) induce loss of functional receptors at the neuromuscular junction. Germinal centers present in MG hyperplastic thymus contain activated B cells spontaneously producing anti-human AChR (anti-huAChR) Ab in vitro. To access the anti-huAChR repertoire, phage display Fab libraries of thymic lymphocytes were constructed from two MG patients. Four Fabs highly specific for huAChR were isolated that bind to determinants in or near the main immunogenic region. These anti-huAChR Fabs showed evidence of significant somatic mutations, supporting the idea that the anti-huAChR Ab response in MG patients is driven by Ag. Two Fabs were able to inhibit up to 90% of donor serum anti-huAChR Abs. Competition with serum anti-huAChR Ab was also observed in unrelated MG patients and indicate that anti-huAChR Fabs bind to epitopes on huAChR recognized by the majority of MG patients. In vitro antigenic modulation studies demonstrated that anti-huAChR Fabs were able to induce AChR loss when cross-linked by an anti-Fab Ab but not as monovalent Fab. Moreover, anti-huAChR Fabs were able to protect against AChR loss by antigenic modulation induced by MG serum Abs, suggesting a potential therapeutic role for these recombinant Fabs in patients with a myasthenic crisis.
Construction and characterization of human CD7-specific single-chain Fv immunotoxins.
Authors: Pauza M E , Doumbia S O , Pennell C A 
Published: December 2022

Abstract
To develop novel therapeutic agents for treatment of human T cell malignancies, we constructed two single-chain Fv (sFv) immunotoxins specific for the T cell-associated Ag CD7. The sFv fragments were derived from the murine hybridomas 3A1e and 3A1f and were expressed as soluble proteins in Escherichia coli. Surface plasmon resonance analyses demonstrated that the purified 3A1e and 3A1f sFv fragments specifically bound CD7 with high affinity, 8.1 and 1.8 nM, respectively. The difference in affinity is chiefly due to a slower dissociation rate for the 3A1f sFv fragment. Despite this difference, both monovalent sFv fragments were comparably internalized by CD7+ human T leukemic cells within 30 min. These data support findings of previous studies suggesting that CD7 internalization does not require cross-linking. The sFv immunotoxins were assembled by linking ricin toxin A chain to the C termini of the sFv fragments via disulfide bonds. Both sFv immunotoxins were comparably potent in their ability to inhibit protein synthesis in vitro in CD7+ Jurkat cells (50% inhibiting concentration = 15 pM). Further preclinical studies on the use of the 3A1e and 3A1f sFv immunotoxins to treat human T cell diseases therefore appear warranted.
Endothelial cell tube formation depends on cadherin 5 and CD31 interactions with filamentous actin.
Authors: Matsumura T , Wolff K , Petzelbauer P 
Published: December 2022

Abstract
Capillary tube formation represents a specialized endothelial cell function and is a prerequisite for the establishment of a continuous vessel lumen. Tube formation is thought to depend on cell-cell adhesion molecules, but whereas cadherins, Ig superfamily proteins, and integrins have been considered as potential candidates, the specific proteins subserving this function are unknown. We identified cadherin 5 and CD31 as two molecules critical for endothelial cell tube formation. Using human dermal microvascular endothelial cells or human umbilical vein endothelial cells for an in vitro capillary tube formation assay or, for comparison, an in vivo wound healing model in SCID mice, we show that tube formation in vivo and in vitro were prevented by adhesion-blocking mAbs to both proteins when used in conjunction but not by either mAb alone. In addition, both mAbs but not each individual mAb blocked cytoplasmic filamentous actin (F-actin) reorganization that resulted in cytoplasmic F-actin clumps similar to those induced by cytochalasin D, suggesting that cadherin 5 and CD31 tune tube formation in concert with F-actin. Indeed, cytochalasin D blocked capillary tube formation but colchicine did not, the latter inhibiting microtubule but not F-actin assembly. Using immunoprecipitation methods, we show for the first time that not only cadherin 5 but also a portion of CD31 connects to beta-catenin, which is part of the adherens junction complex known to be linked to F-actin. In conclusion, we provide evidence that cadherin 5, CD31, beta-catenin, and F-actin shape a functional complex that controls endothelial cell tube formation.
Alternate splicing of mouse fusin/CXC chemokine receptor-4: stromal cell-derived factor-1alpha is a ligand for both CXC chemokine receptor-4 isoforms.
Authors: Heesen M , Berman M A , Höpken U E , Gerard N P , Dorf M E 
Published: December 2022

Abstract
Inspection of the intron splice junction of the mouse chemokine receptor fusin/CXC chemokine receptor R-4 (CXCR-4) revealed a potential in-frame alternative splice site in the region encoding the N-terminal ectodomain of the receptor. Both predicted splice products were detected by reverse transcriptase-PCR. Cell lines of T lymphocyte, B lymphocyte, and macrophage lineage, plus populations of elicited peritoneal exudate cells, thymocytes, and astrocytes coexpressed mRNA for both isoforms. The full length cDNA of the shorter alternate splice product, termed CXCR-4B, was cloned from peritoneal exudate cell RNA. Chinese hamster ovary cells transfected with either isoform, CXCR-4A or CXCR-4B, responded to stromal cell-derived factor-1alpha with a rise in intracellular calcium. Both alternate splice products are therefore functional stromal cell-derived factor-1 alpha receptors.
Human glomerular mesangial cell phagocytosis of apoptotic neutrophils: mediation by a novel CD36-independent vitronectin receptor/thrombospondin recognition mechanism that is uncoupled from chemokine secretion.
Authors: Hughes J , Liu Y , Van Damme J , Savill J 
Published: December 2022

Abstract
In this study we examined the mechanisms by which glomerular mesangial cells ingest apoptotic cells and the mesangial cell response to this event, since there is in vivo evidence that such semiprofessional phagocytes participate in phagocytic clearance of both apoptotic leukocytes and apoptotic resident cells from inflamed glomeruli, thereby promoting resolution of glomerulonephritis. Mesangial cell phagocytosis of apoptotic neutrophils in vitro was not affected by inhibitors of lectin-like receptors, phosphatidylserine receptors, the 61D3 Ag, and beta1 and beta2 integrins, receptors which have been implicated in phagocytosis of apoptotic cells by particular populations of semiprofessional and professional phagocytes. However, the specific inhibitory effects of cationic aminosugars, Arg-Gly-Asp-Ser (RGDS) peptide, and mAbs to phagocyte alpha(v)beta3 vitronectin receptor integrin and "bridging" thrombospondin 1 (TSP1) indicated that mesangial cell phagocytosis of apoptotic cells involved an alpha(v)beta3/TSP mechanism akin to that described for human monocyte-derived macrophages (Mphi) in which Mphi CD36 plays an important role in binding "bridging" TSP1. However, mesangial cells did not express CD36 and there was no evidence for involvement of alternative phagocyte receptors for TSP1, heparan sulfate proteoglycan and sulfatides. Nevertheless, phagocytosis of apoptotic neutrophils by either mesangial cells or Mphi failed to elicit secretion of IL-8 and MCP-1, representatives of each major class of proinflammatory chemotactic cytokines. We conclude that mesangial cell phagocytosis of apoptotic neutrophils involves a novel CD36-independent, alpha(v)beta3/TSP-mediated mechanism that is uncoupled from chemokine secretion, emphasizing the injury-limiting potential of mesangial cell phagocytosis of apoptotic cells.
Outside-in signaling by lipopolysaccharide through a tailless integrin.
Authors: Ingalls R R , Arnaout M A , Golenbock D T 
Published: December 2022

Abstract
Ligand binding to integrins activates intracellular signaling pathways that coordinate and regulate a variety of cellular responses. There is evidence to suggest that the cytoplasmic tails play a key role in several of these signaling events. We sought to determine whether the beta2 integrin complement receptor type 3 (CR3; CD11b/CD18), a receptor for LPS, could initiate an intracellular signal in the absence of its cytoplasmic domains. Expression of full length CR3 in a Chinese hamster ovary-K1 fibroblast line enabled serum-independent translocation of nuclear factor-kappaB in response to binding LPS. Unexpectedly, a cell line expressing a mutated form of CR3 deficient in the cytoplasmic domains was also competent for transmitting a signal in response to LPS. In contrast, phagocytosis of whole Gram-negative bacteria and iC3b-coated erythrocytes took place only with a full length receptor. Thus, while full length CR3 is necessary for productive phagocytic signals, LPS activation does not require the cytoplasmic domains. CR3 may function to activate cells by presenting LPS to a downstream signal transducer.
Activated T helper 1 and T helper 2 cells differentially express the beta-2-adrenergic receptor: a mechanism for selective modulation of T helper 1 cell cytokine production.
Authors: Ramer-Quinn D S , Baker R A , Sanders V M 
Published: December 2022

Abstract
We recently reported that resting clones of murine Th1 cells, but not resting Th2 cells, expressed a detectable level of the beta-2-adrenergic receptor (beta 2AR). In the present study, we proposed that the level of beta 2AR expression on anti-CD3 mAb-activated CD4+ effector Th cells may differ from the level on resting cells, and that a change in receptor expression may alter the functional responsiveness of these cells to either the beta 2AR-selective ligand terbutaline or the sympathetic neurotransmitter norepinephrine. Following anti-CD3 activation, the beta 2AR was expressed on Th1 cells, but not Th2 cells. The number of binding sites on Th1 cells was maintained, with no change in affinity, over a 24-h activation period. When Th clones were exposed to terbutaline following anti-CD3 activation, Th1 cell, but not Th2 cell, cytokine production was modulated. IL-2 production by Th1 cells was decreased, while IFN-gamma production was not significantly altered. The decrease in IL-2 production was concentration dependent and was blocked by an antagonist. In comparison with control supernatants, the lower level of IL-2 present in terbutaline-exposed culture supernatants supported the proliferation of an IL-2-dependent Th1 clone to a lesser degree. Additionally, norepinephrine down-modulates IL-2, but not IFN-gamma, production by binding specifically to the beta-adrenergic receptor. Thus, a detectable level of the beta 2AR is expressed on activated Th1 cells, but not activated Th2 cells, thereby providing a mechanism by which IL-2 production is preferentially modulated by an endogenous and therapeutic ligand following Th1 cell activation.
Mercuric chloride-induced vasculitis in the Brown Norway rat: alpha beta T cell-dependent and -independent phases: role of the mast cell.
Authors: Kiely P D , Pecht I , Oliveira D B 
Published: December 2022

Abstract
Mercuric chloride induces a necrotizing vasculitis in the Brown Norway (BN) rat. This occurs in two phases, between 1 and 5 days (early) and between 12 and 20 days (late) after initiation of HgCl2. One outbred and four inbred rat strains were found to be susceptible to early vasculitis, but only the BN strain developed late vasculitis. In the BN strain, treatment with the mAb R73 (anti-alpha beta TCR) inhibited T cell function, completely prevented the late vasculitis, but had no effect against early vasculitis, indicating that early and late vasculitis is controlled by different genetic and cellular mechanisms. The role of the mast cell in the alpha beta T cell-independent early phase was studied. Serum concentrations of rat mast cell protease II rose following HgCl2 treatment, indicating mast cell degranulation. The reagents Doxantrazole and the mAb G63, which suppress mast cell secretory responses, also prevented the rise in rat mast cell protease II and significantly reduced the early vasculitis. The demonstration of an alpha beta T cell-dependent phase supports previous experimental data that T cells play an important role in the pathogenesis of vasculitis. The presence of an earlier alpha beta T cell-independent phase is a unique observation. The data support a role for the mast cell in the early vasculitis.
Inhibitory effects of chronic ethanol consumption on cellular immune responses to hepatitis C virus core protein are reversed by genetic immunizations augmented with cytokine-expressing plasmids.
Authors: Geissler M , Gesien A , Wands J R 
Published: December 2022

Abstract
Chronic hepatitis C viral (HCV) infection is a major clinical problem in alcoholics with liver disease and may result from ethanol effects on the host immune response. To experimentally assess such effects, the DNA-based immunization approach was used to produce humoral and cellular immune responses against the HCV core protein in mice. Mice were fed an ethanol or isocaloric pair-fed control liquid diet followed by immunizations with HCV core DNA-expressing constructs. Chronic ethanol feeding was found to inhibit Th cell and CTL activities and substantially reduced cytokine secretion as well. In addition, a switch from Th1 to Th0 subtype was observed in proliferating CD4+ T cells derived from chronic ethanol-fed mice. These immunosuppressive effects were directly due to ethanol since crossover experiments to an isocaloric control diet restored the defects in cellular immunity. Furthermore, we determined if coadministration of an IL-2 or GM-CSF DNA expression plasmid with a plasmid expressing the HCV core protein (pHCV2-2) would reverse the inhibitory effects of chronic ethanol feeding on cellular immune responses. Coimmunization of chronic ethanol-fed mice with either IL-2 or GM-CSF expression plasmids restored cellular immunity and induced CD4+ inflammatory T cell and CD8+ CTL responses comparable with control mice immunized with pHCV2-2 alone. These studies provide evidence of how chronic ethanol feeding may effect cellular immune responses to a viral structural protein in the context of genetic immunization.
oct-2 gene disruption eliminates the peritoneal B-1 lymphocyte lineage and attenuates B-2 cell maturation and function.
Authors: Humbert P O , Corcoran L M 
Published: December 2022

Abstract
Targeted mutation of the gene for the Oct-2 transcription factor in mice caused neonatal lethality and abrogated mitogen-induced proliferation and differentiation of mature B lymphocytes in vitro. Here we show that Oct-2 is required for normal humoral responses upon immunization with T cell-dependent as well as T-independent Ags. oct-2-null T cell behavior was normal, implying a B cell-restricted lesion. oct-2-/- B cells displayed aberrant behavior during activation in vitro: both acquisition of markers of cellular activation and cell survival were diminished. Production of early B lineage cells in the bone marrow was normal, yet mature B cells were under-represented in blood and lymphoid organs. Furthermore, peritoneal B-1 lymphocytes were not detected in animals with a reconstituted oct-2-/- lymphoid system. We conclude that Oct-2 is required for B-1 cell maintenance and for normal Ag-driven maturation of conventional B cells in vivo.
Cloning and analysis of the promoter region of CCR5, a coreceptor for HIV-1 entry.
Authors: Moriuchi H , Moriuchi M , Fauci A S 
Published: December 2022

Abstract
The chemokine receptor CCR5 is a cofactor for cellular entry of macrophage-tropic strains of HIV-1. Expression of CCR5 is restricted to T cells, macrophages, and certain cell lines; however, the mechanisms controlling its expression remain largely unknown. To delineate these mechanisms, approximately 1.0 kb of DNA from the immediate 5' upstream region of CCR5 was cloned and characterized. CCR5 promoter activity was up-regulated by PMA, and a region spanning -417 to +61 relative to the transcription start site was sufficient for the basal and induced activity. DNase I footprinting assays demonstrated several protected areas within this region, and gel shift assays determined binding sites for transcriptional factors Oct-1, Oct-2, T cell factor 1alpha, and GATA1. CCR5 promoter activity was also induced by IL-2 or anti-CD3 Ab, while stimulation with anti-CD28 Ab markedly reduced CD3-mediated up-regulation of the CCR5 promoter. Flow cytometry confirmed the findings at the level of cell surface expression. Further delineation of the regulation of the CCR5 promoter will be important for a more comprehensive understanding of the pathogenesis of HIV disease.