bluuebunny/crossref_metadata_2025_split huggingface dataset:
Expression of two structurally identical viral superantigens results in thymic elimination at distinct developmental stages.
Authors: Morishima C , Norby-Slycord C , McConnell K R , Finch R J , Nelson A J , Farr A G , Pullen A M 
Published: January 2023

Abstract
Mouse mammary tumor virus proviral integrants encode superantigens. Developing thymocytes bearing TCRs with particular V beta elements encounter these endogenous viral superantigens as self molecules in the thymus and are consequently clonally eliminated. To study this mechanism of tolerance induction, we have bred B10.BR-Mtv-1 and B10.BR-Mtv-6 mice, which carry either Mtv-1 or Mtv-6 proviruses but are otherwise genetically identical. The protein products of these mouse mammary tumor virus integrants, vSAG1 and vSAG6, both interact with V beta 3+ T cells and have identical amino acid sequences. Interestingly, vSAG6 expression results in the complete deletion of V beta 3+ peripheral T cells, whereas vSAG1 expression results in only partial deletion. Flow cytometric analyses indicate that B10.BR-Mtv-6 mice delete V beta 3+ thymocytes at the immature CD4+8+ stage, whereas B10.BR-Mtv-1 mice delete only mature CD4+ or CD8+ cells. In addition, the two strains exhibit different time courses of thymic deletion: neonatal B10.BR-Mtv-6 mice eliminate V beta 3+ T cells by day 2, in contrast to B10.BR-Mtv-1 mice in which deletion does not occur until day 15. RNase protection assays demonstrate that B10.BR-Mtv-6 mice have significantly greater thymic vSAG6 mRNA expression levels than vSAG1 levels in B10.BR-Mtv-1 animals, correlating with a more complete deletion of reactive thymocytes at an earlier point in the maturational sequence.
A protective "concealed" antigen from Boophilus microplus. Purification, localization, and possible function.
Authors: Riding G A , Jarmey J , McKenna R V , Pearson R , Cobon G S , Willadsen P 
Published: January 2023

Abstract
A membrane protein that can be used successfully to vaccinate cattle against the tick Boophilus microplus has been purified and characterized. The mature protein, which is referred to as Bm91, has an apparent m.w. of 86,000, an isoelectric point of 4.8 to 5.2, and is glycosylated, with an affinity for lentil lectin. Bm91 is of relatively low abundance, with approximately 300 to 400 micrograms being recovered from 1 kg of semiengorged adult female ticks. The protein is located largely in the salivary gland and gut of these ticks. Partial amino acid sequence data for the protein show striking similarities to that of mammalian angiotensin-converting enzyme, suggesting that the Ag may have an enzymatic function. The protein seems not to be recognized by sera from cattle with extensive exposure to ticks under natural conditions. The immunity induced by vaccination, therefore, represents another example of vaccination against a hematophagous parasite with "concealed" Ags.
Regulation of T helper cell responses in experimental murine schistosomiasis by IL-10. Effect on expression of B7 and B7-2 costimulatory molecules by macrophages.
Authors: Flores Villanueva P O , Reiser H , Stadecker M J 
Published: January 2023

Abstract
Granulomatous inflammation in schistosomiasis is a manifestation of cell-mediated hypersensitivity to parasite egg Ags that is predictably reduced in size over the course of the disease. This down-regulation may reflect a state of anergy in the T cells mediating granuloma formation after interaction with accessory cells incapable of providing full stimulation. The present studies were conducted to investigate this mechanism at the molecular level. We found that granuloma macrophages (GM) strongly inhibit the ability of splenic APC to stimulate egg Ag-specific Th1 responses. This property was shown to be dependent on their secretion of IL-10. Moreover, activated GM in culture were found to express little or no costimulatory Ags B7 or B7-2. However, when their autocrine secretion of IL-10 was neutralized with specific mAb, GM displayed an up-regulation of costimulatory molecules as well as of MHC class II Ags. Most importantly, GM cultured in the presence of anti-IL-10 mAb, acquired the ability to stimulate egg Ag-specific T cells. By independently blocking each of the induced costimulatory Ags, it appeared that B7-2 molecules provided stronger costimulation than B7. In separate experiments, culture supernatants from GM exerted a powerful inhibition of costimulatory Ag expression on Con-A-stimulated peritoneal exudate cells in vivo, which could similarly be attributed to IL-10. Our results demonstrate that IL-10 can play a critical role in the generation of accessory cells that, by virtue of down-regulation of costimulatory molecules, may be capable of inducing anergy in T cells mediating the vigorous granulomatous response of acute stage schistosomiasis. Our studies lend support to the contention that a state of unresponsiveness in pathogenic T cells may precipitate the down-regulation of granuloma formation and provide a molecular basis for the underlying mechanisms.
Local production of IFN-gamma abrogates the intraocular immune privilege in transgenic mice and prevents the induction of ACAID.
Authors: Geiger K , Sarvetnick N 
Published: January 2023

Abstract
The eye represents an immunologically privileged site with specific properties mediated by immunosuppressive constituents of the intraocular fluids. This system, termed ACAID (anterior chamber-associated immune deviation), was originally attributed to the anterior chamber of the eye, and is characterized by impairment of the cellular immune response, including a lack of delayed type hypersensitivity (DTH) reaction in response to intraocularly presented Ag and decreased cytotoxicity of T cells. We created a transgenic mouse with ectopic expression of IFN-gamma in the photoreceptors of the retina to study the effects of this cytokine on the immunosuppressive properties of the eye with special regard to the posterior chamber. BALB/c-derived transgenic and nontransgenic mice were challenged intravitreally either with allogeneic splenocytes from C57Bl/6 mice or with BSA, in IFA, and tested for the delayed type hypersensitivity reaction to BSA by intrapinnal injection of the same Ag in the ear 7 days later. Pathologic changes of the eyes were evaluated by histology and immunohistochemistry. We found that transgenic mice developed an increased amount of ocular inflammation in response to both Ags compared with the nontransgenic controls. Furthermore, transgenic mice showed a marked DTH reaction to BSA, whereas nontransgenic mice did not. Our results indicate that local IFN-gamma production disturbs the immunosuppressive properties of the eye and prevents the induction of ACAID in response to intraocularly presented Ag. The data confirm the extension of the intraocular immune privilege to the posterior chamber of the eye.
CTL access to tissue antigen is restricted in vivo.
Authors: Ando K , Guidotti L G , Cerny A , Ishikawa T , Chisari F V 
Published: January 2023

Abstract
MHC class I-restricted, hepatitis B surface Ag (HBsAg)-specific, CD8+ polyclonal CTL lines and clones cause a severe necroinflammatory liver disease when they are injected i.v. into transgenic mice that display widespread tissue expression of HBsAg. Surprisingly, the same CTLs fail to cause disease in any other HBsAg-positive tissue in these animals. However, the CTLs are highly cytopathic for HBsAg-positive renal tubules and choroid plexus epithelial cells when they are injected extravascularly, either beneath the kidney capsule or intracerebrally. Analysis of the microvascular anatomy of these tissues reveals that the hepatic sinusoid is characterized by a discontinuous endothelium and the absence of a basement membrane. In contrast, the vasculature of most other tissues displays a continuous endothelium and basement membrane; and the epithelial cells of many of these tissues are also surrounded by a separate basement membrane. These results suggest that viral, tumor, and normal self Ags expressed in the liver are readily accessible to class I-restricted T cells, whereas the vascular endothelium and/or the vascular and cellular basement membranes constitute an extremely effective barrier that precludes CTL access to tissue Ag at many other sites. Because class I-restricted Ag recognition occurs throughout the body in many natural diseases and disease models, the vascular barrier must be breached by other events before CTL access to endogenously synthesized epithelial Ag can occur.
T cell-dependent, B cell-activating properties of antibody-coated small latex beads. A new model for B cell activation.
Authors: Luxembourg A T , Cooper N R 
Published: January 2023

Abstract
We have developed a new model to study B cell activation induced by complex particulate Ag, immune complexes, and viruses. As the surrogate for such Ag, we have used 100-nm fluorescent latex beads bearing mAb to IgM and IgD. Anti-IgM- and anti-IgD-coated small latex beads bind readily to tonsil resting B cells and induce homotypic B cell aggregation. Aggregation induced by anti-IgM-coated beads but not by anti-IgD-coated beads was massively enhanced by IL-2 and IL-4. Anti-IgM- and anti-IgD-coated beads increased (4- to 12-fold) c-fos and c-myc mRNA levels in resting B cells in a dose-dependent manner; this increase was tyrosine kinase dependent. Anti-IgM- and anti-IgD-coated beads were mitogenic for resting B cells, but unlike other B cell activation models, mitogenesis was absolutely dependent on the presence of IL-2 or IL-4. Finally, anti-IgM-coated beads but not anti-IgD-coated beads were internalized as single beads into small, thin-walled endocytic vesicles; internalization was absolutely dependent on the presence of IL-4. Binding and internalization can be readily quantified because the beads are fluorescent. This model can also be used to study the functions of other cell surface molecules that modulate Ag-specific B cell immune responses. It will also be used for examining multiple aspects of T-B cell interactions during immune responses and Ag processing because of the dependence on T cell factors for B cell activation, coupled with the finding that the Ab-coated beads are internalized.
B cell antigen receptor cross-linking induces phosphorylation of the p21ras oncoprotein activators SHC and mSOS1 as well as assembly of complexes containing SHC, GRB-2, mSOS1, and a 145-kDa tyrosine-phosphorylated protein.
Authors: Saxton T M , van Oostveen I , Bowtell D , Aebersold R , Gold M R 
Published: January 2023

Abstract
Ligation of the B cell AgR activates p21ras (Ras). We have investigated the effects of AgR ligation on three proteins that have been implicated as regulators of Ras: SHC, GRB-2, and mSOS1. We show that AgR cross-linking in B cells stimulated tyrosine and serine phosphorylation of SHC. This correlated with the formation of complexes containing SHC, GRB-2, mSOS1, and an unidentified 145-kDa tyrosine-phosphorylated protein. These complexes were present in the cytosol, as well as in the membrane fraction of the cells, where Ras is located. By using a GRB-2 fusion protein to probe blots, we showed that SHC was the major protein that GRB-2 bound to in anti-Ig-stimulated B cells. This argues that SHC couples GRB-2/mSOS1 to the 145-kDa protein and that SHC is likely to be essential for mSOS1 function in B cells. Finally, we found that AgR cross-linking stimulated phosphorylation of mSOS1 and that this could be blocked by an inhibitor of protein kinase C. Thus, signaling by the B cell AgR stimulates phosphorylation of SHC and mSOS1 and induces the formation of membrane-associated complexes containing SHC, GRB-2, mSOS1, and a 145-kDa protein. These events may be important for activation of Ras by the AgR.
V beta repertoire of murine hepatic T cells. Implication for selection of double negative alpha beta + T cells.
Authors: Seki S , Kono D H , Balderas R S , Theofilopoulos A N 
Published: January 2023

Abstract
To further define the origin, selection, and diversity of hepatic T cells, we have determined V beta gene expression profiles in double negative (DN, CD4-8-) and single positive (SP, CD4+8- or CD8+4-) alpha beta + liver T cells of DBA/2 mice. These I-E+ mice express mouse mammary tumor (Mtv) provirus-encoded endogenous superantigens of the Mlsa,c type, and thus display deletions/depletions of several V beta-bearing SP cells. Total liver alpha beta + T cells of these mice exhibited an overall V beta expression profile similar to splenic T cells, with the notable exception of high V beta 7 and V beta 8.1 expression. As previously reported, DN alpha beta + T cells were enriched highly in the liver. This subset exhibited a V beta expression profile similar to thymic DN alpha beta + cells with deletions/depletions in several V beta s, but high V beta 7 expression in both populations. Surprisingly, hepatic CD4+ cells also displayed high V beta 7 expression compared with splenic T cells, suggesting that hepatic DN alpha beta + and CD4+ T cells are selected via a common pathway. The V beta 7-expressing DN alpha beta + and CD4+ liver T cell populations were polyclonal, as evidenced by cloning and sequencing. High V beta 7 expression in these cells was undiminished with age. On the basis of V beta repertoire and surface phenotype, DN alpha beta + and/or certain CD4+ T cells seem to constitute a distinct population primarily found in the liver, thymus, and bone marrow. These cells may originate from SP T cells that have down-regulated their accessory molecules under certain activation conditions and, because of the accompanying expression of particular adhesion molecules, they accumulate in tissues such as the liver and thymus.
Inhibition of IFN-gamma activity in supernatants from stimulated human intestinal mononuclear cells prevents up-regulation of the polymeric Ig receptor in an intestinal epithelial cell line.
Authors: Youngman K R , Fiocchi C , Kaetzel C S 
Published: January 2023

Abstract
The polymeric IgR (pIgR) mediates transcytosis of polymeric IgA across mucosal epithelia. Expression of this receptor in HT-29.74 human colon carcinoma cells is up-regulated by the recombinant cytokines IFN-gamma, TNF-alpha, and IL-4. Here, we demonstrate that activation of freshly isolated human intestinal lamina propria mononuclear cells (LPMC) induces production of natural cytokines, and these act synergistically as potent stimulators of pIgR expression in HT-29.74 cells. LPMC from normal colonic mucosa were stimulated with PMA and calcium ionophore A-23187. The resulting supernatants consistently induced dose-dependent increases in pIgR expression by HT-29.74 cells, up to 65-fold. Analysis of four separate LPMC supernatants revealed mean concentrations of 8260 pg/ml for IFN-gamma, 420 pg/ml for TNF-alpha, and 15 pg/ml for IL-4. Ab-mediated neutralization of these cytokines suggested that the central regulator of pIgR expression in these supernatants was IFN-gamma. IL-4 neutralization had no effect on induction and TNF-alpha neutralization slightly reduced induction. In contrast, IFN-gamma neutralization abolished up to 93% of pIgR induction and had essentially the same effect as simultaneous neutralization of all three cytokines. In conclusion, our data demonstrate that natural cytokines, predominantly IFN-gamma, produced by stimulated human intestinal lymphocytes and macrophages have the capacity to up-regulate dramatically pIgR expression in an intestinal epithelial cell line, strongly suggesting that their action in vivo leads to enhancement of local defense functions mediated by IgA.
Epitope and functional specificity of peripheral tolerance induction in experimental autoimmune encephalomyelitis in adult Lewis rats.
Authors: Malotky M K , Pope L , Miller S D 
Published: January 2023

Abstract
Intravenous treatment of Lewis rats with neuroantigen-coupled splenocytes 7 days before the induction of experimental autoimmune encephalomyelitis with guinea pig myelin basic protein (GP-MBP) resulted in a significant reduction of both the incidence and severity of clinical disease. To test the epitope and functional specificities of the unresponsiveness, splenocytes (SP) coupled with the major encephalitogenic MBP determinant, GP-68-86, were compared with those coupled with intact GP-MBP for the ability to down-regulate clinical disease and Ag-specific T cell responses (proliferation, cytokine production, and delayed-type hypersensitivity) in animals primed with either intact GP-MBP/CFA or GP-68-86/CFA. GP-MBP-SP and GP-68-86-SP were equally efficient at significantly inhibiting clinical disease in animals primed with GP-68-86/CFA. In contrast, tolerization with intact GP-MBP-SP was significantly more efficient than that with GP-68-86-SP at reducing disease incidence and severity in GP-MBP/CFA-primed animals, which indicates a role for secondary (cryptic) encephalitogenic epitopes in GP-MBP-induced disease. By testing a panel of GP-68-86 peptides that contained conservative amino acid substitutions at either position 75 (A75) or 80 (P80) or at both, residues that previously had been shown to be TCR contact residues, for their ability to inhibit experimental autoimmune encephalomyelitis induction, were assessed for the fine specificity of tolerance induction. None of the substituted peptides were capable of affecting the course of paralytic disease that had been induced by sensitization with the native GP-68-86 epitope, but all significantly reduced a milder form of the disease that had been produced by priming with the (A75,P80) 68-86 substituted peptide. With regard to the functional specificity of tolerance induction, lymph node T cells derived from either GP-MBP-SP- or GP-68-86-SP-treated animals exhibited a marked reduction in both proliferation and production of Th1-derived cytokines (IL-2, IFN-gamma, and lymphotoxin/TNF-alpha) in response to either GP-MBP or GP-68-86 in culture. In contrast, no consistent significant differences in delayed-type hypersensitivity responses were observed in any of the experimental groups relative to controls. Histologic examination of central nervous system tissues from the tolerant and control groups revealed significantly reduced, but still demonstrable, levels of perivascular infiltration even in asymptomatic animals.
Inhibition of activation-induced programmed cell death and restoration of defective immune responses of HIV+ donors by cysteine protease inhibitors.
Authors: Sarin A , Clerici M , Blatt S P , Hendrix C W , Shearer G M , Henkart P A 
Published: January 2023

Abstract
In vitro activation of PBLs from HIV+ individuals resulted in programmed cell death (PCD) within 2 days in 58 of 95 HIV+ blood donors, in contrast to only two of 30 control HIV- donors. CD4+ and CD8+ T cells from HIV+ donors died under these conditions, and these cells showed apoptotic nuclear morphology and DNA fragmentation. To test the hypothesis that this cell death shares a common biochemical pathway with that induced by TCR cross-linking in normal dividing T cells, inhibitors of the calcium-activated cysteine protease calpain were tested for their ability to block the activation-induced PCD of HIV+ donors. The E-64 (epoxysuccinyl) class of cysteine protease inhibitors gave 40% to 60% inhibition of HIV+ PCD responses, while the aldehyde inhibitors, leupeptin and calpain inhibitor II, gave 60% to 67% inhibition. The involvement of this calpain-dependent death pathway in HIV-induced functional T helper cell deficiency was tested by examining the effect of calpain inhibitors on the defective Ag- and mitogen-dependent proliferative responses of HIV+ donors. Twenty to fifty percent of such defective responses were significantly restored toward normal levels by calpain inhibitors, whereas control responses by normal donors were largely unaffected. These data suggest that a calpain-dependent PCD pathway contributes to HIV-associated immunodeficiency and suggest the use of calpain inhibitors as a possible route to therapy of HIV infection.
Expansion of selected V delta 1+ gamma delta T cells in systemic sclerosis patients.
Authors: Yurovsky V V , Sutton P A , Schulze D H , Wigley F M , Wise R A , Howard R F , White B 
Published: January 2023

Abstract
We have previously shown an increased percentage of gamma delta T cells expressing the TCR V delta 1 gene segment in the peripheral blood and bronchoalveolar lavage fluid of patients with systemic sclerosis (SSC). To estimate clonality of these V delta 1+ T cells, the diversity of V delta 1 junctional regions (V-D-J) was examined using a reverse transcriptase-PCR to amplify TCR delta-chain transcripts isolated from PBMC, lung, esophagus, stomach, or skin of patients and controls. Limited diversity of V delta 1-J delta junctional regions in SSC patients was demonstrated by comparing the size distribution of PCR-amplified junctional region cDNA from patients with that of controls. Sequence analyses confirmed that V delta 1-J delta junctional regions from the blood of SSc patients had less diversity than those from controls, in that a significantly higher proportion of sequences were repeated in patients (54.4 vs 19.4% in controls). Evidence for selection of the V delta 1+ T cells in the tissues of SSC patients came from the findings that the same V delta 1-J delta junctional sequences persisted in an individual patient over time and that identical junctional sequences were isolated from multiple sites. Analysis of deduced amino acid sequences revealed two clusters of similarities among the junctional regions from patients. These data suggest that expansion of V delta 1+ gamma delta T cells may be Ag driven in SSC patients.
The in vivo and in vitro effects of antibodies against rabbit beta 2-integrins.
Authors: Rutter J , James T J , Howat D , Shock A , Andrew D , De Baetselier P , Blackford J , Wilkinson J M , Higgs G , Hughes B 
Published: January 2023

Abstract
Beta 2-integrins play a crucial role in the development of an inflammatory response. In ours study, Abs have been used to investigate the role of individual members of this family of adhesion molecules in both in vivo and in vitro assays. An Ab against rabbit LFA-1 effectively inhibited the adhesion of rabbit polymorphonuclear leukocytes to rabbit endothelial cells in culture and was also effective in blocking cell recruitment to the peritoneum and vascular leakage at dermal sites of inflammation. An Ab that inhibited rabbit complement receptor type 3 function in vitro failed to inhibit cell recruitment to the peritoneum or vascular leakage in response to intradermal FMLP. Histologic studies suggested that the anti-complement receptor type 3 Ab may have modified the cell migration process.