bluuebunny/crossref_metadata_2025_split huggingface dataset:
Autoantigenic epitopes on hY5 Ro RNA are distinct from regions bound by the 60-kDa Ro and La proteins.
Authors: Granger D , Tremblay A , Boulanger C , Chabot B , Ménard H A , Boire G 
Published: December 2022

Abstract
We recently reported the identification in human anti-Ro serum of Abs specifically immunoprecipitating deproteinized hY5 RNA. In the present report, we characterized the epitopes recognized by anti-hY5 RNA Abs. Using deletion and site-directed mutagenesis of hY5 cDNA and in vitro transcribed RNAs with intact and 3'-shortened ends, we have defined two conformational antigenic determinants distinct from the regions known to bind Ro and La proteins. One of these epitopes (epitope A) is present in the middle portion of hY5 RNA and is dependent on the presence of a four-nucleotide sequence (AACC at position 58-61) that may form a single-stranded loop. Deleting these four nucleotides or modifying the stem structures proximal or distal to this loop abolishes recognition of the mutated RNAs by Abs. The second epitope (epitope B) requires the presence of another four-nucleotide sequence (CUUG at position 74-77) in between the Ro and La binding sites. Deleting this CUUG sequence or modifying nucleotides on the 5' side of the stem structure below the Ro60 binding site severely compromises the interaction with Abs. Since Abs to deproteinized hY RNAs are restricted to anti-hY5 RNA and target determinants not involved in interactions with known hY5 RNA-binding proteins, human RohY5 particles may play a direct role in the immunization process, leading to the production of anti-hY5 RNA autoantibodies.
A model for induction of T cell-independent humoral immunity in response to polysaccharide antigens.
Authors: Snapper C M , Mond J J 
Published: December 2022

Abstract
We provide a model for induction of T cell-independent, polysaccharide-specific Ig secretion in response to bacterial challenge. Two predominant pathways are defined that require the concerted action of multivalent membrane Ig cross-linking by the polysaccharide Ag with 1) various B cell-activating moieties contained within the bacterial pathogen and/or 2) cytokines, such as IFN-gamma and granulocyte-macrophage colony-stimulating factor produced by NK cells and macrophages, that become activated in a T cell-independent manner during bacterial infection.
Regulation of CTL recognition by receptors for HLA-DR molecules.
Authors: Nakajima H , Takiguchi M 
Published: December 2022

Abstract
NK cells and some T cells have receptors for MHC class I molecules that negatively regulate the recognition of these cells. In the present study, we show alpha beta CTL clones carrying the receptors for HLA-DR molecules that inhibit this cytotoxicity. The cytotoxicity of two CTL clones possessing NK activity was inhibited by the surface expression of HLA-DR and HLA class I molecules on the target cells. The inhibitory effect of DR molecules on the cytotoxicity of the CTL clones was confirmed by using T2 transfectants expressing HLA-DR3. These results suggest that receptors for both HLA-DR and HLA class I molecules negatively regulate the recognition of T cells.
Effect of HLA-DM transfection on hen egg lysozyme presentation by T2.Ak cells.
Authors: Albert L J , Ghumman B , Watts T H 
Published: December 2022

Abstract
T2 cells have a large homozygous deletion in the MHC II region. Transfection of MHC class II genes into T2 cells allows presentation of peptide but not native protein Ags. This defect in protein presentation has been attributed to the lack of HLA-DM, an MHC class II-related protein that facilitates the release of an invariant chain peptide (CLIP) intermediate from nascent MHC class II proteins within the endocytic compartment of APC. Here, we show that Ak molecules within isolated late endosome fractions of T1.Ak (wild-type) vs T2.Ak (HLA-DM-deficient) bind biotin-HEL46-61 at comparable levels, consistent with previous observations that Ak molecules on T2 cells are not predominantly occupied with CLIP. However, Ak molecules in the late endosomes of T2.Ak fail to present peptide to a T hybrid, whereas the late endosomes from T1.Ak have no such defect. Transfection of HLA-DM A and B into T2.Ak partially restores protein Ag presentation by T2.Ak cells. These data suggest that HLA-DM can play a role in Ag presentation in addition to its role in CLIP release. However, even after DM transfection there remains a 10-fold difference in the dose-response curve for hen egg lysozyme presentation by T1.Ak vs T2.Ak/DM cells. In addition, HLA-DM transfection fails to restore presentation by late endosome fractions. The failure to fully restore Ag presentation in T2.Ak cells by DM transfection suggests that another gene product, required for efficient Ag presentation, may be absent from the late endosomes of T2.
TCR recognition of the Hb(64-76)/I-Ek determinant: single conservative amino acid changes in the complementarity-determining region 3 dramatically alter antigen fine specificity.
Authors: Hsu B L , Donermeyer D L , Allen P M 
Published: December 2022

Abstract
To identify the structural basis of Ag fine specificity, TCR sequences from a panel of Hb(64-76)/I-Ek-specific T cells were compared and found to be restricted in variable (V) gene usage, predominantly using BV1 or BV15 and AV4 or AV10 genes. TCRA and TCRB junctional sequences were extremely diverse. No conservation of length or position was found, which distinguishes this response from others, but correlates with the range of fine specificities that these T cells display. A remarkable subtlety in the recognition of Hb(64-76) was revealed from the study of the response to the D73 variant of Hb(64-76), which contains a conservative change in an MHC anchor residue not affecting the binding affinity to I-Ek. To one group of T cells this determinant was non-cross-reacting with Hb(64-76), whereas another recognized both Ags. Interesting, they all used a different constellation of TCRBV genes than that found in Hb(64-76) recognition. To limit the variability in the anti-Hb(64-76) TCR repertoire, transgenic mice expressing a fixed TCRB rearrangement from a Hb(64-76)-specific T cell were used. In Hb(64-76)-specific TCR from these mice, the endogenous alpha-chains pairing with the transgenic beta-chain were highly restricted in their AV gene usage. A comparison of two pairs of closely related T cells of these endogenous TCR variants, one differing by a single, conservative substitution in the complementarity-determining region 3 and the other containing a positional switch of two amino acids, revealed dramatically different fine specificities. Overall, these findings highlight the exquisite sensitivity of the TCR- peptide/MHC interaction to subtle alterations in any of the components.
Species-dependent post-translational modification and position 2 allelism: effects on streptococcal superantigen SSA structure and V beta specificity.
Authors: Stevens K R , Van M , Lamphear J G , Orkiszewski R S , Ballard K D , Cook R G , Rich R R 
Published: December 2022

Abstract
Epidemiologic and molecular population genetic analyses support a role for superantigens (SAg) in the pathogenesis of severe staphylococcal and streptococcal infections. To investigate how variations in SAg structure influence immunomodulatory activity, we examined the biochemical and functional properties of two allelic variants of streptococcal SAg SSA that differ at position 2. Mass spectrometry revealed both recombinant (Escherichia coli) and native (Streptococcus pyogenes) SSA allelic variants to have significantly larger molecular masses than predicted by primary sequence alone and provided evidence that the proteins were modified by the addition of biochemical moieties, a phenomenon that has not been described for related SAg. Furthermore, the molecular masses of native and recombinant SSA were not the same; SSA was differentially post-translationally modified by the two bacterial genera. The substitution of E. coli-dependent processing for that of S. pyogenes altered both protease digestion and V beta specificity, suggesting that recombinant SAg from E. coli may not accurately represent the native toxin. In addition, the observation that SSA allelic variants differed in V beta specificity supports a role for position 2 in SSA-TCR interactions. That SSA position 2 contributes to V beta specificity could not have been predicted from functional or crystallographic studies of other SAg and suggests that SSA may adopt unique interactions with TCR and/or MHC class II molecules. Determining the structural basis for these differences should offer additional clues to the manner in which SAg exert their effects on the immune system during infection and may allow the designing of SAg mutants with specific quantitative and qualitative immunomodulatory properties.
Bacteria in the bloodstream are trapped in the liver and killed by immigrating neutrophils.
Authors: Gregory S H , Sagnimeni A J , Wing E J 
Published: December 2022

Abstract
The critical role of the liver in the resolution of systemic bacterial infections is well documented. In the case of Listeria monocytogenes, approximately 60% of bacteria inoculated i.v. into mice are recovered in the liver at 10 min after infection. Here we report that the Listeria recovered at 10 min were distributed equally among the hepatocyte and nonparenchymal liver cell populations. The majority (&gt;/= 75%) of these organisms were bound extracellularly as judged by their sensitivity to gentamicin. In contrast, &gt;/= 93% of Listeria recovered in the liver at 6 h were located within hepatocytes. The listerial burden of the liver decreased 0.5 to 1.0 log, between 10 min and 6 h after infection. This decrease correlated with a sevenfold increase in the percentage of neutrophils that constituted the nonparenchymal cell population. Mice rendered neutrophil deficient by pretreatment with anti-granulocyte (RB6-8C5) mAb exhibited a significant increase (&gt;300%) rather than a decrease in liver Listeria and a marked increase in hepatocyte damage. Similarly, neutrophil-deficient mice exhibited a reduced capacity to eliminate Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus that were cleared by the liver and bound extracellularly to hepatocytes and nonparenchymal cells. These findings document the crucial role of immigrating neutrophils in nonspecific host defenses to systemic bacterial infections expressed within the liver.
L-selectin (CD62L) blockade does not impair peritoneal neutrophil emigration or subcutaneous host defense to bacteria in rabbits.
Authors: Sharar S R , Chapman N N , Flaherty L C , Harlan J M , Tedder T F , Winn R K 
Published: December 2022

Abstract
Neutrophil (PMN) recruitment into systemic inflammatory sites in vivo is thought to be initiated by selectin-mediated endothelial adherence. We explored the role of L-selectin (CD62L) in leukocyte emigration following instillation of bacteria into the peritoneum or s.c. skin in rabbits. Pretreatment with blocking mAb against L-selectin (LAM1.3) reduced peritoneal PMN emigration 4 h after i.p. inoculation with 10(10) CFU of Escherichia coli by only 17% compared with animals receiving a nonblocking L-selectin mAb (LAM1.14). Peritoneal PMNs from saline-treated rabbits demonstrated a complete absence of L-selectin, whereas those from LAM1.3-treated animals retained 43% of their baseline L-selectin expression. This suggests that L-selectin shedding is not a requisite event for PMN emigration under these conditions. In rabbits given s.c. inoculations with either Staphylococcus aureus or E coli, pretreatment with mAb LAM1.3 did not significantly impair PMN emigration at 24 h, nor increase the incidence, size, or associated mortality of resulting abscesses at 7 days compared with animals receiving nonblocking mAb LAM1.14. We conclude that: 1) mAb blockade of L-selectin in vivo only modestly affects acute, E. coli-induced peritoneal PMN emigration; and 2) L-selectin blockade does not increase infectious sequelae associated with s.c. bacterial inoculation. These findings of only mildly reduced PMN emigration into the peritoneum and no alteration in s.c. host defense differ from those reported with L-selectin blockade under other, nonbacterial inflammatory conditions, and suggest that redundant selectin-mediated mechanisms (P- and E-selectin) are sufficient for normal PMN emigration in response to bacterial stimulation.
I-309/T cell activation gene-3 chemokine protects murine T cell lymphomas against dexamethasone-induced apoptosis.
Authors: Van Snick J , Houssiau F , Proost P , Van Damme J , Renauld J C 
Published: December 2022

Abstract
We have previously reported that cytokines such as IL-9, IL-4, and IL-6 protect murine thymic lymphoma cell lines against dexamethasone-induced apoptosis. A similar activity, which could not be ascribed to any of these factors, was found in a number of human T cell supernatants that enabled mouse BW5147 thymic lymphoma not only to escape apoptosis but also to maintain proliferation. The protein responsible for this activity was purified to homogeneity from the culture medium of activated leukemic T cells and was found to be identical with the I-309 chemokine. Half-maximal anti-apoptotic activity was obtained with approximately 1 ng/ml, a concentration considerably lower than that required for the monocyte chemotactic activity of this molecule, as measured on THP-1 cells. The purified I-309 also improved the survival of two other mouse thymic lymphoma cell lines. This activity was as potent as that of IL-9, which was the strongest anti-apoptotic factor found to date for these cells. Similar results were obtained for BW5147 cells with recombinant I-309 and with T cell activation gene-3, the murine homologue of I-309, but not with other members of the chemokine family, including IL-8, neutrophil-activating peptide-2, granulocyte chemotactic protein-2, macrophage inflammatory protein-1a, RANTES (regulated upon activation, normal T cell expressed and secreted), monocyte chemotactic protein-1 (MCP-1), and MCP-2. MCP-3, however, showed a minor, but significant effect in this model. Unlike that of IL-9, the activity of I-309 was completely inhibited in the presence of pertussis toxin, indicating the involvement of a G protein in this process.
The baboon erythrocyte complement receptor is a glycophosphatidylinositol-linked protein encoded by a homologue of the human CR1-like genetic element.
Authors: Birmingham D J , Logar C M , Shen X P , Chen W 
Published: December 2022

Abstract
The human erythrocyte CA receptor (E-CR) is the type 1 complement receptor (CR1), the most common form of which is a 220,000 Mr integral membrane glycoprotein composed of 30 short consensus repeats (SCRs). The E-CR of many nonhuman primates is a smaller receptor of unknown genetic origin. Recently, we identified a chimp cDNA, termed CR1b, which represented transcription of a homologue of the human genetic element, CR1-like. The purpose of this study was to identify CR1b in the baboon and, if present, determine whether it encodes the 65,000 Mr baboon E-CR. Baboon bone marrow cDNA was amplified by PCR using primers specific for the signal peptide-encoding region of human CR1 and the 3' region of chimp CR1b. This amplification yielded a CR1b sequence predicted to encode seven SCRs followed by a hydrophobic region, with an N terminus homologous to the N terminus of baboon E-CR. Expression of baboon CR1b yielded a membrane protein that reacted with an anti-CR1 mAb, was identical in size to baboon E-CR, and, like baboon E-CR, could bind baboon C3 linked to activated thiol-Sepharose (C3i-ATS), but not human C3i-ATS. Phosphatidylinositol-specific phospholipase C (PIPLC) released CR1b from Chinese hamster ovary cells and E-CR from baboon erythrocytes, demonstrating that both of these proteins are glycophosphatidylinositol linked to the membrane. Thus, the data indicate that baboon CR1b, a homologue of the human CR1-like genetic element, encodes a glycophosphatidylinositol-linked protein that is the baboon E-CR.
Regulation of inducible nitric oxide synthase expression in IFN-gamma-treated murine macrophages cultured under hypoxic conditions.
Authors: Melillo G , Taylor L S , Brooks A , Cox G W , Varesio L 
Published: December 2022

Abstract
We recently reported that a hypoxia-responsive element mediates a novel pathway of transcriptional activation of the inducible nitric oxide synthase (iNOS) promoter in murine macrophages treated with IFN-gamma plus hypoxia (1% O2). In this study, we investigated the expression of NOS activity and the regulation of NOS induction in IFN-gamma treated ANA-1 murine macrophages or thioglycollate-elicited peritoneal macrophages cultured under hypoxic conditions. We found that murine macrophages stimulated with IFN-gamma plus hypoxia, despite a significant accumulation of iNOS mRNA, did not release nitrite into culture supernatant. However, cytosol from macrophages treated with IFN-gamma plus hypoxia contained significant levels of iNOS protein and enzymatic activity. Experiments in which cells were treated with IFN-gamma plus hypoxia and then cultured in normoxic conditions (20% O2) demonstrated that reoxygenation was required to achieve detectable accumulation of nitrite in the culture supernatant. Furthermore, we demonstrated that IL-4 inhibited IFN-gamma plus hypoxia-dependent induction of iNOS mRNA expression, iNOS protein, and enzymatic activity. Experiments in which ANA-1 macrophages were transfected transiently with the full-length iNOS promoter linked to a chloramphenicol acetyltransferase reporter gene demonstrated that IL-4 also down-regulated the IFN-gamma plus hypoxia-induced activation of the iNOS promoter. These data establish that hypoxia is a costimulus with IFN-gamma for the induction of iNOS activity in ANA-1 macrophages as well as in murine peritoneal macrophages, and they provide the first evidence that IL-4 inhibits hypoxia-inducible gene expression. In addition, our results suggest that hypoxia, which occurs in many pathologic conditions, may play an important role in the activation of murine macrophages.
A novel action of IL-13: induction of diminished monocyte glucocorticoid receptor-binding affinity.
Authors: Spahn J D , Szefler S J , Surs W , Doherty D E , Nimmagadda S R , Leung D Y 
Published: December 2022

Abstract
We have recently demonstrated that the combination of IL-2 and IL-4 blunts T cell responses to glucocorticoids in steroid resistant (SR) asthma by reducing glucocorticoid receptor (GCR)-binding affinity. Since immune activation appears to be involved in the acquisition of steroid resistance, we sought to identify whether other cytokines could also induce diminished GCR-binding affinity. In the current report, utilizing a [3H]dexamethasone radioligand-binding assay and Scatchard analysis, we found that IL-13, a cytokine with similar actions as IL-4, could induce diminished GCR binding-affinity (GCR Kd = 34.4 +/- 2.3 nM with IL-13 vs Kd = 8.8 +/- 0.7 nM for unstimulated control cells; p &lt; 0.001) in PBMC from normal subjects. In contrast, PBMC incubated with IL-1, IL-3, IL-5, IL-7, IL-8, IL-12, or granulocyte-macrophage-CSF had no effect on GCR-binding affinity; and no additive effect to the decreased GCR-binding affinity was noted when IL-13 was cocultured with IL-2 or IL-4. The cell target of IL-13-induced GCR effects was studied and found to reside in the non-T cell population; specifically, the monocyte fraction. To determine the functional significance of the decreased GCR-binding affinity, monocytes were pretreated with and without IL-1 3 prior to stimulation with LPS and hydrocortisone. IL-13 pretreatment of monocytes significantly diminished (p = 0.005) the suppressive effects of hydrocortisone on LPS-induced IL-6 production. IL-13, by virtue of its ability to induce diminished GCR-binding affinity, may contribute to impaired GC responsiveness during inflammatory illnesses.
The natural history of disease expression in CD4 and CD8 gene-deleted New Zealand black (NZB) mice.
Authors: Chen S Y , Takeoka Y , Ansari A A , Boyd R , Klinman D M , Gershwin M E 
Published: December 2022

Abstract
CD4 and CD8 gene-deleted New Zealand black (NZB) mice and, as controls, B6.CD4 -/-, B6.CD8 -/-, NZB, and B6 wild-type (wt) mice were studied for phenotypic and immunologic parameters to determine the contribution of CD4 and CD8 cell lineages in NZB mice. These studies suggest surprisingly that a number of abnormalities are not due to either CD4+ or CD8+ cell lineages but rather are most likely due to non-CD4+ and -CD8+ cell lineages and/or background genes. Such abnormalities include altered thymic architecture, decreased staining of MITS 33+ medullary thymocytes, and an increased frequency of splenic IgM secretory cells. In contrast, deletion of either CD4+ or CD8+ cells appears to differentially influence immunologic function. Deletion of CD8+ cells did not influence titers of spontaneously occurring anti-erythrocyte or anti-DNA autoantibodies. interestingly, 50% of NZB.CD4 -/- mice contained levels of anti-erythrocyte IgG and anti-ssDNA IgM autoantibodies; even without detectable CD4+ cells. Such deletion of CD4+ cells, while leading to marked decreases in the prototype cytokines that characterize Th1 and Th2 subsets in B6 mice, led to a marked increase in IFN-gamma and a moderate increase in IL-4 mRNA levels in NZB.CD4 -/- mice. These data suggest that whereas non-CD4+ and -CD8+ cell lineages and NZB background genes have a marked influence in the development of autoimmune abnormalities, CD4+ cells appear to play a major role in influencing the cytokine environment, whereas CD8+ cells appear to play a minor role.
Anti-IL-8 autoantibodies in alveolar fluid from patients with the adult respiratory distress syndrome.
Authors: Kurdowska A , Miller E J , Noble J M , Baughman R P , Matthay M A , Brelsford W G , Cohen A B 
Published: December 2022

Abstract
IL-8 is a potent neutrophil attractant and activator. IL-8 has been reported to be involved in the pathogenesis of several diseases, including rheumatoid arthritis, sepsis, psoriasis, and the adult respiratory distress syndrome (ARDS). Our previous studies demonstrated that high concentrations of IL-8 were present in alveolar fluids from patients with ARDS and were associated with increased mortality. In this study we report that a major portion of IL-8 in bronchoalveolar fluids from patients with ARDS is associated with anti-IL-8 autoantibody (anti-IL-8:IL-8 complexes). Free autoantibodies that recognize IL-8 were also detected in these fluids. Next, we examined the properties of anti-IL-8 autoantibodies present in lung fluids from ARDS patients and compared them with autoantibodies from normal plasma and arthritic synovial fluids. The anti-IL-8 autoantibody was polyclonal, and IgG3 and IgG4 were the primary IgG subclasses. Anti-IL-8:IL-8 complexes consisted of one IgG and one IL-8 molecule. In addition, anti-IL-8 autoantibody bound IL-8 with a high affinity (approximately 10(-12) M) and inhibited IL-8 interaction with its specific receptors on neutrophils. The results suggest that anti-IL-8 autoantibodies may regulate IL-8 activity.