bluuebunny/crossref_metadata_2025_split huggingface dataset:
Potentiation of C1 inhibitor by glycosaminoglycans: dextran sulfate species are effective inhibitors of in vitro complement activation in plasma.
Authors: Wuillemin W A , te Velthuis H , Lubbers Y T , de Ruig C P , Eldering E , Hack C E 
Published: January 2023

Abstract
Activation of the complement system may contribute to the pathogenesis of many diseases. Hence, an effective inhibitor of complement might be useful to reduce tissue damage. Some glycosaminoglycans (GAG), such as heparin, are known to inhibit the interaction of C1q with activators and the assembly of the classical and the alternative pathway C3 convertases. Furthermore, they may potentiate C1 inhibitor-mediated inactivation of C1s. To search for potential complement inhibitors, we systematically investigated the complement inhibitory properties of various synthetic and naturally occurring GAG (dextran sulfates 500,000 and 5,000, heparin, N-acetylheparin, heparan sulfate, dermatan sulfate, and chondroitin sulfates A and C). First, we assessed the effect of GAG on the second-order rate constant of the inactivation of C1s by C1 inhibitor. This rate constant increased 6- to 130-fold in the presence of the GAG, dextran sulfate being the most effective. Second, all tested GAG were found to reduce deposition of C4 and C3 on immobilized aggregated human IgG (AHG) and to reduce fluid phase formation of C4b/c and C3b/c in recalcified plasma upon incubation with AHG. Dextran sulfate again was found to be most effective. We conclude that GAG modulate complement activation in vitro and that the low molecular weight dextran sulfate (m.w. 5000) may be a candidate for pharmacologic manipulation of complement activation via potentiation of C1 inhibitor.
Pathogenetic effector function of CD4-positive T helper 1 cells in hepatitis B virus transgenic mice.
Authors: Franco A , Guidotti L G , Hobbs M V , Pasquetto V , Chisari F V 
Published: January 2023

Abstract
The pathogenetic effector functions of hepatitis B virus (HBV)-specific CD4+, Th1 cells were analyzed in two inbred lineages of HBV transgenic mice, one of which overexpresses the HBV large envelope protein rendering the hepatocytes hypersensitive to the cytopathic effects of IFN-gamma, and another that expresses all of the HBV proteins and replicates the virus in the liver. Transfer of HBV envelope-specific Th1 cells resulted in recognition of viral Ag expressed by hepatic nonparenchymal cells, cytokine release, and a transient necroinflammatory liver disease in both lineages. The liver disease was very severe in the IFN-gamma-sensitive lineage, and it was less severe in the lineage that replicates the HBV genome; nonetheless, in this lineage the Th1 cytokines produced by these cells suppressed viral replication in the liver. These results demonstrate that CD4+ T cells with a Th1 functional phenotype can perform pathogenetic and antiviral effector functions in vivo. This suggests that CD4+ T cells can contribute directly to disease pathogenesis and inhibit viral replication during HBV infection.
Autoantibodies to ribosomal P proteins penetrate into live hepatocytes and cause cellular dysfunction in culture.
Authors: Koscec M , Koren E , Wolfson-Reichlin M , Fugate R D , Trieu E , Targoff I N , Reichlin M 
Published: January 2023

Abstract
Abs to ribosomal P protein have been shown to bind a membrane form of the P0 38-kDa ribosomal phosphoprotein. This study shows that after affinity-purified Abs to ribosomal P proteins bind living HepG2 cells, they then penetrate these live cells and cause cellular dysfunction. Binding and penetration of anti-P Abs is the property of F(ab')2 fragments as well as whole IgG molecules showing that neither binding nor penetration depends on Fc fragments or their cognate receptors. Confocal microscopy shows that internalized Ab concentrates in perinuclear vesicles (presumably lysosomes), but substantial quantities of Ab are also found in the cytosol. This intracellular Ab adversely affects the synthesis of apolipoprotein B resulting in a threefold increase in cellular cholesterol with lipid droplet accumulation as seen in some chronic liver diseases. It also has a profound inhibitory effect on global protein synthesis as measured by [35S]methionine incorporation. These studies therefore describe a model of cellular injury effected by specific Ab to ribosomal "P" protein that may underlie certain forms of autoimmune hepatic diseases.
Diphtheria Toxin
Authors: Povitzky Olga R. 
Published: January 2023

Abstract
The preparation of diphtheria toxins from the time of its discovery by Behring has been repeatedly investigated with the development of many changes in its preparation, but it still presents many difficulties. The urgent need of strong potent toxins for the Ramon flocculation tests for titration of diphtheria antitoxins, and also for the preparation of toxin-antitoxin mixtures and toxoids for immunization, led the writer at the instigation of Dr. Park to add her attempts to the further solving of this problem. The Ramon flocculation test for titrating toxins was of greatest value in the following studies. It would have been indeed a difficult, tedious and expensive task, to check the numerous lots of toxins prepared by guinea pig instead of the test tube tests. By the Ramon tests, different lots of toxins could be tested on different days of growth and the results known from twenty minutes to twenty-four hours, depending on the strength of the toxin.
Modulation of T Cell Cytokine Profiles and Peptide-MHC Complex Availability In Vivo by Delivery to Scavenger Receptors via Antigen Maleylation
Authors: Singh Nagendra , Bhatia Sumeena , Abraham Roshini , Basu Sandip K. , George Anna , Bal Vineeta , Rath Satyajit 
Published: January 2023

Abstract
We have previously shown that conversion of proteins to scavenger receptor (SR) ligands by maleylation increases their immunogenicity. We now show that maleyl-Ag-immune spleen cells make relatively more IFN-γ and less IL-4 or IL-10 than native Ag-immune cells. This is also reflected in the IgG1:IgG2a ratios in Abs generated in vivo. SR engagement on macrophages does not alter their surface levels of the adhesive/costimulatory molecules CD11a/CD18, CD11b/CD18, CD24, CD54, or CD40, nor does it enhance their ability to support anti-CD3-driven proliferation of naive T cells in vitro. Costimulatory molecules implicated in differential Th1/Th2 commitment—CD80, CD86, and IL-12—are not inducible by SR ligation. In addition to macrophages and dendritic cells, B cells also show receptor-mediated uptake and enhanced presentation of maleyl-Ags. Using a monoclonal T cell line to detect peptide-MHC complexes expressed on spleen cells in Ag-injected mice, we find that higher levels of these complexes are generated in vivo from maleyl-proteins and they persist longer than those generated from the native protein. Together, these data suggest that in certain situations, the levels of cognate ligand available and/or the time course of their availability may play a major role in determining the cytokine profiles of the responding T cells in addition to the costimulatory signals implicated so far.
Rearrangement and Selection in the Developing Vκ Repertoire of the Mouse: An Analysis of the Usage of Two Vκ Gene Segments
Authors: Whitcomb Elizabeth A. , Brodeur Peter H. 
Published: January 2023

Abstract
Detailed analysis of the rearrangement and expression of two mouse Vκ genes has been used to examine B cell repertoire development. The Vκ1-A gene is used by a large proportion (9.6%) of splenic B cells in the adult primary repertoire, whereas the Vκ22 gene is used at a much lower frequency (0.16%). Consistent with these results, quantitative PCR (Q-PCR) assays revealed that the number of splenic B cells with rearranged Vκ1-A genes is much greater than the number with rearranged Vκ22 genes. Q-PCR was also performed on both normal bone marrow pre-B cells and transformed pre-B cells induced to rearrange their κ loci at high frequency. In contrast to splenic B cell rearrangements, the numbers of Vκ1-A and Vκ22 rearrangements in pre-B cells differ by only two- or threefold, suggesting that the intrinsic rearrangement frequencies of these two Vκ genes are not significantly different. Further evidence of disproportionate selection was obtained by comparing the percentages of productive rearrangements amplified from genomic splenic DNA. Sequence analysis showed 84% (37 of 44) of the Vκ1-A rearrangements but only 57% (29 of 51) of the Vκ22 rearrangements to be in-frame. Together these results suggest that B cells expressing Vκ1-A-encoded light chains are preferentially selected either in the periphery or in the transition from pre-B to B cell. Sequence data also reveal a surprisingly restricted diversity of VJ junctions, apparently due to biases introduced by the rearrangement mechanism.
Activation of the CD2 Pathway in Lamina Propria T Cells Up-Regulates Functionally Active AP-1 Binding to the IL-2 Promoter, Resulting in Messenger RNA Transcription and IL-2 Secretion
Authors: Gonsky Rivkah , Deem Richard L. , Hughes Christopher C. W. , Targan Stephan R. 
Published: January 2023

Abstract
The aim of this study was to identify molecular mechanisms involved in transcriptional regulation of IL-2 expression following CD2 and CD3 activation in lamina propria (LP) T cells. Studies used T cells from normal, ulcerative colitis, and Crohn’s disease mucosa and freshly isolated PBMC, PBMC stimulated with IL-2 alone, and PBMC stimulated with IL-2 and cocultured with B cell lines (LP-like T cells). Electrophoretic mobility shift assays were performed with nuclear extracts from cells activated with either anti-CD2 or anti-CD3 Abs. CD2 signaling in LPMC and LP-like T cells led to a pattern of sustained up-regulation of AP-1-binding complexes, whereas CD3 activation resulted in only transient up-regulation. While the pattern of regulation of AP-1 binding observed in normal, uninflamed, or inflamed Crohn’s disease LPMC is similar, differences in intensity of AP-1 binding were observed. Activation of LP-like T cells mimics the up-regulation of AP-1 with a kinetic profile similar to that observed with freshly isolated LPMC from Crohn’s disease-inflamed tissue. The AP-1 complex formed following CD2 activation is composed of jun/fos heterodimers. The CD2-enhanced responsiveness is reflected in functional analysis experiments utilizing transfection of both multimeric-TRE or IL-2 promoter-luciferase constructs directly into normal, ulcerative colitis, or Crohn’s disease LPMC. Our data suggest that activation of LP T cells from normal, ulcerative colitis, or Crohn’s disease mucosa through the CD2 pathway leads to induction of AP-1 complexes that bind to the IL-2 promoter, and may play a pivotal role in modulating IL-2 production in the gut.
An sLex-Deficient Variant of HL60 Cells Exhibits High Levels of Adhesion to Vascular Selectins: Further Evidence That HECA-452 and CSLEX1 Monoclonal Antibody Epitopes Are Not Essential for High Avidity Binding to Vascular Selectins
Authors: Wagers Amy J. , Stoolman Lloyd M. , Craig Ron , Knibbs Randall N. , Kansas Geoffrey S. 
Published: January 2023

Abstract
Selectins are carbohydrate-binding cell adhesion molecules that play a key role in the initiation of inflammatory responses. Several studies have suggested that the sialylated, fucosylated tetrasaccharide sialyl Lewis X (sLex) is an important component of leukocyte ligands for E- and P-selectin. We have identified a stable variant of the HL60 cell line, HL60var, which displays a nearly complete absence of staining with several mAb directed against sLex and/or sLex-related structures. HL60var also exhibits a concomitant increase in reactivity with mAb directed against the unsialylated Lewis X (Lex/CD15) structure. Despite this sLex deficiency, HL60var binds well to both E- and P-selectin. No significant differences in expression of α1,3-fucosyltransferases, C2GnT (Core2 transferase), or P-selectin glycoprotein ligand-1 between HL60var and typical sLexhigh HL60 cells were detected. Although the precise molecular basis for the sLex−/low phenotype of HL60var remains uncertain, flow cytometric analysis with the sialic acid-specific Limax flavus lectin revealed a sharp reduction in HL60var surface sialylation. Thus, the loss in mAb reactivity may result from a loss of sialic acid residues from the mAb carbohydrate epitope. However, binding of HL60var to E- and P-selectin remains sensitive to neuraminidase treatment. Taken together, these data indicate that high levels of surface sLex and/or related epitopes are not essential for interactions with vascular selectins, implying that as yet unidentified sialylated, fucosylated structures serve as physiologically relevant ligands for E- and P-selectin.
Cutting Edge: Novel RNA Ligands Able to Bind CD4 Antigen and Inhibit CD4+ T Lymphocyte Function
Authors: Kraus Elmar , James William , Barclay A. Neil 
Published: January 2023

Abstract
The value of high affinity-specific reagents in immunology is exemplified by the use of mAbs. Recent in vitro selection methods suggested that oligonucleotides may provide a useful alternative, especially where Abs have been insufficient thus far. We used a systematic evolution of ligands by exponential enrichment (SELEX) procedure to derive high affinity oligonucleotide ligands (aptamers) recognizing CD4. These RNase-resistant aptamers bound with high affinity and specificity as demonstrated using BIAcore (Stevenage, U.K.) technology. They also bound native CD4 on rat lymphocytes and specifically interfered with labeling by high affinity mAbs. All aptamers recognized the same binding site in the CDR2-like region in domain 1 of CD4. The applicability of these aptamers for immunologic studies was clearly demonstrated by their ability to block a fully allogeneic MLR in a CD4-specific manner. The high affinity and stability of aptamers point to their value in the analysis and functional manipulation of the immune system.
Early Preferential Stimulation of γδ T Cells by TNF-α
Authors: Lahn Michael , Kalataradi Harshan , Mittelstadt Peter , Pflum Elizabeth , Vollmer Michaelann , Cady Carol , Mukasa Akiko , Vella Anthony T. , Ikle David , Harbeck Ronald , O’Brien Rebecca , Born Willi 
Published: January 2023

Abstract
Although recent findings indicate that γδ T cells influence both early innate and Ag-specific adaptive host responses, it has remained unclear what triggers γδ T cell reactivity. Investigating very early T cell activation in mouse and human models of bacterial infection, we measured CD69 expression as an indicator of early cellular activation. Both murine αβ and γδ T cells responded polyclonally to systemic bacterial infections, and to LPS. However, γδ T cells responded more strongly to the bacteria and to LPS. In vitro LPS-stimulated human T cells showed a similar differential response pattern. We identified TNF-α as mediator of the early differential T cell activation, and of differential proliferative responses. The stronger response of γδ T cells to TNF-α was correlated with higher inducible expression levels of TNF-Rp75. Among unstimulated splenocytes, more γδ T cells than αβ T cells expressed CD44 at high levels. The data suggest that TNF-Rp75 determines the differential T cell reactivity, and that most γδ T cells in the normal spleen are present in a presensitized state. As TNF-α stimulates activated T cells, it may early preferentially connect γδ T cell functions with those of cells that produce this cytokine, including activated innate effector cells and Ag-stimulated T lymphocytes.
In Vivo Inflammatory Response to a Prototypic B Cell Superantigen: Elicitation of an Arthus Reaction by Staphylococcal Protein A
Authors: Kozlowski Lisa M. , Li Weiping , Goldschmidt Michael , Levinson Arnold I. 
Published: January 2023

AbstractStaphylococcal protein A (SpA) is representative of a new class of Ags, the B cell superantigens (SAgs). These SAgs, unlike conventional Ags, bind to the Fab regions of Ig molecules outside their complementarity-determining regions. In addition, B cell SAgs can react with a substantial amount of a host’s serum Igs by virtue of their ability to interact with many members of an entire variable heavy chain (VH) or variable light chain gene family. For example, SpA reacts with the Fabs of most human Igs using heavy chains from the VH3 gene family (VH3+). Members of this gene family are expressed on 30 to 60% of human peripheral B cells. We sought to determine whether the interaction of a B cell SAg with its reactive Igs can elicit immune complex-mediated tissue injury. Using the Arthus reaction in rabbits as an in vivo model of immune complex-mediated tissue inflammation, we demonstrated that untreated rabbits, which were administered SpA intradermally (i.d.), do not develop a cutaneous inflammatory response. However, when rabbits were pretreated i.v. with human IgG (hIgG), i.d. injections of SpA induced an inflammatory response with the classical histologic features of an Arthus reaction. To determine whether this Arthus-like response occurred via a B cell superantigenic mechanism, the rabbits were pretreated with VH3-depleted hIgG and then were administered SpA i.d. We found that the induction of a prominent inflammatory response by SpA was dependent upon the presence of VH3+ molecules in the hIgG pretreatment. These results provide compelling evidence that an interaction of the B cell SAg, SpA, with its reactive (VH3+) IgGs leads to an immune complex-mediated inflammatory response in vivo.
Two T Cell Epitopes from the M5 Protein of Viable Streptococcus pyogenes Engage Different Pathways of Bacterial Antigen Processing in Mouse Macrophages
Authors: Delvig Alexei A. , Robinson John H. 
Published: January 2023

Abstract
We studied the mechanisms of MHC class II-restricted bacterial Ag processing of the surface fibrillar M5 protein from viable Streptococcus pyogenes in murine macrophages. Two previously defined T cell epitopes were studied using T cell hybridomas specific for 308–319/Ad, associated with the cell wall on the surface of streptococci, and 17–31/Ed, located at the protruding amino terminus of M5. Studies with metabolic inhibitors showed that slow (1 h) processing of M5 308–319 occurred in late endosomes and was dependent on newly synthesized MHC class II molecules and microtubules and on communications between early and late endosomes, consistent with engagement of the classical MHC class II processing pathway. In contrast, fast (15 min) bacterial Ag processing of 17–31 occurred in early endosomes independently of newly synthesized MHC class II molecules and microtubules and of trafficking between early and late endosomes, consistent with the recycling MHC class II processing pathway. Finally, bacterial Ag processing of the epitopes exhibited differential sensitivity to blocking with anti-MHC class II Abs. Thus, two T cell epitopes of a single protective Ag from the surface of whole bacteria are routed to distinct MHC class II processing pathways.
T Cells Expressing Receptors of Different Affinity for Antigen Ligands Reveal a Unique Role for p59fynin T Cell Development and Optimal Stimulation of T Cells by Antigen
Authors: Utting Oliver , Teh Soo-Jeet , Teh Hung-Sia 
Published: January 2023

AbstractSignaling from the TCR involves the protein tyrosine kinase p59fyn (Fyn). Previous studies have shown that T cell development occurs normally in Fyn−/− mice. In this study, we investigated the requirement for Fyn in the development and function of T cells expressing either the transgenic 2C TCR, with high affinity for its Ag ligand, or the transgenic H-Y TCR, representative of a low affinity TCR. Although Fyn was not essential for positive selection of thymocytes expressing either the 2C or the H-Y TCR, it facilitated the down-regulation of the heat-stable Ag in positively selected CD4−CD8+ thymocytes in both 2C and H-Y mice. Negative selection of thymocytes expressing the H-Y TCR also occurs efficiently in Fyn−/− mice. However, in Fyn−/− mice, there was a preferential survival of thymocytes that expressed higher levels of the CD8 coreceptor and the transgenic TCR. Positively selected CD4−CD8+ thymocytes and peripheral T cells expressing either the 2C or the H-Y TCR differed in their requirement of Fyn for optimal proliferation responses to stimulation by antigenic ligands. Whereas 2C Fyn−/− or 2C Fyn+/+ thymocytes and peripheral T cells responded optimally to stimulation by the specific Ag, H-Y Fyn−/− thymocytes and peripheral T cells were hyporesponsive compared with Fyn+/+ cells. Significantly, in response to a defined low affinity ligand, both 2C Fyn−/− thymocytes and peripheral T cells required Fyn for optimal response to Ag stimulation. Thus, Fyn plays a role during thymocyte development and is required for optimal responses to low affinity/avidity ligands.
FTY720, a Novel Immunosuppressant, Induces Sequestration of Circulating Mature Lymphocytes by Acceleration of Lymphocyte Homing in Rats. II. FTY720 Prolongs Skin Allograft Survival by Decreasing T Cell Infiltration into Grafts But Not Cytokine Production In Vivo
Authors: Yanagawa Yoshiki , Sugahara Kunio , Kataoka Hirotoshi , Kawaguchi Takafumi , Masubuchi Yumi , Chiba Kenji 
Published: January 2023

AbstractFTY720, a novel immunosuppressant, prolonged the survival of WKAH skin allografts transplanted into MHC-incompatible F344 rats. In this allograft model, the median survival time of the control group was 7 days, whereas those of the groups given FTY720 orally at 0.1 mg/kg and cyclosporin A (CsA) at 10 mg/kg were 10.5 and 11 days, respectively. In contrast, FTY720 (0.1 mg/kg) combined with CsA (10 mg/kg) synergistically prolonged allograft survival with a median survival time exceeding 70 days. To elucidate the mechanisms of this remarkable synergistic effect, mRNA expressions of IL-2 and IFN-γ and that of CD3 (δ-chain), which reflects T cell infiltration, in allografts were temporally analyzed using a semiquantitative PCR method. In WKAH skin allografts, mRNA levels of IL-2, IFN-γ, and CD3 were increased as compared with isograft controls, peaking on days 4 to 5. CsA (10 mg/kg) significantly inhibited elevations of IL-2 and IFN-γ mRNA, while slightly inhibiting that of CD3 mRNA in allografts. On the contrary, FTY720 (0.1 mg/kg) markedly inhibited the elevation of CD3 mRNA, while slightly inhibiting those of IL-2 and IFN-γ mRNA. FTY720 (0.1 mg/kg) combined with CsA (10 mg/kg) almost completely suppressed the intragraft expressions of mRNA for IL-2, IFN-γ, and CD3. Immunohistochemical staining and flow cytometric analysis also confirmed that FTY720 decreased T cell infiltration into allografts. From these results, the synergistic effect of FTY720 combined with CsA on prolongation of allograft survival is presumably based on the respective inhibitions of T cell infiltration and cytokine production in grafts.