bluuebunny/crossref_metadata_2025_split huggingface dataset:
In vivo activation of naive T cells by antigen-presenting B cells.
Authors: Morris S C , Lees A , Finkelman F D 
Published: December 2022

Abstract
In vivo experiments were performed to determine if the cross-linking of mlg on antigen-presenting B cells could induce them to present Ag to naive T cells in a stimulatory rather than a tolerogenic fashion. Mice were injected with a foreign mAb to a B cell Ag (Fc epsilon RII or CR1), and/or a self-anti-IgD mAb. Injection of either mAb alone failed to induce an Ab response; however, simultaneous injection of the foreign anti-B cell mAb plus the self-anti-IgD mAb stimulated a large response. Inasmuch as injection of the anti-IgD mAb should not have facilitated transfer of the foreign mAb to dendritic cells, this observation suggests that cross-linking of B cell mlg can induce B cells to acquire the ability to present Ag to naive T cells in an activating manner. Furthermore, when injected with anti-IgD mAb, both foreign anti-B cell mAbs were more potent in inducing Ab responses in this system than were isotype-matched control mAbs, consistent with the hypothesis that T cells were activated by Ag-presenting B cells. Results of dose-response and cell transfer studies, however, suggested that stringent cross-linking of B cell mlg on large numbers of B cells is required for B cell Ag presentation to induce T cell activation rather than tolerance. Therefore, these observations suggest that professional APCs usually are required to activate naive T cells, and that B cell Ag presentation can only activate naive T cells under unusual circumstances.
TGF-beta mediates natural suppressor activity of IL-2-activated lymphocytes.
Authors: Yamamoto H , Hirayama M , Genyea C , Kaplan J 
Published: December 2022

Abstract
In addition to generating cells with non-MHC-restricted cytotoxic activity that is characteristic of lymphokine-activated killer (LAK) cells, in vitro cultures of lymphocytes with relatively high concentrations of IL-2 generate cells that simultaneously exhibit two distinct types of suppressor activities: veto, the ability of cells to specifically suppress generation of allo-CTL against their own histocompatibility Ags; and natural suppression, the ability of these same cells to nonspecifically suppress the generation of allo-CTL against both their own and unrelated cell surface Ags. In contrast to veto, which is known to require cell-cell contact between veto-active cells and precursors of CTL, natural suppression is known to be mediated by soluble factors. To identify and characterize suppressor factors that might mediate the natural suppressor activity of IL-2-activated lymphocytes, murine spleen cells were cultured with 1000 U/ml IL-2, and, after varying periods of incubation, their LAK cytolytic activity and natural suppressor activity was determined and cell supernatants were collected and tested for their effects on mixed lymphocyte culture-induced generation of allo-CTL. Like the IL-2-activated lymphocytes themselves, supernatants of these cells nonspecifically inhibited mixed lymphocyte culture-induced generation of allo-CTL. Rabbit anti-TGF-beta specifically neutralized the suppressive effects of both LAK cell supernatants and the IL-2-activated lymphocytes themselves. These findings indicate that TGF-beta is the primary mediator of the natural suppressor activity of IL-2-activated lymphocytes.
Proteolytic processing of ovalbumin and beta-galactosidase by the proteasome to a yield antigenic peptides.
Authors: Dick L R , Aldrich C , Jameson S C , Moomaw C R , Pramanik B C , Doyle C K , DeMartino G N , Bevan M J , Forman J M , Slaughter C A 
Published: December 2022

Abstract
The identification of genes in the class II region of the MHC that are homologous to genes encoding subunits of the proteasome has led to intense interest in the possible role of this enzyme in the proteolytic processing of polypeptide Ags. We have tested the ability of the 20S proteasome to produce peptides that can be presented by class I molecules as targets for killing by OVA-specific and beta-galactosidase-specific CTL clones. Samples of intact OVA and beta-galactosidase were subjected to digestion in vitro by 20S proteasome purified from bovine red cells and the resulting peptide mixtures were fractionated by reverse-phase HPLC. The fractions were tested for their ability to sensitize appropriate mouse target cells for lysis by specific CTL clones. In both cases, components that under all chromatographic conditions eluted with retention times indistinguishable from synthetic peptides representing known epitopes of the naturally processed proteins were found to be able to sensitize the target cells. Moreover, in the case of OVA, the presence of the expected target peptides was demonstrated directly by amino acid sequence and mass spectrometric analysis. The results demonstrate that the pure 20S proteasome is capable of generating antigenic peptides from two proteins for presentation by class I molecules without the participation of additional components of the protein degradation system. This finding is consistent with the hypothesis of proteasome involvement in Ag processing in vivo.
Preferential VH gene usage in rabbit Ig-secreting heterohybridomas.
Authors: Raman C , Spieker-Polet H , Yam P C , Knight K L 
Published: December 2022

Abstract
B cells from leukemic rabbits preferentially use a single VH gene, VH1, in their VDJ gene rearrangements. To determine whether Ig-secreting B cells from normal rabbits also preferentially use VH1, we generated rabbit X mouse heterohybridomas that stably secreted rabbit Ig that expressed VHa allotypic specificities and analyzed the VH genes used in their VDJ gene rearrangements. We cloned the VDJ genes from nine heterohybridomas, and by comparing the restriction map of the DNA immediately 5' of the translational start site of these VDJ genes to that of the same region 5' of VH1, we showed that eight of the nine heterohybridoma clones use VH1. Comparison of the nucleotide sequences of the eight VH1-using VDJ genes with the nucleotide sequence of germ-line VH1 showed that each of them had somatically diversified. The diversified regions included clustered nucleotide changes and codon insertions and deletions, such as would be expected if the diversification process involved somatic gene conversion. We searched our database of germ-line VH genes for genes that could serve as donors for the gene conversion events, and we identified potential VH donor genes for five regions of diversification. One of these regions of diversification spanned at least 132 bp and included a codon insertion as well as 15 nucleotide changes. The data confirm that Ab diversity may be generated by a somatic gene conversion-like mechanism. The results directly demonstrate that Ig-secreting B cells from normal rabbits preferentially use VH1 in their VDJ gene rearrangements.
Use of global amino acid replacements to define the requirements for MHC binding and T cell recognition of moth cytochrome c (93-103).
Authors: Reay P A , Kantor R M , Davis M M 
Published: December 2022

Abstract
Substitution with all naturally occurring L-amino acids at each of 11 residues of the IEk-restricted month cytochrome c (93-103) epitope has allowed us to analyze the requirements for MHC binding and T cell recognition to a level of definition not previously possible. Substitutions at only three positions systematically affect MHC binding and three others appear to be the major TCR contacts. Interestingly, changing residues involved in MHC binding can ablate T cell recognition without altering MHC association. Additionally, residue identity at two positions that do not appear critical for MHC binding, nor to be involved in specific T cell contact, nonetheless dramatically affect T cell responses. This suggests that peptides differing only slightly in sequence can have significantly altered conformations within the class II MHC binding groove. We have also developed a simple scoring program that uses the binding data to quantitate how well a given peptide fits the MCC motif. All strongly immunogenic IEk-restricted epitopes score highly (&gt; or = 0.70, where 1.0 is perfect concordance), and only 3% of all potential nonameric peptides in the two main protein sequence databases have scores greater than 0.70. This indicates that the global amino acid replacement approach using a single peptide is an efficient means of deriving binding motifs for a given class II MHC molecule, and should aid in the identification of novel T cell epitopes.
Contribution of antibody-secreting cells induced in mucosal lymphoid tissues of pigs inoculated with respiratory or enteric strains of coronavirus to immunity against enteric coronavirus challenge.
Authors: VanCott J L , Brim T A , Lunney J K , Saif L J 
Published: December 2022

Abstract
Two antigenically related porcine coronaviruses, transmissible gastroenteritis virus (TGEV) which infects primarily the intestinal tract and causes severe diarrhea, and porcine respiratory coronavirus (PRCV) which infects the respiratory tract and causes subclinical or mild respiratory infections, presented a unique opportunity to study the interrelationship of gut-(GALT) and bronchus-associated lymphoid tissues (BALT) and their contribution to protective immunity against TGEV infection. Pigs were inoculated oral-nasally with TGEV or with PRCV at eleven days of age and challenged 24 days later with TGEV. All pigs initially given TGEV developed diarrhea and were completely protected against disease upon challenge. In contrast, pigs given PRCV had no clinical disease and shed virus in nasal secretions only; after challenge, 5 of 12 pigs developed diarrhea. Virus-specific IgG and IgA Ab-secreting cells (ASC) were enumerated by ELISPOT in the mesenteric and bronchial lymph nodes, spleens, and gut lamina propria at challenge and various post challenge days. Before challenge, in pigs exposed to TGEV, IgA-ASC in the duodenum and jejunum constituted the major ASC response. Conversely, PRCV-exposed pigs had mainly IgG-ASC in bronchial lymph nodes, with low ASC responses in the gut. After challenge, numbers of IgG-ASC increased rapidly in the gut lamina propria and mesenteric lymph nodes of only PRCV-primed pigs. Our results suggest that virus-specific IgG-ASC precursors derived in BALT of PRCV-primed pigs may migrate to the gut in response to TGEV challenge and contribute to the partial protection observed. The presence of IgA-ASC in the gut lamina propria of TGEV-primed pigs at the time of challenge correlated with complete protection against TGEV challenge. Thus a dichotomy exists in the BALT and GALT ASC responses; immunization via BALT induced a systemic type of response (IgG-ASC) and provided imperfect protection against an enteric pathogen, whereas immunization via GALT induced IgA-ASC and provided complete protection.
Pulmonary epithelial cells facilitate TNF-alpha-induced neutrophil chemotaxis. A role for cytokine networking.
Authors: Smart S J , Casale T B 
Published: December 2022

Abstract
TNF-alpha and neutrophils are postulated to play important roles in several inflammatory lung diseases. Thus, we examined TNF-alpha-induced neutrophil migration through polycarbonate filters and human pulmonary type II-like epithelial (A549) cells cultured as monolayers on these filters. TNF-alpha induced both dose- and time-dependent migration of neutrophils across both barriers, but migration across A549 cells was much greater than that across naked filters. Migration of neutrophils across both barriers was completely inhibited by anti-TNF-alpha. Furthermore, supernatants of TNF-alpha (10(-9) M)-stimulated A549 monolayers induced threefold greater migration of neutrophils across naked filters than 10(-9) M TNF-alpha itself, suggesting release of soluble chemotactic factor(s). Pretreatment of A549 monolayers with actinomycin D inhibited both the production of soluble chemotactic factors and TNF-alpha-induced transcellular migration. Supernatants from TNF-alpha-stimulated A549 cells contained significant concentrations of IL-8, and coincubation of these supernatants with anti-IL-8 decreased supernatant-induced chemotaxis. Finally, coincubation of TNF-alpha with anti-IL-8 during transmigration experiments partially inhibited neutrophil migration through A549 monolayers. Therefore, pulmonary type II epithelial cells facilitate TNF-alpha-induced transcellular migration of neutrophils through the production of soluble protein synthesis-dependent chemotactic factors, including IL-8. These data support the concepts of cytokine networking in inflammatory cell recruitment and an active role for pulmonary epithelium in lung inflammation.
Autoreactive epitope profiles of the proliferating cell nuclear antigen define two classes of autoantibodies.
Authors: Brand S R , Bernstein R M , Mathews M B 
Published: December 2022

Abstract
The proliferating cell nuclear antigen (PCNA) is a conserved protein required for cellular DNA replication. PCNA was first recognized using serum from the autoimmune disease SLE. To analyze the regions on PCNA that confer autoantibody binding, we modified the cDNA encoding full-length PCNA to generate a series of amino terminal, carboxyl terminal and internally deleted constructs, which were transcribed and then translated in vitro using the wheat germ cell-free translation system. An immunoprecipitation assay was used to study the ability of these mutated forms of PCNA to bind anti-PCNA Abs from patients with SLE. Eight of the ten sera studied required a protein of nearly full length for binding: antigenicity was abrogated by removal of 39 amino acids from the amino terminus, by various internal deletions, or by the removal of 15 (but not 11) amino acids from the carboxyl terminus. The remaining two sera exhibited an Ab-binding specificity to the carboxyl-terminally truncated proteins similar to that of the majority of anti-PCNA sera, but their specificity was different in the amino terminus: these sera were able to recognize PCNA lacking over 40% of sequence in the amino terminus, but they did not bind proteins with short internal deletions in that region. Thus, these epitopes appear to be conformational and distinguish two classes of autoimmune sera.
Chemically selected subclones of the CEM cell line demonstrate resistance to HIV-1 infection resulting from a selective loss of NF-kappa B DNA binding proteins.
Authors: Qian J , Bours V , Manischewitz J , Blackburn R , Siebenlist U , Golding H 
Published: December 2022

Abstract
To delineate cellular genes that are required for optimal HIV-1 infection, CEM cells were subjected to treatment with the chemical mutagen ethylmethanesulfonate (EMS) and subclones were selected based on their increased resistance to HIV-1 infection and reduced syncytium formation, despite relatively normal CD4 expression (20,000 to 25,000 receptors/cell). Two subclones with this phenotype demonstrated a diminished capacity of HIV-1 long terminal repeat-chloramphenicol acetyl transferase expression either after treatment with the protein kinase C activator PMA, or through Tat-mediated transactivation. In this study, we show that the cellular levels of the NF-kappa B DNA binding proteins (but not AP1 or SP1) are markedly reduced in these cell mutants both at the mRNA and protein levels, resulting in reduced nuclear localization of p50/p65 after PMA induction or treatment with the lymphokine TNF-alpha. Transient reconstitution with a plasmid expressing p50 resulted in partial recovery of PMA-inducible LTR-chloramphenicol acetyl transferase expression. These data suggest that, at least in the CEM T cell line, a selective reduction in the NF-kappa B DNA binding proteins is sufficient to curtail HIV-1 infection.
Regulatory effects of prostaglandin E2 on the growth and differentiation of human B lymphocytes activated through their CD40 antigen.
Authors: Garrone P , Galibert L , Rousset F , Fu S M , Banchereau J 
Published: December 2022

Abstract
We have studied the effects of prostaglandin E2 (PGE2) on the growth and differentiation of human tonsillar B lymphocytes cultured in the CD40 system with or without IL-4 or IL-10. PGE2 (10(-9) to 10(-6) M) enhanced proliferation of B cells activated through their CD40 Ag, but not their Ig secretion. PGE2 further potentiated both IL-4- and IL-10-induced B cell growth as determined by [3H]TdR uptake and cellular enumeration. The IL-10-induced IgM, IgG, and IgA secretion was enhanced twofold to fourfold after addition of PGE2, whereas IL-4-induced IgG and IgE secretion was inhibited. The IgE production was particularly sensitive as an approximately 90% inhibition was obtained for 10(-7) M PGE2. In addition, PGE2 inhibited IgE production by naive surface IgD+ B cells cultured in the CD40 system, suggesting that PGE2 may interact with mechanisms involved in IgE switching. PGE2 displayed similar effects on cytokine-induced proliferation and Ig secretion of B cells activated by anti-CD40 Abs used in a soluble form. Finally, the PGE2 effects were mimicked by agents increasing cAMP, indicating that the PGE2 activities are likely to depend on the activation of the cAMP pathway. Altogether, the present data indicate that PGE2 stimulates human CD40-activated B cell growth, but differently modulates cytokine-induced differentiation. Thus, in microenvironments supporting the development of an immune response, the secretion of PGE2 by competent cells such as macrophages may participate in the regulation of the humoral response.
Failure to demonstrate long-lived MHC saturation both in vitro and in vivo. Implications for therapeutic potential of MHC-blocking peptides.
Authors: Ishioka G Y , Adorini L , Guery J C , Gaeta F C , LaFond R , Alexander J , Powell M F , Sette A , Grey H M 
Published: December 2022

Abstract
Peptides that bind with high affinity to class II MHC molecules can inhibit T cell activation both in vitro and in vivo. Thus, they have been suggested as potential therapeutic agents for MHC-associated autoimmune diseases. We have constructed nonnatural peptides with high affinity for certain disease-associated MHC alleles. More specifically, a particular peptide, designated as CY-760.50, was found to have a high binding affinity for DR1, slow dissociation kinetics after binding to MHC, and prolonged stability in human serum. However, when the ability of this peptide to block peptide presentation to an influenza hemagglutinin 307-319 peptide-specific, DR1-restricted T cell clone was examined, it was found that MHC blockade could only be achieved when high concentrations of peptide were present along with Ag in the fluid phase. Thus, pretreatment of APC with MHC class II blocker, followed by removal of unbound blocker, did not result in saturation of MHC molecules, because practically immediate reacquisition of Ag-presenting capacity was observed after removal of fluid phase blocker. The pharmacokinetic behavior and the duration of blocking activity of CY-760.50 were also examined in vivo, taking advantage of the fact that the mouse MHC class II molecule I-Ab also bound CY-760.50 with high affinity. CY-760.50 administered i.v. to C57BL/6 mice was rapidly cleared from the circulation and virtually undetectable in the serum 10 min after injection. This fast clearance rate was paralleled by a similarly short duration of the MHC blockade effect. These in vivo results have implications concerning the biology of peptide-MHC interactions, and suggest that MHC blockade may not be feasible as a therapeutic approach unless effective concentrations of inhibitor can be maintained over extended periods of time in the extracellular fluids.
Up-regulation of c-myc induces the gene expression of the murine homologues of p34cdc2 and cyclin-dependent kinase-2 in T lymphocytes.
Authors: Kim Y H , Buchholz M A , Chrest F J , Nordin A A 
Published: December 2022

Abstract
The expression and/or up-regulation of several early T cell activation genes is dependent on signals transmitted through the interaction of IL-2 and IL-2R well before entry of the cells into S phase. In these studies, murine G0 T cells activated by immobilized anti-CD3 and subsequently blocked in late G1 expressed normal surface levels and mRNA for IL-2R alpha, IL-2R beta, and transferrin receptor (TfR). However, there was no expression of p34cdc2, and cyclin-dependent kinase (cdk)-2 was not up-regulated even in the presence of exogenous rIL-2. In addition the accumulation of c-myc-specific mRNA and protein was significantly reduced. Pretreatment of G0 T cells with c-myc antisense oligonucleotide effectively reduced the level of specific c-myc protein induced by activation of the cells by immobilized anti-CD3. The presence of antisense c-myc oligonucleotide inhibited the expression of cdc2 and cdk2 without affecting the expression of IL-2R alpha and blocked the activated T cells in the G1 phase. Together these studies demonstrate that c-myc regulates the expression of these cdk and suggest a role for c-myc in the G1/S transition.
Immunological mimicry between N-acetyl-beta-D-glucosamine and cytokeratin peptides. Evidence for a microbially driven anti-keratin antibody response.
Authors: Shikhman A R , Cunningham M W 
Published: December 2022

Abstract
We discovered recently that a subset of mouse anti-streptococcal mAbs cross-reacted with N-acetyl-beta-D-glucosamine (GlcNAc) and certain cytoskeletal proteins, and recognized both carbohydrate and peptide antigenic determinants. To further study the nature and biologic significance of immunologic mimicry between carbohydrate and peptide Ags, eight human hybridomas secreting anti-GlcNAc mAbs were produced by in vitro stimulation of PBL with streptococcal peptidoglycan-polysaccharide complexes and pokeweed mitogen. All human anti-GlcNAc mAbs described in this study were shown to express marked cross-reactivity with keratin from human skin in the ELISA and Western immunoblot. Mapping of the mAbs with overlapping synthetic decapeptides of the entire amino acid sequence of human cytokeratin 14 revealed that human anti-GlcNAc mAbs recognized specific cytokeratin decapeptides. Four human anti-GlcNAc mAbs recognized a single cytokeratin decapeptide whereas two mAbs reacted with several individual peptide epitopes in different fragments of cytokeratin 14. In addition, two mAbs, 1.C8 and 9.B12, reacted with multiple cytokeratin decapeptides, predominantly in the head domain of the molecule, and their reactivity correlated with positive binding of the mAbs to cytokeratin 14 in the Western immunoblot and with positive staining of human epidermis in the indirect immunofluorescent assay. Finally, we demonstrated that Abs to keratin and synthetic keratin decapeptides were induced in BALB/c mice immunized with GlcNAc-BSA but not with BSA, suggesting that the anti-keratin Ab response in vivo may be driven by nonkeratin Ags containing terminal O-linked GlcNAc.