bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intramolecular mimicry. Identification and analysis of two cross-reactive T cell epitopes within a single protein.
Authors: Hagerty D T , Allen P M 
Published: January 2023

Abstract
The recognition of peptide Ags by T cells through the TCR has exquisite specificity. Cross-reactive T cell responses have been described; however, the structural basis for these responses is not known. We show that two peptides derived from the same protein can exhibit sufficient structural homology, despite minimal structural identity, to elicit cross-reactive T cell responses. In addition, we explore the structural basis for cross-reactivity. T cell hybridomas recognizing PiM and PiZ allelic forms of human alpha 1-antitrypsin (hAAT) each recognized both PiM 205-220 and PiM 335-350. These two peptides possessed primary sequence identity at only two of 16 amino acid residues. Cross-reactive peptides also exhibited homology at the bulk T cell level because lymph node T cells primed with one peptide proliferated to the other peptide in vitro. Critical amino acids for the responding T cells were determined, and the core was transferred into the less reactive peptide in an attempt to increase homology by increasing sequence identity. Interestingly, as identity increased, homology decreased: peptides with the least primary sequence identity appeared most homologous to the T cells. These results have important implications for understanding the development of autoimmune diseases, and imply that minimal obvious primary sequence identity may be sufficient to initiate cross-reactive T cell responses. The ability of structurally dissimilar peptides to mimic each other when bound to a class II MHC molecule may also be important to the understanding of T development and autoimmunity.
The identification and cloning of a murine major basic protein gene expressed in eosinophils.
Authors: Larson K A , Horton M A , Madden B J , Gleich G J , Lee N A , Lee J J 
Published: January 2023

Abstract
The existence of a murine homologue of the major basic protein (MBP) found in human eosinophil granules was initially hypothesized from structural similarities at the electron microscopic level. The results presented in this study have extended these observations by describing the identification/purification of a mouse MBP (mMBP) and the cloning of the gene encoding this eosinophil granule protein. Using protein purification methodologies with extravascular eosinophils, an mMBP homologue has been identified on the basis of strong (64%) N-terminal sequence homology with the mature human MBP (hMBP). Since hMBP results from a proteolytic cleavage of a precursor molecule, this sequence conservation suggests that the mouse granule protein is processed by a similar mechanism. The gene encoding mMBP was isolated using a hMBP cDNA clone as a heterologous probe in low criteria screens of mouse genomic and cDNA libraries. The genomic structure and nucleotide sequence of the mMBP exons are well conserved with the human gene, although homology alignments of the encoded proteins show that extensive sequence conservation occurs only in the mature portion of the MBP molecules. Expression data demonstrate that this gene is transcriptionally active in tissues containing eosinophil progenitor cells, such as femoral bone marrow. Genomic Southern blots using the mMBP gene at reduced stringency reveal the potential existence of a second, more divergent MBP-like sequence in the mouse. This suggests that, as with guinea pigs, the mouse genome may also encode the eosinophil major basic protein from more than one gene.
Molecular cloning and chromosomal localization of the mouse decay-accelerating factor genes. Duplicated genes encode glycosylphosphatidylinositol-anchored and transmembrane forms.
Authors: Spicer A P , Seldin M F , Gendler S J 
Published: January 2023

Abstract
Regulation of complement activation is essential in the prevention of damage to autologous tissue. This activity is mediated by the presence of specific complement regulatory proteins on the surface of host cells. In humans, one molecule involved in this regulation is a 70-kDa glycoprotein that has been designated decay-accelerating factor (DAF). We present the full-length cDNA sequence and chromosomal localization of the mouse genetic homologue of the human DAF gene. Interestingly, two classes of cDNA clones were obtained that, rather than representing alternately spliced mRNAs, were derived from two separate but closely related linked genes. Both genes encoded proteins with an amino-terminal signal sequence, followed by four short consensus repeats and a domain rich in serine and threonine. Hydrophilicity plots and alignment with human DAF predicted that one gene encoded a glycosylphosphatidylinositol-anchored form of mouse Daf with 64% nucleotide and 47% amino acid identity to human DAF. The product encoded by the second gene was predicted to have an alternate amino-terminal signal sequence and carboxyl-terminal membrane-spanning and cytoplasmic domains. The two mouse Daf genes share 85% nucleotide and 78% amino acid identities, and have been designated Daf-glycosylphosphatidylinositol and Daf-transmembrane to reflect the two alternate mechanisms of membrane attachment. mRNA expression analysis indicated that the two mouse Daf genes were differentially expressed in the adult mouse. Chromosome localization studies mapped the mouse Daf genes to chromosome 1, where they segregated with the C4-binding protein (C4bp) gene.
Domains 1 and 4 of vascular cell adhesion molecule-1 (CD106) both support very late activation antigen-4 (CD49d/CD29)-dependent monocyte transendothelial migration.
Authors: Chuluyan H E , Osborn L , Lobb R , Issekutz A C 
Published: January 2023

Abstract
We investigated the role of the 6 domain (6D) and 7 domain (7D) forms of human VCAM-1 as counter-receptors for the alpha 4 beta 1 integrin (VLA-4) in monocyte migration induced by C5a. Across Chinese hamster ovary (CHO) cell monolayers transfected with VCAM-6D or VCAM-7D, monocyte migration was not inhibited by treatment of monocytes with mAb to CD18. Addition of mAb to alpha 4 to the CD18 mAb inhibited monocyte migration by 90% across CHO VCAM-6D and CHO VCAM-7D. mAbs to domain 1 (4B9) or domain 4 (GH12) of VCAM-1 each inhibited migration across CHO VCAM-7D partially, when monocytes were also treated with anti-CD18 mAb. When the VCAM-1 mAbs were combined, migration of these monocytes across CHO VCAM-7D was further inhibited to the same degree as with mAbs to alpha 4 plus CD18. IL-1-treated human umbilical vein endothelium (HUVE) supported CD18-independent, VLA-4-mediated monocyte migration to C5a. A mAb to domain 1 of VCAM-1 almost completely inhibited the CD18-independent migration across HUVE activated with IL-1 for 2 h or 20 h, but was less inhibitory when HUVE was treated with IL-1 for 5 h. However, when mAbs to domain 1 and domain 4 were combined, CD18-independent migration was inhibited completely under all conditions tested. These results suggest that either domain 1 or domain 4 of VCAM-1 can mediate VLA-4-dependent monocyte transendothelial migration, that VLA-4 interaction with these two domains can account for all of the VLA-4-mediated migration, and that the expression of VCAM-1 variants on HUVE depends partly on the duration of IL-1 activation.
Effect of liposome-mediated macrophage depletion on LPS-induced cytokine gene expression and radioprotection.
Authors: Salkowski C A , Neta R , Wynn T A , Strassmann G , van Rooijen N , Vogel S N 
Published: January 2023

Abstract
Tissue-specific cytokine mRNA expression was examined in mice that received LPS. In the liver, IL-6, IL-10, IL-12 (p40), and TNF-alpha were induced by 30 min after injection with LPS. In the spleen, IL-6 and TNF-alpha were induced by 30 min after LPS challenge, while increases in IL-10 and IL-12 (p40) were delayed in onset. GM-CSF, IFN-gamma, and IL-12 (p35) were not induced in the liver or spleen until 60 to 90 min after LPS injection. Mice were depleted of macrophages in their liver and spleen by i.v. injection of liposome-encapsulated dichloromethylene bisphosphonate (Cl2MBP). Induction of IL-1 beta, IL-6, IL-10, and IL-12 (p40) mRNA by LPS was reduced by &gt; 95% in the liver of macrophage-depleted mice, implicating macrophages as the primary producers of these cytokines. Macrophage depletion resulted in a 50 to 75% reduction in TNF-alpha mRNA in the liver. The results from Cl2MBP-liposome-treated mice also suggested that splenic macrophages were the primary producers of LPS-induced IL-1 beta, IL-6, IL-12 (p40), and IL-1 receptor antagonist (IL-1ra) mRNA, but not IL-10 and TNF-alpha mRNA. Mice treated with Cl2MBP-liposomes were more susceptible to ionizing irradiation than control mice, whether or not they were administered a radioprotective dose of LPS. These findings suggest that depletion of liver and splenic macrophages results in a dysregulation of basal and LPS-induced cytokine responses that can be associated with an altered biologic response.
Selective deactivation of human monocyte functions by TGF-beta.
Authors: Warwick-Davies J , Lowrie D B , Cole P J 
Published: January 2023

Abstract
TGF-beta at 1 and 10 ng/ml inhibited H2O2 production and fibronectin adherence by human monocytes. Coculture with anti-TGF-beta Abs or with IFN-gamma, but not with growth hormone, abrogated these effects. Neither viability nor superoxide production were decreased by TGF-beta treatment. TGF-beta appeared to be inhibiting H2O2 production rather than inducing catalase as preincubation in azide was without effect. Also, TGF-beta did not inhibit activity against virulent Mycobacterium tuberculosis. Coculture of monocytes with IFN-gamma + TGF-beta in vitro moderately inhibited the growth of M. tuberculosis when compared with untreated cells. Phagocytosis was not inhibited. Treatment of monocytes with another combination of cytokines, IFN-gamma+ TNF-alpha + vitamin D3, markedly reduced bacterial viability, although this appeared to be due to decreased phagocytosis leading to extracellular death of the bacteria. We conclude that despite suppressing some monocyte functions such as H2O2 production and adherence, TGF-beta, in combination with other cytokines, leaves other antimicrobial functions of the monocyte unaffected or even enhanced.
An alternative splice variant of human IL-4, IL-4 delta 2, inhibits IL-4-stimulated T cell proliferation.
Authors: Atamas S P , Choi J , Yurovsky V V , White B 
Published: January 2023

Abstract
Alternative splicing of mRNA can generate protein isoforms that are preferentially expressed in different tissues or during different states of cell differentiation or activation. Protein isoforms may have different functions. In this study, we cloned, expressed, and tested functional effects of a naturally occurring splice variant of human IL-4, called IL-4 delta 2. In IL-4 delta 2, the second exon of IL-4 is omitted by alternative splicing, with exons 1, 3, and 4 joined in an open reading frame. We found that IL-4 delta 2 RNA is expressed in the PBMC of all donors tested, usually in lower amounts than IL-4 RNA. In contrast, IL-4 delta 2 RNA is expressed in much higher levels than IL-4 RNA in thymocytes and bronchoalveolar lavage cells, suggesting tissue specificity of expression. IL-4 delta 2 cDNA was expressed in yeast. Recombinant human (rh) IL-4 delta 2 was partially purified and found to be glycosylated, with a protein core of 13 to 15 kDa. Unlike rhIL-4, rhIL-4 delta 2 did not act as a costimulator for T cell proliferation. However, rhIL-4 delta 2 inhibited the ability of rhIL-4 to act as a T cell costimulator. Inhibition was independent of glycosylation and was not mediated by toxicity. Iodinated IL-4 delta 2 was found to bind specifically to human PBMC and tumor lines known to express IL-4 receptors. Excess unlabeled IL-4 inhibited cellular binding of labeled IL-4 delta 2. Thus, rhIL-4 delta 2 is a naturally occurring splice variant of IL-4 that is preferentially expressed in the thymus and airways and inhibits function of complete IL-4. The balance between IL-4 and IL-4 delta 2 may be important in the regulation of IL-4 effects.
Structure and expression of murine CD30 and its role in cytokine production.
Authors: Bowen M A , Lee R K , Miragliotta G , Nam S Y , Podack E R 
Published: January 2023

Abstract
Murine CD30 cDNA predicts a protein of 498 amino acids with homology to the TNF receptor family of proteins characterized by repeated cysteine-rich motifs in the extracellular domain. Murine CD30, although homologous to human CD30, has a 90 amino acid gap in an extracellular region that appears to be duplicated in human CD30. Murine CD30 cDNA was shown to be functional through the production of a soluble murine Ig fusion protein (CD30-Ig) that was active in binding to cells that expressed CD30 ligand. CD30-Ig also served as an immunogen for the production of hamster anti-mouse CD30 mAbs, which recognized both CD30 expressed by murine lymphocytes and CD30 expressed by cells transfected with murine CD30 cDNA. CD30 mRNA is highly expressed in the thymus and in activated spleen cells, but not in other tissues tested. In anti-CD3-activated spleen cells, CD30 ligand is expressed primarily by CD4+ T cells, with peak expression at days 1 and 2, whereas CD30 is expressed primarily by CD8+ T cells, with peak expression on days 4 and 5. Stimulation of CD30 by plate-bound anti-CD30 directly signaled for IL-5 but not IFN-gamma production by CD30+ CTL lines. These studies demonstrate that CD30 directs cytokine secretion and suggest that CD30 signaling may be pivotal in the pattern of cytokine production by T cells.
The class II MHC I-Ag7 molecules from non-obese diabetic mice are poor peptide binders.
Authors: Carrasco-Marin E , Shimizu J , Kanagawa O , Unanue E R 
Published: January 2023

Abstract
The class II molecules of the diabetes-prone NOD mice, I-Ag7, showed very limited amounts of stable form when analyzed by SDS-PAGE. We included the analysis of spleen B cells and B lymphoma cells transfected with I-Ag7 genes. Early during bio-synthesis there was invariant chain binding to the alpha beta-chains. Examination of APCs from F1 mice (NOD x C57BL/6) indicated that the same APC expressed high levels of unstable I-Ag7 and normal amounts of stable class II molecules compared with the other haplotype (I-Ab). The half-life of I-Ag7-peptide complexes on the cell surface of APC was significantly shorter than that of other class II haplotypes. Direct biochemical demonstration of peptide interactions with I-Ag7 was difficult to demonstrate. In T cell assays, the immunogenic peptides, including the diabetogenic Ag, were rapidly lost when peptide-pulsed APCs were washed free of peptide. We hypothesize that the weak and unstable peptide-binding property of I-Ag7 molecules does not favor the elimination or inactivation of autoreactive T cells.
Activation of type I protein kinase A during receptor-mediated human T lymphocyte activation.
Authors: Laxminarayana D , Kammer G M 
Published: January 2023

Abstract
The experiments reported herein have characterized the signaling pathway leading to stimulation of type I protein kinase A isozyme (PKA-I) activity during the early events of Ag receptor-mediated T cell activation. Inhibitor studies demonstrated that receptor-initiated activation of nonreceptor protein tyrosine kinases, phosphorylation and activation of phospholipase C-gamma 1, and activation of protein kinase C occur temporally and precede PKA-I activation. Bypass of both the TCR/CD3 complex and IL-1R and direct activation of protein kinase C by a phorbol ester can also activate PKA-I. To confirm that PKA-I activation via the TCR/CD3 complex and IL-1R requires antecedent protein tyrosine kinase-catalyzed phosphorylation of phospholipase C-gamma 1, we used wild-type and CD45-deficient (mutant J45.01) Jurkat T cell lines. Unlike wild-type Jurkat T cells, the absence of CD45 tyrosine phosphatase resulted in the failure of receptor-mediated activation of PKA-I activity and of IL-2 mRNA transcription in the mutant J45.01 Jurkat cell line. In conclusion, our data support the concept that a signal derived from ligand binding to both the TCR/CD3 complex and IL-1R receptor mediates rapid activation of the PKA-I isozyme in primary T lymphocytes by sequential activation of an intracellular pathway comprised of CD45 phosphatase/protein tyrosine kinase/polyphosphoinositide/Ca2+/protein kinase C pathway rather than via the conventional surface receptor/stimulatory G protein system.
Functional dissociation of CD8 alpha's Ig homologue and connecting peptide domains.
Authors: Meyerson H J , Huang J H , Fayen J D , Tsao H M , Getty R R , Greenspan N S , Tykocinski M L 
Published: January 2023

Abstract
The contribution of the CD8 alpha.IgV homologue domain to class I MHC binding was evaluated using a series of chimeric human CD8 alpha:Fc polypeptides incorporating alternative CD8 alpha extracellular domain components. Using a nonisotopic cellfree physical binding assay, those Fc chimeras encompassing the CD8 alpha.IgV homologue domain only (dissociated from the 48-amino acid CD8 alpha connecting peptide) were shown to retain the capacity of the complete CD8 alpha extracellular domain to bind to a recombinant soluble class I MHC alpha 3 domain unit or to intact class I MHC. The specificity of the CD8 alpha:class I MHC alpha 3 domain interaction was verified by mAb and soluble polypeptide blocking experiments. Furthermore, co-precipitation of an Fc chimera incorporating only the CD8 alpha.IgV homologue domain and a recombinant soluble class I MHC alpha 3 domain unit was accomplished. In addition, a glycosylphosphatidylinositol (GPI)-modified variant of the CD8 alpha.IgV homologue domain was generated via chimerization with the GPI signal sequence from decay-accelerating factor. GPI anchorage for this truncated CD8 alpha polypeptide was verified, and its capacity to promote intercellular adhesion through class I MHC binding was shown in a cell:cell binding assay. The findings indicate that the CD8 alpha.IgV homologue domain acts as an independent structural unit when dissociated from the CD8 alpha connecting peptide, and in so doing retains class I MHC binding capacity. This further establishes the principle that Ig superfamily domains from receptor:counter-receptor pairs can interact with each other as isolated units, providing an experimental path for tailoring therapeutically useful IgSF protein derivatives.
A powerful new technique for isolating genes encoding cell surface antigens using retroviral expression cloning.
Authors: Zannettino A C , Rayner J R , Ashman L K , Gonda T J , Simmons P J 
Published: January 2023

Abstract
cDNA expression cloning using retroviral vectors provides a means of stably introducing genes into target cells at efficiencies that surpass those achieved by transfection. Furthermore, retroviral vectors allow for the introduction and expression of complex cDNA libraries in a wide range of cell types, including cells of hemopoietic origin. Here we report a novel method for rapidly isolating genes encoding cell surface molecules (CSM) from a human bone marrow stromal cell cDNA library constructed in the retroviral vector, pRUFneo. With a newly described, highly efficient selection strategy using mAb and Ab-coated magnetic beads, we have successfully isolated six cDNA encoding previously defined CSM, including beta 1 integrin and endoglin. Moreover, we have used this approach to define the gene and hence the CSM identified by three previously unclustered mAb. These results confirm previous studies demonstrating the general utility of retroviral cDNA libraries and further extend their use to the expression cloning of cDNA encoding CSM.
Down-regulation of T lymphocyte activation in vitro and in vivo induced by glycoinositolphospholipids from Trypanosoma cruzi. Assignment of the T cell-suppressive determinant to the ceramide domain.
Authors: Gomes N A , Previato J O , Zingales B , Mendonça-Previato L , DosReis G A 
Published: January 2023

Abstract
The major surface glycoinositolphospholipid (GIPL) from Trypanosoma cruzi was purified and assessed in mouse T cell function assays. Purified GIPLs from T. cruzi strains Y and G, but not from a plant trypanosomatid (Phytomonas serpens), markedly blocked in vitro CD4+ and CD8+ T cell mitogenesis induced by bacterial superantigen and anti-TCR;CD3 Abs. Secretion of IL-2, but not of IL-4, bioactivity, was reduced by GIPLs. T. cruzi, but not P. serpens, GIPL also blocked recall cellular responses to T. cruiz. GIPLs from T. cruzi, but not from P. serpens, blocked in vivo regional lymph node T cell activation induced by anti-CD3 mAb. Blockage led to loss of IL-2 responsiveness, with inhibition of CD25 expression on both CD4+ and CD8+ subsets. Isolated phosphoinositol oligosaccharides from GIPLs had no effect on in vitro CD4+ T cell mitogenesis. Isolated ceramide from T. cruzi GIPLs contained mainly N-lignoceroyldihydrosphingosine and blocked CD4+ T cell activation in vitro with the same potency as the intact GIPL. Standard N-palmitoylsphingosine, but not N-palmitoyldihydrosphingosine, blocked CD4+ T cell mitogenesis. A longer fatty acid chain, such as in standard N-lignoceroyldihydrosphingosine, or in the natural trypanosomal GIPL-derived ceramide, however, conferred full inhibitory effects on CD4+ T cells. These results demonstrate that T. cruzi GIPL has T cell immunomodulatory activity in vitro and in vivo, and that this novel activity maps to the ceramide domain. These findings could have implications for immunologic disturbances induced in the host by the causative agent of Chagas' disease.
Production of nitric oxide (NO) is not essential for protection against acute Toxoplasma gondii infection in IRF-1-/- mice.
Authors: Khan I A , Matsuura T , Fonseka S , Kasper L H 
Published: January 2023

Abstract
Production of nitric oxide (NO) by macrophages is important for the killing of intracellular pathogens. IFN-gamma and LPS stimulate NO production by transcriptional up-regulation of inducible nitric oxide synthetase (iNOS). In the present study we used mice with a targeted disruption of the IFN regulatory factor-1 gene (IRF-1-/-) to investigate the importance of NO in the host immune response against Toxoplasma gondii, a major cause of infection in newborns and those with AIDS. IRF-1-/- mice were more susceptible to acute Toxoplasma infection, and treatment with either exogenous IFN-gamma or in vivo neutralization of endogenous IFN-gamma had little effect on their susceptibility to infection. However, administration of exogenous IL-12 was able to prolong survival even when IFN-gamma was depleted. An in vivo depletion study suggested that the mechanism of this protective response is mediated in part by CD4+ T cells. The administration of IL-12 could not overcome the inhibition of lymphoproliferative response in T. gondii-infected mice and treatment with N-monomethyl-L-arginine (L-NMMA), a nitric oxide synthase (iNOS) antagonist in vitro was unable to reverse the immunosuppression. In response to Toxoplasma infection, splenocytes from IRF-1-/- mice exhibited increased production of IL-10 as well as a 30-fold increase in its message expression. These studies indicate that NO may not be essential for host immunity to the parasite, and moreover that IL-12 appears to induce an IFN-gamma-independent mechanism of protection against this opportunistic pathogen.