bluuebunny/crossref_metadata_2025_split huggingface dataset:
Overlapping epitopes encompassing a point mutation (12 Gly → Arg) in p21 ras can be recognized by HLA‐DR, ‐DP and ‐DQ restricted T cells
Authors: Fossum Beate , Gedde‐Dahl Tobias , Hansen Torbjern , Eriksen Jon Amund , And Erik Thorsby , Gaudernack Gustav 
Published: March 2007

AbstractMutations in ras genes which result in transforming gene products carrying amino acid substitutions in position 12, 13 or 61 are common in human cancer. Peptides encompassing these mutations in ras are shown to be immunogenic in both mice and humans. The potential usefulness of such peptides in cancer therapy, depends on their ability to bind to HLA molecules. We therefore stimulated T cells from healthy donors with mutated ras‐derived peptides. By repeated in vitro stimulation of peripheral blood mononuclear cells, several T cells clones could be generated which recognized a p21 ras derived peptide carrying a position 12 Gly → Arg substitution. This peptide (1–25, 12 Arg) could be specifically recognized by T cells restricted by either HLA‐DQ7 or ‐DP3. Previously, we showed that this peptide is also recognized by a T cell clone restricted by HLA‐DR2. The core region of the peptide was determined to span positions 9–16 for all three HLA restriction elements, and accordingly contains the mutational hot spots in position 12 and 13. The observation that the mutant 1–25, 12 Arg ras‐derived peptide may contain a promiscuous epitope encompassing the Gly → Arg mutation in position 12 indicates that lack of peptide presentation by given HLA molecules may not be a major constraint in responsiveness against ras mutations.
Number of interleukin‐4‐ and interferon‐γ‐secreting human T cells reactive with tetanus toxoid and the mycobacterial antigen PPD or phytohemagglutinin: distinct response profiles depending on the type of antigen used for activation
Authors: Elghazali Gehad E. B. , Paulie Staffan , Andersson Gudrun , Hansson Yngve , Holmquist Göran , Sun Jia‐Bin , Olsson Tomas , Ekre Hans Peter , Troye‐Blomberg Marita 
Published: March 2007

AbstractThe enzyme‐linked immunospot (ELISPOT) assay has been proven to be an efficient and sensitive method for the enumeration of single cells secreting antibodies or cytokines. Here we have used this method to determine the number of interleukin‐4 (IL‐4)‐ and interferon‐γ (IFN‐γ)‐producing cells in in vitro secondary responses to tetanus toxoid (TT) and the mycobacterial antigen (purified protein derivative; PPD) or the mitogen phytohemagglutinin (PHA). PHA‐induced IL‐4 and IFN‐γ secretion was well correlated suggesting polyclonal activation of cells. This was not the case with the specific antigens, where PPD preferentially induced IFN‐γ‐ and very few IL‐4‐producing cells, while TT‐induced both IL‐4 and IFN‐γ. These differences are probably a reflection of the types of immunity the two antigens induce, mycobacteria preferentially inducing a cell‐mediated T helper type 1 (Th 1) type of immunity, while immunity to tetanus is an antibody‐dependent, Th 2 type of response.In individuals recently boosted with TT, a significant increase in both IL‐4‐ and IFN‐γ‐producing cells in response to TT was seen at day 7 after boost, followed by decline. This was in contrast to what was seen in response to PPD where an increase of IFN‐γ‐producing cells after the TT boost at day 7 persisted for at least 14 days. These results suggest that after an in vivo boost both antigen‐specific and nonspecific T cells are activated and that antigen‐specific cells home to other organs and therefore may be difficult to demonstrate in the circulation. Our data show that the ELISPOT assay is a powerful tool for determining the frequency of cells secreting cytokines. The assay has several advantages over other assays since it is sensitive, measures the number of actually secreting cells, and avoids the problems of binding of cytokines to their cell‐bound or soluble receptors.
An endogenously synthesized decamer peptide efficiently primes cytotoxic T cells specific for the HIV‐1 envelope glycoprotein
Authors: Bergmann Cornelia , Stohlmann Stephen A. , McMillan Minnie 
Published: March 2007

AbstractThe immunodominant H‐2Dd‐restricted cytotoxic T lymphocyte (CTL) response to the HIV‐1 gp160 envelope glycoprotein maps to a single determinant in the V3 loop, designated p18. Using a series of peptides synthesized on pins we have determined that the minimal core sequence of this determinant required for CTL recognition comprises 8 amino acids (residues 320‐327). However, 9mer and l0mer peptides containing this core sequence were more effective than the 8mer peptide at sensitizing Dd‐expressing target cells. To analyze the antigenicity of endogenously synthesized p18, minigenes encoding a 10‐amino acid determinant (residues 318‐327) and a 67‐amino acid peptide (residues 281‐348; containing the V3 loop) were expressed using vaccinia virus (Vac) recombinants. Both peptides were as effective as wild‐type gpl60 in their ability to sensitize target cells for lysis by gpl60‐specific CTL. Immunization of BALB/c mice with Vac recombinants encoding both gp160 peptides elicited gp160‐specific CTL. These data demonstrate that both the V3 loop itself and a 10‐residue epitope are sufficient to prime CTL in vivo and strongly support the potential use of minigene‐encoded CTL epitopes for recombinant vaccines designed to induce protective T cell‐mediated immunity against HIV‐1.
Characterization of two new CD18 alleles causing severe leukocyte adhesion deficiency
Authors: Rodríguez Cristina Löpez , Nueda Arsenio , Grospierre Barbara , Fischer Alain , Springer Timothy A. , Corbi Angel L. 
Published: March 2007

AbstractLeukocyte adhesion deficiency (LAD) is an autosomal recessive disease caused by heterogeneous mutations within the gene encoding the common β subunit (CD18) of the three leukocyte integrins LFA‐1 (CD11a/CD18), Mac‐1 (CD11b/CD18), and pl50,95 (CD11c/CD18). Based on the level of expression of CD18 on patient leukocytes, two phenotypes of LAD have been defined (severe and moderate) which correlate with the severity of the disease. We have investigated the molecular basis of the disease in two unrelated severe patients (HS and ZJO). Both patients share a complete absence of CD18 protein precursor and cell surface expression, but they differ in the level of CD18 mRNA, which is normal in HS and undetectable by Northern blot in ZJO. Determination of the primary structure of the patient HS CD18 mRNA revealed a 10‐base pair deletion between nucleotides 190‐200 (CD 18 exon 3), which eliminates residues 41–43 and causes a frameshift into a premature termination codon 17 base pairs downstream from the deleted region. The 10‐base pair frameshift deletion maps to a region of the CD18 gene where aberrant mRNA processing has been detected in HS and two other unrelated LAD patients. In the ZJO patient, amplification of lymphoblast CD 18 mRNA demonstrated the presence of a non‐sense mutation in the third nucleotide of the triplet encoding Cys534 (TGC → TGA), within exon 12. Both genetic abnormalities were also detected at the genomic level, and affect the restriction pattern of their corresponding genes, thus enabling the detection of the mutant alleles among healthy heterozygous alleles in family studies. The identification of two new LAD CD18 alleles, either carrying a non‐sense mutation (ZJO) or a partial gene deletion (HS), further illustrates the heterogeneity of the genetic alterations in LAD.
ICAM‐3, the third LFA‐1 counterreceptor, is a co‐stimulatory molecule for both resting and activated T lymphocytes
Authors: Hernandez‐Caselles Trinidad , Rubio Gonzalo , Campanero Miguel R. , del Pozo Miguel Angel , Muro M. , Sanchez‐Madrid Francisco , Aparicio Pedro 
Published: March 2007

AbstractOptimal activation of human T cells mediated by ligation of CD3/T cell receptor (TcR) complex requires co‐stimulatory signals. These can be provided by the adhesive interaction between receptor molecules on T cells and their counter‐receptors on antigen‐presenting cells. Soluble ICAM‐3, anti‐ICAM‐3 and anti‐CD3 mAb were utilized to address the role of the ICAM‐3/LFA‐1 pathway in TcR/CD3‐dependent or ‐independent T cell activation. Immunoaffinity‐purified ICAM‐3 co‐immobilized with suboptimal concentrations of anti‐CD3 monoclonal antibody (mAb) stimulated T lymphocytes as monitored by the expression of the lymphocyte activation antigens CD25 and CD69. The mechanism underlaying this activation appear to involve the interaction of ICAM‐3 with a β2 integrin, likely to be LFA‐1, since mAb to the CD18 chain completely inhibited T cell activation. Similar experiments demonstrated that anti‐ICAM‐3 mAb were able to co‐stimulate both resting (cord blood) and activated (T cell clones) T lymphocytes. On the contrary, anti‐ICAM‐1 mAb were only co‐stimulatory for CD25 expression on activated but not on resting T cells. In addition, we have found that some γδ T cell clones bearing the Vδ1 segment were activated by direct mAb engagement of ICAM‐3 in the absence of TcR/CD3 occupancy. Furthermore, immobilized anti‐ICAM‐3 mAb also induced development of dentritic processes. In conclusion, our data suggest that ICAM‐3 on the surface of both T cells and antigen‐presenting cells plays an essential role in the initiation of the immune response.
Schistosoma mansoni circulating anodic antigen but not circulating cathodic antigen interacts with complement component C1q
Authors: van Dam Govert J. , Seino Jin , Rotmans J. Peter , Daha Mohamed R. , Deelder André M. 
Published: March 2007

AbstractAdult schistosome parasites, living in the blood vessels of their mammalian hosts, protect themselves against immune damage in a variety of ways. In addition to the tegument, the intestinal epithelium of the blood‐feeding worms is permanently exposed to both the innate and the acquired immune system. In this study, we investigated whether the Schistosoma gut‐associated antigens CAA and CCA (circulating anodic antigen and circulating cathodic antigen, respectively), which are excreted in relatively large quantities into the host's circulation, might play a role in evading complement attack. Of several complement components tested, only purified C1q showed significant binding to CAA, a negatively charged highly glycosylated glycoprotein. CCA, also highly glycosylated, but neutral or slightly positively charged, did not bind to C1q. CAA bound only to the collagen‐like stalks of C1q and not to the globular heads. No detectable interaction of CAA with precursor human CI was found and CAA did not induce activation of CI in whole human serum as assessed by consumption of hemolytic C4 activity. Also CAA could not induce activation of precursor CI in vitro. These results suggest that CAA behaves like a receptor for C1q, and might be involved in protecting the vulnerable schistosome gut against complement‐mediated attack.
Signaling of programmed cell death induction in WEHI‐231 B lymphoma cells
Authors: Hibner Urszula , Benhamou Laure E. , Haury Matthias , Cazenave Pierre‐André , Sarthou Pierre 
Published: March 2007

AbstractThe murine WEHI‐231 B lymphoma is highly sensitive to membrane immunoglobulin ligation which leads to programmed cell death (PCD) in this cell line. To study the molecular pathways involved in PCD induction in these cells, we derived two variants of WEHI‐231 resistant to anti‐Ig treatment. The level of bcl‐2 mRNA was identical in the wild type and the variants, either untreated or anti‐Ig treated, suggesting that PCD is not under the control of bcl‐2 in WEHI‐231 cells. In contrast, c‐myc gene expression was markedly different in the wild type and the variants, both in the unstimulated and anti‐Ig‐stimulated state. Our findings are interpreted in the context of the dual capacity of c‐myc to promote cell growth or cell death, in conjunction with other growth regulatory signals.
Cross‐linking of CD59 and of other glycosyl phosphatidylinositol‐anchored molecules on neutrophils triggers cell activation via tyrosine kinase
Authors: Morgan B. Paul , van den Berg Carmen W. , Davies Eryl V. , Hallett Maurice B. , Horejsi Vaclav 
Published: March 2007

AbstractMany membrane proteins are attached via a glycosyl phosphatidylinositol (GPI) anchor. Proteins anchored in this way make no direct contact with the interior of the cell, therefore a role in signaling or activation would seem unlikely. Nevertheless, cross‐linking of GPI‐anchored proteins on human and murine T lymphocytes has been shown to cause calcium transients and cell activation. Our studies address the non‐lethal events caused by the membrane attack complex of complement, which include release of Ca2+ from intracellular stores, and have suggested that the GPI‐anchored complement inhibitor CD59 may be involved in signaling these events. We here report that cross‐linking of CD59 on human neutrophils using specific monoclonal antibody and second antibody caused a rapid increase in intracellular free Ca2+ concentration (Ca2+ transient) due to release of Ca2+ from stores and also caused neutrophil oxidase activation. All antibodies against CD59 tested were effective and cross‐linking of any other GPI‐anchored protein expressed on neutrophils also initiated an increase in intracellular free Ca2+ concentration, whereas cross‐linking of transmembrane proteins caused little or no response. A tyrosine kinase‐dependent activation pathway was indicated by the demonstration of tyrosine phosphorylation on cross‐linking and by blocking of the Ca2+ transient with the tyrosine kinase inhibitor herbimycin.
Patterns of major histocompatibility complex class II expression on T cell subsets in different immunological compartments 1. Expression on resting T cells
Authors: Dutia Bernadette M. , McConnell Ian , Bird Kay , Keating Paula , Hopkins John 
Published: March 2007

AbstractIn this study we have investigated the expression of major histocompatibility complex (MHC) class II molecules on T cells from various lymphoid compartments in the sheep. Monoclonal antibodies which react specifically with sheep MHC class II molecules homologous to the human DQ and DR molecules have been characterized. These antibodies have been used, together with the monoclonal antibodies specific for sheep CD4‐, CD8‐ and T19‐positiveT cells, to quantitate DQ and DR expression on T cell subsets in adult and fetal peripheral blood, afferent lymph, lymph node and efferent lymph. The results show that expression of class II by T cells depends on the age of the animal and the physiological location of the T cell. In fetal blood there is no expression of class II on CD8+ or T19+ cells and very low expression on CD4+ T cells. In adult peripheral blood and efferent lymph a significant proportion of cells express DR but not DQ. A very different situation is found in afferent lymph and the peripheral lymph node: in afferent lymph the majority of T cells in all three subsets express both DQ and DR molecules; in the lymph node over 50% of T cells express DR and 30 % are DQ+. These results suggest that within all T cell subsets there is a progression from DQ− DR− to DQ−DR+ and DQ+DR+ which correlates with physiological stages of T cell differentiation in vivo.
Major histocompatibility complex regulation of interleukin‐5 production in the mouse
Authors: Dieli Francesco , Sireci Guido , Lio Domenico , Bonanno Cesira T. , Salerno Alfredo 
Published: March 2007

AbstractLymph node cells of CBA (H‐2k), but not of BALB/c (H‐2d) mice immunized epicutaneously with picryl chloryde secrete interleukin (IL)‐5 when stimulated with the specific antigen in vitro. The low IL‐5 production in BALB/c mice persists when either picryl chloride or the unrelated antigen oxazolone are used, when the amount of antigen in vitro is varied and when a secondary response is studied. The difference in IL‐5 production maps to the major histocompatibility complex (MHC) in the congenic BALB/b, BALB/c and BALB/k mice. Furthermore, lymph node cells from (k × d) F1 mice produce IL‐5 when stimulated by antigen presented on H‐2k but not on H‐2d antigen‐presenting cells.Finally, the low IL‐5 production in vitro in BALB/c mice is correlated with low picryl‐specific IgA levels in vivo, which otherwise are ten times greater in CBA and BALB/k mice. The influence of MHC on IL‐5 production and IgA secretion in the mouse might be a possible basis for the association of MHC with IgA deficiency in humans.
The thymus‐independent antigen α(1–3) dextran elicits proliferation of precursors for specific IgM antibody‐producing cells (memory cells), which are revealed by LPS stimulation in soft agar cultures and detected by immunoblot
Authors: Kolb Cornelia , Fuchs Bergund , Weiler Eberhardt 
Published: March 2007

AbstractSingle antibody‐forming cells (AFC) specific for α(l‐3) dextran (Dex) from i.p.‐immunized BALB/c mice were enumerated in soft agar cultures by blotting on antigen‐precoated membranes and subsequent staining via enzyme‐coupled anti‐IgM antibodies. Short cultures (2 h) revealed AFC as harvested ex vivo, while in long‐term cultures (4 days), in the presence of lipopolysaccharide (LPS) as B cell mitogen, cells or colonies developed by differentiation in vitro. Whereas the spleen contained most AFC ex vivo in a sharp‐peak response at 4 and 5 days after i.p. injection of Dex in aqueous solution, peritoneal exudate cells (PEC) contained only very few AFC. However, the same PEC population developed Dex‐specific cells or colonies after 4 days of culture. The isotype of antibodies was IgM. The frequency of these Dex‐specific LPS‐inducible precursor cells rose exponentially in the course of the immune response to a broad plateau and was still, 11 weeks after Dex injection, approximately 40‐fold higher than in non‐immunized mice.Since these cells increased in frequency after antigen injection, and since they could not be detected as AFC during 2 h ex vivo, they were regarded as memory cells. They seemed to be arrested in vivo, but could be induced to differentiation and/or proliferation in vitro. Although these cells had the functional characteristics of memory cells as defined above, they produced anti‐Dex antibodies of IgM isotype. Their population might be critical for the protection of the peritoneal cavity against microbial invasion from the intestines, and it may be significant in this context that we could evoke a peritoneal memory cell response only when antigen was injected intraperitoneally, but not intravenously. In athymic BALB/c‐nu/nu mice only few of these Dex‐specific memory cells were found. It is possible that T cells exert a regulatory influence on this pathway of differentiation.
Differences in the requirement of antigen‐presenting cells for long‐term growth among cytomegalovirus‐specific Th clonotypes
Authors: Santamaria Pere , Lewis Cinthia , Barbosa Jose J. 
Published: March 2007

AbstractFunctional and molecular studies of in vivo‐activated T lymphocytes involved in normal and abnormal immune responses, i. e., cells infiltrating tissues affected by autoimmune processes, require their previous in vitro expansion. Problems such as unavailability of specific antigen(s) (Ag) and/or the requirement of large amounts of autologous peripheral blood mononuclear cells (PBMC) as feeders have prompted the development of alternative expansion methods that circumvent the use of antigen‐presenting cells (APC) and/or Ag. We have previously shown that cytomegalovirus (CMV)‐specific Tcell lines and clones can be efficiently propagated in long‐term cultures by stimulation with agonistic monoclonal antibodies (mAb) coated onto polystyrene particles in the absence of APC. However, this and other stimulation protocols may skew the repertoire of clonotypes that proliferate in response to nominal Ag and APC. Here we show that polyclonal populations of CMV‐primed and interleukin‐2 (IL‐2)‐stimulated PBMC undergo the same clonotypic selection when induced to grow both by continuous stimulation with CMV and an anti‐CD3 mAb presented by APC. This selection, reproduced in three independent expansion experiments, involved the dominant growth of two CMV‐specific, IL‐2‐secreting CD4+ clonotypes sharing Jα, Jβ, Vα and Vβ genes and highly homologous T cell receptor (TcR) junctional sequences. The dominant growth of these 2 clonotypes required a direct Tcell/APC interaction since when coated onto polystyrene particles the same mAb induced the selective expansion of another IL‐2‐secreting CD4+ CMV‐specific clonotype expressing a different, yet homologous, TcR heterodimer (used same Vα and Vβ genes), which was underrepresented before expansion (5 vs. 58%). Tcell clones belonging to the subdominant clonotype proliferated significantly faster in response to stimulation with anti‐CD3 mAb coated onto beads than in response to stimulation with CMV or anti‐CD3 mAb presented by APC, possibly due to long‐term expansion without APC or antigen. In contrast, neither the dominant clonotypes nor unprimed T cells were able to undergo CD3‐mediated expansion in the absence of APC. We conclude that quantitative differences in growth competency among nominal Ag‐activated T‐helper (Th) clonotypes in response to antigenic stimulation can be reproduced by stimulation through the TcR in the absence of TcR occupancy but only in the presence of APC and that certain clonotypes do not require APC for long‐term growth in vitro. These data have practical implications for the isolation and repertoire characterization of in vivo‐activated T cells from tissues affected by inflammatory, i.e. autoimmune, phenomena.
Selective coupling of the T cell antigen receptor to phosphoinositide‐derived diacylglycerol production in HPB‐ALL T cells correlates with CD45‐regulated p59fyn activity
Authors: Biffen Mark , Shiroo Masahiro , Alexander Denis R. 
Published: March 2007

AbstractIn HPB‐ALL T‐cells the p59fyn tyrosine kinase is regulated by the CD45 phosphotyrosine phosphatase and plays a critical role in coupling the T cell receptor (TCR) to the generation of intracellular signals which include diacylglycerol (DAG) production and protein kinase C activation. The aim of this study was to determine the phospholipid pools from which the DAG is generated and to identify which phospholipase activities are regulated by the TCR. When CD45+cells were pre‐labeled with [3H] arachidonic acid, CD3‐antigen cross‐linking stimulated negligible increases in both [3H]DAG and [3H] phosphatidic acid (PA). However, CD3 monoclonal antibody (mAb) induced an increase of 300 % in [3H]PA when the cells were permeabilized with streptolysin‐O, and this correlated with increased levels of protein tyrosine phosphorylation. Stimulation of [3H] PA production upon CD3 cross‐linking was 77 % lower in permeabilized CD45− cells than in CD45+ cells, consistent with the reduced activity of p59fyn in CD45− cells. The stimulated production of PA was not mediated by activation of phospholipase D (PLD), although the presence of a G‐protein‐regulated PLD activity was established. The CD3‐induced increase in total inositol phosphates (InsP) in permeabilized cells was similar to the stimulated production of [3H] PA production in both CD45+ and CD45− cells. Dose‐response curves for InsP and PA production triggered by CD3 mAb were super‐imposable and the production of InsP and PA over a range of Ca2+ concentrations was comparable. Differential labeling of phospholipids with 3H‐labeled fatty acids revealed that CD3‐induced PA production reflected incorporation of label into the phosphatidylinositol pool. Our data suggest that in HPB‐ALL cells the production of DAG following CD3‐antigen cross‐linking can be fully accounted for by the selective coupling of the TCR to breakdown of phosphatidylinositol‐(4,5)‐bisphosphate as the result of phospholipase Cγ1 activation. This event correlates with the activity of the CD45‐regulated TCR‐associated tyrosine kinase, p59fyn.