bluuebunny/crossref_metadata_2025_split huggingface dataset:
A monoclonal antibody reactive with a glycophosphatidylinositol‐anchored molecule on T cells defines CD4+ T cell subsets
Authors: Nagata Norikazu , Taketani Shigeru , Adachi Yasushi , Hosaka Naoki , Miyashima Shigeo , Tokunaga Rikio , Ikehara Susumu 
Published: March 2007

AbstractA hybridoma, 25T3 (IgM, χ), was established from MRL/+ mice immunized with an autoreactive T cell line (1/+T1). The antigenicity of the antigen recognized by hybridoma 25T3 (25T3‐Ag) expressed on thymic and splenic cells was abolished by treatment with phosphatidylinositol‐specific phospholipase C, showing that 25T3‐Ag is a glycophosphatdidylinositol‐anchored Ag. 25T3‐Ag was expressed on approximately 90% of thymocytes. Double‐negative, double‐positive and CD8 single‐positive cells were highly positive for the expression of 25T3‐Ag, whereas CD4 single‐positive cells were weakly positive (approximately 40 %) or negative (approximately 60%). In the spleen, only CD3+ cells (and not B220+ nor Mac‐1+ cells) reacted with 25T3 monoclonal antibody (mAb), indicating that 25T3 mAb is specific for T cells. The majority of splenic CD8+ T cells were positive for the expression of 25T3‐Ag, although the intensity was weaker than that of thymocytes. In contrast, splenic CD4+ T cells were divided into negative (60‐70%) and positive (30‐40%) populations. Similar staining profiles were observed in BALB/c, C57BL/6, C3H/HeN and AKR/J mice. When BALB/c CD4+ T cell subsets were sorted and cultured with irradiated (25 Gy) antigen‐presenting cells, stimulation with immobilized anti‐CD3 mAb for 2 days resulted in CD4+25T3+ cells secreting more interleukin‐2 and less interleukin‐4 than did CD4+25T3− subsets, although the proliferative responses of the cells on day 2 of culture were similar. This suggests that CD4+ T cells can be divided into two populations and relatively defined as T helper 1 and T helper 2 cells using this 25T3 mAb. Immunoprecipitation and SDS‐PAGE revealed that 25T3‐Ag was approximately 70 kDa. These findings are discussed in relation to CD4+ T cell subsets.
Clonal deletion as direct consequence of an in vivo T cell response to bacterial superantigen
Authors: Wahl Claudia , Miethke Thomas , Heeg Klaus , Wagner Hermann 
Published: March 2007

AbstractTo date clonal deletion of peripheral mature T cells is restricted to in vivo model systems characterized by prolonged exposure of mice to antigens and clonal T cell expansion preceding clonal deletion. Here we describe that upon challenge of mice with the superantigen staphylococcal enterotoxin B two immediate events become imposed on ligand‐reactive Vβ8+ T cells in lymph node cells draining the local site of injection. First, and within hours Vβ selective clonal deletion is initiated via an apoptotic process. Second, the remaining Vβ8+ T cells first develop a profound state of ligand‐specific unresponsiveness and subsequently initiate clonal in vivo growth. It is suggested that the dichotomy of events observed reflects a direct consequence of T cell receptor occupancy in the context of inappropriate signalling.
Identification of peptide sequences that potentially trigger HLA‐A2.1‐restricted cytotoxic T lymphocytes
Authors: Nijman Hans W. , Houbiers Jos G. A. , Vierboom Michel P. M. , van der Burg Sjoerd H. , Drijfhout Jan W. , D'Amaro Joe , Kenemans Peter , Melief Cornelis J. M. , Kast W. Martin 
Published: March 2007

AbstractWe used the human processing defective cell line 174CEM.T2 (T2) to identify potential cytotoxic T lymphocyte (CTL) epitopes of human proteins. Exogenously added peptides can increase the number of properly folded HLA‐A2.1 molecules on the cell surface of T2 cells, as shown by immunofluorescence measurements using the mouse monoclonal antibody BB7.2 (anti‐HLA‐A2.1) and fluorescein isothiocyanate‐labeled goat anti‐mouse F(ab')2 antibody. The peptides were selected on the basis of a computer score derived from the recently described HLA‐A2.1 specific motif. Analysis of the influenza matrix protein showed that 15 out of 35 high‐scoring peptides up‐regulate the expression of HLA‐A2.1 molecules on theT2 cell surface. The combination of the computer scoring program and an immunofluorescence‐based peptide binding assay allows rapid detection of potential CTL target peptides.
Modulation of interferon‐γ receptor during human T lymphocyte alloactivation
Authors: Novelli Francesco , Giovarelli Mirella , Gentz Reiner , Zucca Mario , Pierro Francesco Di , Garotta Gianni , Forni Guido 
Published: March 2007

AbstractPrevious work has shown that neutralization of physiologically secreted interferon(IFN)‐γ or blockade of its receptor during T lymphocyte activation inhibits both proliferation and cytotoxic T lymphocyte generation, suggesting that IFN‐γ plays a crucial role in T lymphocyte induction and differentiation. In this study, the kinetics of the surface expression of the 90‐kDa IFN‐γ receptor (IFN‐γR) was followed during human mixed lymphocyte reaction (MLR) to alloantigens. IFN‐γR mRNA is constitutively expressed on resting peripheral blood lymphocytes emerging from nylon wood column (NW‐PBL) and its expression increases two‐ to threefold on alloactivated NW‐PBL. IFN‐γR protein is poorly expressed on the membrane of resting CD3+ cells, but up‐modulates after 3‐day MLR and sharply down‐modulates at day 6. Both the p55 and the p75 chains of interleukin‐2 receptor (IL‐2R) were shown to up‐modulate in parallel with IFN‐γR, whereas they were still highly expressed at day 6. After alloactivation, IFN‐γ and IL‐2 secretion starts at 24 h, peaks at day 3 and decreases just when IFN‐γR and IL‐2R begin to up‐modulate. Proliferation peaks at day 6. Lastly, stimulation with distinct cell populations showed that the intensity of lymphocyte proliferation, IFN‐γR membrane up‐modulation, and IFN‐γ and IL‐2 secretion are regulated in a parallel manner, thus suggesting that they are interrelated. Taken as whole these results demonstrate that increased expression of IFN‐γR on T lymphocytes can be a critical event during their activation, and strongly support the hypothesis that IFN‐γ/IFN‐γR interaction provides a signal for its progression.
A pattern search method for putative anchor residues in T cell epitopes
Authors: Hobohm Uwe , Meyerhans Andreas 
Published: March 2007

AbstractThe binding affinity between an antigenic peptide and its particular major histocompatibility complex (MHC) molecule seems to be largely determined by only a few residues. These residues have been called “anchors” because of their property of fitting into “pockets” inside the groove of the MHC molecule. To predict natural antigenic epitopes within a longer sequence, it therefore appears to be important to know the motif or pattern describing the anchors, i.e. the anchors amino acid residue preference and the distance between anchor residues.A large set of MHC class I‐restricted peptides has been described. Peptide sequences vary in length and lack an obvious common sequence motif. For a list of peptides belonging to one type of MHC class I molecule, we describe a method to find the most prominent sequence motif with at least two anchor residues. Briefly, antigenic sequences are aligned, and two anchor positions are searched for, where all anchor residues share a high similarity. The alignments are scored according to the similarity of their anchor residues. We show that the motifs predicted for the MHC alleles A2.1, B27, Kb, Kd, Db are in substantial agreement with experimental data. We derive binding motifs for the MHC class I alleles HLA‐A1, All, B8, B14, H‐2Ld and for the MHC class II alleles I‐Ab and I‐As. In some cases, higher scores were obtained by allowing a slight variation in the number of residues between anchors. Therefore, we support the view that the length of epitopes belonging to a particular class I MHC is not uniform.This method can be used to predict the natural short epitope inside longer antigenic peptides and to predict the epitopes anchor residues. Anchor motifs can be used to search for antigenic regions in sequences of infectious viruses, bacteria and parasites.
Systematic study of human αβ T cell receptor V segments shows allelic variations resulting in a large number of distinct T cell receptor haplotypes
Authors: Cornélis François , Pile Kevin , Loveridge Jason , Moss Paul , Harding Rosalind , Julier Cécile , Bell John 
Published: March 2007

AbstractThe variation of the αβ T cell receptor (TCR) results mainly from rearrangements of germ‐line V, D and J elements combined with the processes of N‐ and P‐region addition. In addition to this extensive diversity, diallelic polymorphism is also recognized in V regions of β loci. Four such polymorphisms have previously been defined, but the full extent of such variation has not yet been established. To investigate allelic polymorphism, we used a strategy based on V locus‐specific polymerase chain reaction and single‐strand conformation polymorphisms. Studying the two Vβ 2 loci and the Vα8.1 locus, we found that all exhibited a coding polymorphism. One of the Vβ 2 loci proved to be the first multiallele segment to be recognized, with three common variants. The second Vβ 2 locus, for which none of the two alleles has been identified in cDNA, appeared in fact to be a Vβ orphon, in abnormal location on the chromosome 9. A yeast artificial chromosome containing part of the TCRB locus allowed us to place the first Vβ 2 segment on the known map to define haplotypes with two other polymorphic segments: Vβ 1 and Vβ 6.7. Multiple distinct haplotypes result from combinations between these polymorphic loci, showing that Vβ regions are highly variable between individuals. Two alleles exist at the Vα8.1 segment and both are expressed. This represents the first example of a frequent coding polymorphism for TCRA gene. The distribution of allele frequencies for these segments suggest the action of balancing selection. These data add a further dimension to TCR polymorphism and suggest new candidates to explore TCR‐encoded susceptibility to autoimmune diseases.
Exon skipping without splice site mutation accounting for abnormal immunoglobulin chains in nonsecretory human myeloma
Authors: Cogné Michel , Guglielmi Paul 
Published: March 2007

AbstractThe proliferating plasma cells of patient COM with nonsecretory myeloma synthesized truncated 42 kDa γ1 chains made of a complete constant region but devoid of variable domain. In the absence of light chain expression, the shortened γ chains were retained intracellulary and were subsequently degraded within 12 h. COM neoplastic plasma cells contained short γ1 heavy chain transcripts in which the leader peptide exon was directly joined to the CH1 exon using the regular splice sites. However, study of the productive γ gene showed that the skipped variable exon was bounded by normal splicing signals and that the adjacent intron organization was not altered. Since this unusual splicing pattern was maintained when COM γ gene was transfected in murine plasmocytoma cells, exon skipping possibly relates to the modified structure of COM variable region. The latter showed a 2‐base pair deletion introducing a translation frameshift in the Vh region and a DNA insertion at the VH‐DJH junction consisting in a perfect duplication of the first 54 nucleotides of the recombined D JH segment. The lack of light chain production by COM cells was explained by alterations of the variable region of the rearranged χ gene leading to abnormally spliced transcripts.
The assembly of H2‐Kb class I molecules translated in vitro requires oxidized glutathione and peptide
Authors: Bijlmakers Mariejose J. E. , Neefjes Jacques J. , Wojcik‐Jacobs Eldine H. M. , Ploegh Hidde L. 
Published: March 2007

AbstractAssociation of the mouse major histocompatibility complex (MHC) class I heavy chain H2‐Kb with mouse β2‐microglobulin (β2m) was studied in an in vitro translation system. Formation of stable class I complexes was found to be dependent on the presence of presentable peptides and oxidized glutathione, which promotes the formation of disulfide bridges. Translocation of peptides into microsomes was demonstrated by showing that a radioiodinated peptide containing an N‐glycosylation acceptor site became glycosylated. Class I complex formation was observed only when heavy chains and β2m were translated simultaneously, and thus occurs in the microsomes and not after their solubilization. However, peptide binding takes place only after solubilization of the microsomes. The class I complexes translated in vitro show the same specificity and length preference for peptides as their counterparts in RMA‐S cells. Assembly of in vitro translated class I complexes was found to occur also in the absence of peptides, resulting in the formation of unstable molecules that are stabilized by incubation with peptides.
Fetal thymocyte potential for T cell receptor Vγ3‐Jγ1 junctional modification
Authors: Larché Mark , Hurwitz Julia L. 
Published: March 2007

AbstractJunctional modifications of T cell receptor (TcR) and immunoglobulin (Ig) gene joining regions provide great diversity to respective protein repertoires. The addition of non‐germ‐line‐encoded nucleotides (N‐regions) in the V‐Jγ junction is one such modification which is developmentally regulated, rarely evident in the fetal animal, but common in the adult. A question has recently arisen as to whether developmentally patterned N‐region additions in V‐Jγ joins are a reflection of T cell progenitors which are committed to particular types of rearrangement prior to the event, or of changing environmental influences on uncommitted cell populations. To address this question with regard to theVγ3‐Jγ1 join, T cells were examined in the fetal thymic organ culture (FTOC), a system with which the environment of early progenitor cells could be deliberately altered. At various times following FTOC initiation, cells were isolated for examination by the polymerase chain reaction, cloning and sequencing. Vγ3‐Jγl sequences within genomic DNA as well as cDNA were evaluated. Data from these studies revealed frequent N‐region additions within V‐Jγ joins among day 14 fetal thymocyte populations, a situation dissimilar from that in vivo. Also dissimilar from the in vivo situation was the degree of exonuclease activity evident in FTOC. The canonical Vγ3‐Jγl join (a frequent junction lacking N‐region addition) was recognized in all experiments, but was least common among DNA versus cDNA sequences. Results illustrate that early progenitor cell populations are not programmed to exclude junctional modifications from Vγ3‐Jγ1 joins.
The role of the interleukin‐2 (IL‐2)/IL‐2 receptor pathway in MRL/lpr lymphadenopathy: The expanded CD4−8− T cell subset completely lacks functional IL‐2 receptors
Authors: Tanaka Toshiyuki , Yasuhiko  , Nagasaka  , Kitamura Fujiko , Kuida Keisuke , Suwa Hiroshi , Miyasaka Masayuki 
Published: March 2007

AbstractAutoimmune MRL/MP‐lpr/lpr (MRL/lpr) mice spontaneously develop a systemic lupus erythematosus‐like disease accompanied by a profound lymphadenopathy that consists of CD4−8−B220+ a P T cells. By the use of cross‐linking experiments with radiolabeled interleukin‐2 (IL‐2), these abnormal T cells have been reported to constitutively express the IL‐2 receptor β chain (IL‐2Rα), a signal transducing component of IL‐2R, in the absence of the a chain (IL‐2Rα).To critically reevaluate the role of the IL‐2/IL‐2R pathway in the pathogenesis of lymphadenophathy we examined expression of the IL‐2Rα and IL‐2Rβ in MRL/lpr mice by 125I‐IL‐2 binding analysis and also by flow cytometric analysis using monoclonal antibodies against each component of the receptor. We found that, contrary to the previous report, the CD4−8−B220+ α β T cells in lymph node (LN) of MRL/lpr mice were negative for both IL‐2Rα and IL‐2Rβ expression. The lpr liver CD4−8−B220+ a P T cells that had been implicated in the genesis of these abnormal LN T cells were also negative for IL‐2Rβ expression. Therefore, our results indicate that the IL‐2/IL‐2R system plays little role, if any, in the expansion of abnormal CD4−8− B220+ α β T cells in MRL/lpr mice.
Age‐related changes of T cell subsets in intestinal intraepithelial lymphocytes of mice
Authors: Takeuchi Makoto , Miyazaki Hiroyuki , Mirokawa Katsuku , Yokokura Tenio , Yoshikai Yasunobu 
Published: March 2007

AbstractAge‐related changes in T cell subsets were examined in intestinal intraepithelial lymphocytes (i‐IEL), which contain unique T cells differentiating extrathymically. In 2‐month‐old mice bred under conventional condition, i‐IEL consisted of a large number of CD4−CD8α/α+ cells bearing either T cell receptor (TcR)α/β or TcRγ/δ and only a few CD4+CD8α− cells. In aged mice (6 months old and 24 months old), unique CD4+CD8α/α+ i‐IEL bearing TcRα/β increased in number and conversely the proportion of TcRγ/δ+ i‐IEL was decreased. Such an increase in number of CD4+CD8α/α+ cells was detected in i‐IEL from aged (14‐months old) nude mice, but not in aged (14 months old) germ‐free mice, suggesting that a significant fraction of TcRα/β T cells such as CD4+CD8α+ i‐IEL can develop along an extrathymic pathway under the influence of intestinal microflora with age.
Conservation of T cell receptor usage by HLA B27‐restricted influenza‐specific cytotoxic T lymphocytes suggests a general pattern for antigen‐specific major histocompatibility complex class I‐restricted responses
Authors: Bowness Paul , Moss Paul A. H. , Rowland‐Jones Sarah , Bell John I. , McMichael Andrew J. 
Published: March 2007

AbstractEight HLA B7‐restricted influenza A virus nucleoprotein 383–391‐specific cytotoxic T lymphocyte (CTL) clones were obtained from three unrelated donors following natural infection. T cell receptor (TcR) usage was studied using the “anchored” polymerase chain reaction. TcR α‐chain usage was restricted with three predominant Vα (Vα 12.1, 14.1, 22) and two predominant Jα segments. β‐chain variable‐region usage was also conserved, with Vβ7 being used by five clones despite contributing less than 2% of peripheral blood lymphocyte Vβ sequences of one individual studied. The TcR β‐chain junctional region was highly conserved even between CTL clones from unrelated individuals, with a negatively charged amino acid, contributed to by N‐region addition, encoded at position 97 in all but two clones. This study shows that peptide‐specific HLA B27‐restricted CTL following influenza virus infection use very similar TcR and, when considered with previous studies, suggests a pattern of TcR conservation for major histocompatibility complex class I‐restricted responses. No difference in TcR usage was detected between one healthy donor and two with HLA B27‐associated arthritis.
Fine specificity of monoclonal antibodies directed at human T cell receptor variable regions: Comparison with oligonucleotide‐driven amplification for evaluation of Vβ expression
Authors: Diu Anita , Romagné Francois , Genevée Catherine , Rocher Corinne , Bruneau Jean‐Michel , David Alain , Praz Françchise , Hercend Thierry 
Published: March 2007

AbstractSeven distinct anti‐human T cell receptor (TcR) V region monoclonal antibodies (mAb) were generated by immunizing mice with either human T cell lines or transfected murine cells expressing human TcR Vβ genes. The specificity of these reagents was determined as follows: T cells recognized by each mAb were purified from the peripheral blood of healthy donors and TcR transcripts expressed in these cells were analyzed using oligonucleotide‐driven amplification and cDNA sequencing. Four mAb were found to delineate the Vβ3, Vβ8,Vβ17 and Vβ19 subfamilies, respectively. The remaining reagents recognize subsets within the Vβ2,Vβ5 and Vβ13 subfamilies. Reactivity of the mAb with circulating T cells from 18 unrelated healthy individuals was determined. Limited variability was found from an individual to another. In four donors, mAb staining was compared to oligonucleotide‐driven amplification for evaluation of Vβ3, Vβ8,Vβ17 and Vβ19 subfamily expression in the peripheral blood. Although the V gene subfamily‐specific oligonucleotides used in this study belong to a carefully controlled series, our results show that this method does not give an accurate estimate of the percentage of peripheral T cells expressing a given TcR β chain. The present data confirm the necessity to establish a complete set of well‐characterized monoclonal reagents to study human T cell responses.
Evidence for clonal anergy as a mechanism responsible for the maintenance of transplantation tolerance
Authors: Braun Michel Y. , McConnack Ann , And Gillian Webb , Batchelor J. Richard 
Published: March 2007

AbstractThe main stimulus triggering early acute allograft rejection is known to be delivered by the allogeneic “passenger” leukocytes present within the grafts. Once these cells have been replaced by cells of recipient origin, subsequent rejection episodes are generally less frequent and less acutely destructive. How this replacement affects the cell populations responsible for allograft rejection is not known. Here we report that rat alloreactive non‐cytotoxic AS (RT11) anti‐August (RT1C) CD4+ T cells, that were shown to be specific for RT1.BC+ August spleen stimulators, were able to cause acute rejection of normal August kidney allografts transplanted into sublethally irradiated AS recipients. These cells, however, failed to reject passenger cell‐depleted (PCD) August kidneys, despite the substantial expression of RT1.BC+ products on the graft tubular epithelium. In experiments in vitro, August kidney tubular epithelial cells expressing RT1.BC+ antigens were found to be unable to stimulate the alloreactive T cells to proliferate. Moreover, preincubation with class II‐positive August kidney epithelial cells specifically abrogated the alloreactivity of the T cells. Adding recombinant interleukin‐2, however, restored the response to alloantigens. These results are consistent with the hypothesis that T cell populations capable of mediating early acute allograft rejection are different from those mediating late rejection, when donor passenger leukocytes are no longer present. They also suggest clonal anergy as one of the mechanisms responsible for maintaining long‐term transplantation tolerance.
Occurrence of a silencer of the interleukin‐2 gene in naive but not in memory resting T helper lymphocytes
Authors: Mouzaki Athanasia , Rungger Duri , Tucci Alessandra , Doucet Arlette , Zubler Rudolf H. 
Published: March 2007

AbstractIn the immune system the first activation of a naive T cell by antigen is a key step in the shaping of the peripheral T cell specificity repertoire and maintenance of self‐tolerance. In the present study, analysis of the interleukin‐2 (IL‐2) gene activation shows that naive human helper T cells (cord blood CD4+ T cells, adult CD4+CD45RO− T cells) regulate IL‐2 transcription by a mechanism involving both a silencer and an activator acting on the purine‐rich IL‐2 promoter elements (NF‐AT binding sites). By contrast, memory cells, either in vitro activated helper T cells reverting to a resting state, or CD4+ T (memory) clones, or CD4+CD45RO+ T cells isolated ex vivo, no longer have a silencer. Their IL‐2 transcription seems to be controlled solely by the transition from inactive to active functional state of a positive transcription factor binding to these promoter elements as well as its cytoplasmic or nuclear location: in resting memory T cells the activator is located in the cytoplasm and is inactive, whereas in stimulated cells it is functional in promoting transcription and now resides in the nucleus. Thus, the regulation of the gene coding for the main T cell growth factor changes irreversibly after the first encounter of T cells with antigen. It is most likely that the presence of a silencer contributes to the more stringent activation requirements of naive CD4+ T cells.