bluuebunny/crossref_metadata_2025_split huggingface dataset:
Human peripheral blood γδ T cells are uniformly sensitive to destruction by the lysosomotropic agents leucine methyl ester and leucyl leucine methyl ester
Authors: Pechhold Klaus , Kabelitz Dieter 
Published: March 2007

AbstractTreatment of peripheral blood mononuclear cells (PBMC) with the lysosomotropic agent leucine methyl ester (Leu‐OMe) eliminates monocytes/macrophages and cytotoxic lymphocytes including CD3− CD16+ natural killer (NK) cells and a fraction of T cell receptor (TcR)αβ+ CD8+ T cells. We report that freshly isolated peripheral blood γδ T cells are highly sensitive to Leu‐OMe treatment as well. After incubation of PBMC with 5 mM Leu‐OMe or incubation of purified T cells with 50 μ.M leucyl leucine methyl ester (Leu‐Leu‐OMe) and subsequent overnight culture, CD3−CD16+ NK cells and γδ T cells were no longer detectable by immunofluorescence analysis. The two major γδ T cell subsets Vγ9+Vδ2+ and Vγ9‐Vδ1+ were equally susceptible to Leu‐OMe and Leu‐Leu‐OMe treatment. The elimination of Vγ9+ T cells by Leu‐OMe treatment was confirmed in functional assays. Stimulation of peripheral blood T cells with killed mycobacteria resulted in selective expansion of Vγ9+ T cells. In contrast, no activation of γδ T cells was elicited in Leu‐OMe‐treated responder T cells stimulated with killed mycobacteria.
Peripheral clonal deletion of superantigen‐reactive T cells is enhanced by cortisone
Authors: Lussow Alexander R. , Crompton Tessa , Karapetian Ochine , MacDonald H. Robson 
Published: March 2007

AbstractThe Tcell receptor (TcR) Vβ‐specific expansion, deletion and induction of nonresponsiveness among murine T cells responding to superantigens in the periphery has been well characterized. Here we demonstrate that clonal deletion of staphylococcal enterotoxin (SE) B‐reactive Vβ 8.2+ cells can be significantly increased when mice are injected with hydrocortisone (HC) following superantigen stimulation in vivo. The induced sensitivity to HC persists for at least 30 days after SEB injection, making it unlikely that proliferating cells were uniquely responsible for the enhanced deletion. Superantigen‐induced HC sensitivity was a general phenomenon and could also be observed among Vβ 11+ cells after the injection of SEA. Experiments conducted on thymectomized mice indicated that HC‐sensitive, SEB‐responsive cells could not be accounted for by rapidly produced, immature lymphocytes recently exported from the thymus. Further, Vβ 8.1+ peripheral lymphocytes from TcR transgenic mice expressing the Mls‐1a superantigen were sensitive to HC. These results imply that the majority of cells remaining after superantigen‐induced clonal expansion and deletion in vivo have indeed reacted with the superantigen. Implications for differential superantigen recognition by Tcells expressing the same TcR Vβ domain, perhaps due to a significant Vα contribution to the interaction in vivo, are discussed.
Human immunodeficiency virus gp120 and derived peptides activate protein tyrosine kinase p56Ick in human CD4 T lymphocytes
Authors: Hivroz Claire , Mazerolles Fabienne , Soula Mahdhia , Fagard Rémi , Graton Sophie , Meloche Sylvain , Sekaly Rafick P. , Fischer Alain 
Published: March 2007

AbstractHuman immunodeficiency virus binds to CD4 T lymphocytes by interaction between its envelope glycoprotein gpl20 and the CD4 molecule. The latter is non‐covalently associated with a src‐related tyrosine kinase, p56lck. CD4 cross‐linking increases the activity of p56lck, leading to phosphorylation of several cellular substrates. We report here that gpl60/120 increases both the autophos‐phorylation of p56lck and its enzymatic activity (reflected by phosphorylation of an exogeneous substrate) in normal T cells and the HUT78 CD4+ T cell line. This effect was detectable 5 min after activation and persisted for 40 min in normal T cells. It did not require gpl20 cross‐linking and was associated with phosphorylation of tyrosine residue on several proteins, as shown by phosphotyrosine Western blot analysis. The pattern of proteins phosphorylated on tyrosine residues in response to gpl20 activation was distinct from that induced by anti‐CD4 antibodies. p56lck activation required its association with CD4, since p56lck activity was not modified in HUT78 T cell lines expressing a truncated or mutated form of CD4 unable to associate with p56lck. Peptides mimicking residues 418 to 434 and 449 to 464 of HIV‐1 Bru gpl20, regions known to participate in gpl20 binding to CD4, also increased p56lck activity and triggered phosphorylation of similar substrates. Taken together, these results show that gpl60/120 and derived peptides can transiently increase p56lck activity without the need for CD4 cross‐linking. This activation led to a specific pattern of tyrosine phosphorylation on cellular proteins that may be of significance in the biological effects of the gpl20/CD4 interaction, e.g. syncytium formation and inhibition of T cell activation.
Peptide‐induced memory (IgG) response, cross‐reactive with native proteins, requires covalent linkage of a specific B cell epitope with a T cell epitope
Authors: Zegers Netty D. , van Holten Conny , Claassen Eric , Boersma Wim J. A. 
Published: March 2007

AbstractIn order to raise antibodies synthetic peptides are often coupled to a carrier protein to provide the necessary T cell determinants. Alternatively, a short synthetic determinant with a distinct sequence motif which can be presented by major histocompatibility complex (MHC) class II toT cells, can be linked directly to a B cell epitope. Recently, it has been suggested that covalent linkage between a class II‐presentable T helper peptide and a B cell epitope is not required to induce antibodies against a B cell determinant (Sarobe et al., Eur. J. Immunol. 1991. 21: 1555). Therefore, we investigated the ability of an H‐2d‐restricted T cell determinant (AA 111–120 FERFEIFPKEK) from the influenza virus hemagglutinin, to support B cell responses to different proven B cell determinant peptides, derived from human α1‐antitrypsin. Antibodies against B cell epitopes crossreactive with native α1‐antitrypsin could be raised only when these B epitope peptides were covalently coupled to the T cell determinant through a peptide bond. No antibodies were raised against the B cell epitope when the free peptides (Tand B cell epitopes) were just mixed or when the T cell epitope was conjugated via m‐maleimidobenzoyl succinimide ester or bis‐maleimidohexane to the B cell determinant. Antibodies against the T cell determinant were raised in all cases, regardless of the mode of presentation: just mixed with or covalently coupled to the B cell determinant. The results indicate that a covalent bond between T cell and B cell determinants in general is needed to induce anti B cell determinant antibodies cross‐reactive with the native protein.
Evaluation of the C‐terminal C5a effector site with short synthetic C5a analog peptides
Authors: Köhl Jörg , Lübbers Bettina , Klos Andreas , Bautsch Wilfried , Casaretto Monika 
Published: March 2007

AbstractBiological activities have been determined for a series of 18 peptides based on the C‐terminal sequence of human or rat C5a. Lysosomal enzyme release was tested in two cell types, the promyelotic leukemia cell line U937 and polymorphonuclear leukocytes. In addition, an ATP‐release assay with guinea pig platelets was performed. It was demonstrated that the C‐terminal octapeptide 67‐74 of human C5a represents the minimal sequence required to induce a measurable biological signal in all assays. Extending this peptide to a length of 21 amino acids produced at best only a slight enhancement of potency. Amino acid replacements with either tryptophanyl or phenylalanyl residues in positions between 65–69 either increased potency (at position 67), or abrogated potency (at position 66) in the two lysosomal enzyme assays. N‐terminal acylation with the fluorenylmethoxy‐carbonyl‐aminohexanoyl group slightly enhanced C5a potency. In desensitization experiments with guinea pig platelets all peptides with a C5a activity were able to desensitize not only the C5a but also the C3a responses.
Monoclonal antibodies to the integrin α−4 subunit inhibit the murine contact hypersensitivity response
Authors: Chisholm Patricia L. , Williams Cynthia A. , Lobb Roy R. 
Published: March 2007

AbstractLymphocyte‐endothelial cell recognition is an active multistep process central to the pathophysiology of inflammation. In vitro models of lymphocyte adhesion predict that the β1 integrin very late antigen−4 (VLA−4), an activation‐dependent adhesion receptor, can mediate the firm sustained attachment required for the extravasation of memory lymphocytes. We have used murine contact hypersensitivity as an in vivo model in which to evaluate the role of α−4 integrins in an evolving inflammatory response. We demonstrate that the intravenous administration of 75μg of the anti‐α−4 specific monoclonal antibodies Rl‐2 or PS/2 4–6 h prior to challenge significantly inhibits the efferent response of 2,4 dinitrofluorobenzene, or oxazalone‐sensitized mice. The disease‐modifying effect of anti‐α4 treatment was evident as a 50–60% reduction in the ear swelling response. By histological analysis treated animals scored lower for edema, number of epidermal lesions and degree of leukocyte infiltration. Antibody‐treated animals have elevated numbers of circulating mononuclear leukocytes present in the same relative ratio as untreated control animals, suggesting that the inhibitory effect was not due to antibody‐dependent cellular depletion of effector lymphocytes. These data are consistent with a central role for VLA‐4 in the pathophysiologic process of inflammation.
Protection against autoimmune disease by bacterial agents. II. PPD and pertussis toxin as proteins active in protecting mice against experimental autoimmune encephalomyelitis
Authors: Ben‐Nun Avraham , Yossefi Sara , Lehmann Dan 
Published: March 2007

AbstractBordetella pertussis and Mycobacterium tuberculosis, routinely used to promote the development of autoimmune disease, were recently reported to also be effective in inducing protection against an autoimmune disease. Thus, we previously demonstrated that SJL/J and (SJL/J x BALB/c)F1 mice that are genetically susceptible to experimental autoimmune encephalomyelitis (EAE) become highly refractory to the induction of the disease following their exposure to B. pertussis and M. tuberculosis. In the present study, the pertussis toxin (PT) from B. pertussis and the purified protein derivative (PPD) of M. tuberculosis, were found to be sufficient to fully protect against EAE and thus may be the major bacterial components responsible for conferring protection. The 65‐kDa heat‐shock protein played only a marginal role in the protection against EAE induced by these bacteria. Both PT and PPD were protective when given before, but not after, the encephalitogenic challenge, and minute amounts (5–50 ng) emulsified in oil were sufficient to confer long‐lasting resistance to EAE. The effect of PT or PPD on EAE differed from that of mitogens or bacterial superantigens, suggesting that their protection ability was not attributable merely to mitogenic or superantigenic properties.The mechanism of protection is not yet clear. Preliminary studies revealed a complex mechanism of protection whereby PPD and PT may operate differently. Thus, only PPD‐induced, but not PT‐induced, protection was transferrable by CD4+ T lymphocytes bearing an αγ Tcell antigen receptor. Neither PT nor PPD had a protective effect on EAE mediated by preformed pathogenic T lymphocytes and it is most likely that they exert their protection by affecting the development of such T lymphocytes. How bacteria such as B. pertussis and M. tuberculosis can either enhance the development of an autoimmune disease or protect against the disease is not yet clear. However, identifying PT and PPD as the bacterial components active in protection may allow a better understanding of the modulatory effects of bacteria and point to the potential use of such bacterial products in immunomodulation of autoimmune diseases.
APO‐1 mediated apoptosis or proliferation in human chronic B lymphocytic leukemia: Correlation with bcl‐2 oncogene expression
Authors: Mapara Markus Y. , Bargou Ralf , Zugck Christian , Döhner Hartmut , Ustaoglu Ferman , Jonker Richard R. , Krammer Peter H. , Dörken Bernd 
Published: March 2007

AbstractWe studied induction of apoptosis in several human malignant B cells from chronic lymphocytic leukemias (BCLL) by triggering the APO‐1 antigen. The APO‐1 antigen was found to be expressed on the surface of malignant B cells. In BCLL cells from most patients, APO‐1 antigen expression increased following in vitro activation by Staphylococcus aureus Cowan I (SAC) or interleukin‐2 (IL‐2). In certain cases of BCLL co‐stimulation with SAC plus IL‐2 resulted in a synergistic up‐regulation of the APO‐1 antigen on the cell surface and prepared BCLL cells for monoclonal antibody anti‐APO‐1 mediated apoptosis. Interestingly, bcl‐2 mRNA expression decreased upon stimulation with SAC plus IL‐2, whereas SAC or IL‐2 alone did not affect the level of bcl‐2 expression. Thus, in these BCLL cells induction of anti‐APO‐1‐mediated apoptosis appeared to be correlated with bcl‐2 mRNA down‐regulation. One informative BCLL, however, with a similar pattern of APO‐1‐antigen expression, did not show SAC plus IL‐2‐dependent bcl‐2 down‐regulation. Surprisingly, these cells proliferated in response to anti‐APO‐1 only when cells were co‐stimulated with SAC plus IL‐2. Our data suggest that down‐regulation of bcl‐2 prepares BCLL cells for induction of APO‐1‐mediated apoptosis. In addition they demonstrate that triggering of the APO‐1 antigen may also lead to the induction of proliferation in special cases of BCLL.
Role of cAMP in regulating cytotoxic T lymphocyte adhesion and motility
Authors: Valitutti Salvatore , Dessing Mark , Lanzavecchia Antonio 
Published: March 2007

AbstractWe investigated the functional role of the cAMP pathway in human cytotoxic T lymphocyte (CTL)‐target interaction. Pharmacological increase of intracellular cAMP concentration ([camp]i) inhibits killing, especially at low effectorto‐target ratios, suggesting an inhibitory effect on CTL recycling. We show that this inhibitory effect is primarily at the level of conjugate formation. Pharmacological increase in [cAMP]i, as well as treatment with cytochalasin D, results in a “rounding up” of the CTL and inhibition of the dramatic changes in shape that occur when a CTL forms a conjugate, even with an irrelevant target. In addition, pharmacological increase in [camp]i affects the cytoskeleton of the CTL since it induces a decrease of filamentous actin, as detected by flow cytometry on phalloidin‐stained CTL, and a stabilization of microtubules, as detected by increased resistance to the disrupting action of nocodazole.In mature CTL (but not in their immature precursors), T cell receptor triggering by specific targets results in a measurable increase in cAMP levels and strongly synergizes with adenylyl cyclase activators such as prostaglandin E2, cholera toxin and forskolin. We suggest that T cell receptor triggering may induce accumulation of cAMP that interferes with cytoskeleton function and, thus, terminates CTL secretion and adhesion. These effects of cAMP are rapidly reversible and may regulate CTL recycling.
Peripheral selection of antigen receptor junctional features in a major human γδ subset
Authors: Davodeau François , Peyrat Marie Alix , Hallet Marie Martine , Houde Isabelle , And Henri Vie , Bonneville Marc 
Published: March 2007

AbstractRecent studies demonstrating the existence of murine γδ T cell subsets with structurally identical T cell receptors (TcR) suggest that unlike αβ T cells, some γδ T cells are specialized in the recognition of a limited number of monomorphic antigens. However, this question still remains open in humans, since the TcR structural diversity of their peripheral γδ T cells was shown to be extensive. Here we have analyzed in detail the TcR chain genes expressed by human Vγ9+Vδ2+ peripheral blood lymphocytes (PBL), a major peripheral γδ T cell subset in adults and present evidence for an antigen‐driven peripheral selection of both TcR γ and δ junctional motifs among these cells. First, it is shown that the proportion of Vγ9+Vδ2+ cells expressing the V9JPC1 γ chain is much higher among PBL than among thymus‐derived clones, indicating that preferential use of this Jγ segment is not due to pairing or combinatorial constraints. Second, analysis of V9JPC1 γ transcripts derived from Vγ9+Vδ2+ PBL clones revealed a high prevalence of a unique V9JP γ sequence with limited “N” nucleotide additions and VJ trimming, which could not be accounted for by enzymatic or antigen‐independent structural limitations. Third, the TcR b chain expressed by most Vγ9+Vδ2+ PBL clones, though diverse in amino acid composition and length, carried a highly distinctive junctional motif, found at a much lower frequency among V2DJδ sequences derived from Vγ9−Vδ2+ PBL or Vγ9+Vδ2+ thymocytes. Together, these results which demonstrate shared γ and δ junctional features by cells using unique Vγ and Vδ genes, suggest that in vivo selection of Vγ9+Vδ2+ lymphocytes is mediated by a highly restricted number of nominal ligands.
Nucleotidic sequence analysis of the variable domains of four human monoclonal IgM with an antibody activity to myelin‐associated glycoprotein
Authors: Mariette Xavier , Tsapis Andréas , Brouet Jean‐Claude 
Published: March 2007

AbstractWe determined the nucleotide sequence of the VL and VH regions of four human monoclonal IgM directed to myelin‐associated glycoprotein (MAG) and a nerve glycolipid, the sulfated glucuronic paragloboside (SGPG). Clonal lymphoblastoid cell lines (three cases) and an heterohybridoma (one case) secreting anti‐MAG IgM were derived from patients' blood B cells.Vx genes derived from the single germinal VxIV (two cases), the VxId and the VxIIIa Humkv328h5 genes. Vh genes derived from the VhIII 9.1 germinal gene (or a closely related gene) in two cases, whereas two others possibly represent new members of the VhIII or VhI variability subgroups. There was no obvious restriction in the use of Jx Jh and Dh segments. Somatic mutations were predominantly found in the CDR3 of the VxIV genes with an overall ratio of replacement over silent mutations of 7/0. The sequence of two VhIII genes exhibited five replacement mutations in CDR in comparison to that of the germ‐line 9.1 gene.Although some Vgenes are likely to be overrepresented among anti‐MAG IgM, the diversity of the immune repertoire for MAG and SGPG explains the lack of easily detectable public idiotopes among these IgM. This last finding, as well as a high ratio of replacement versus silent nucleotide mutations in the CDR of VL and probably VH genes, suggest that the pathogenesis of these monoclonal antibodies (and of the associated lymphoplasmocytic disorder) differs from that of other previously characterized monoclonal autoantibodies such as rheumatoid factors and cold agglutinins.
The major histocompatibility complex‐encoded proteasome component LMP7: alternative first exons and post‐translational processing
Authors: Glynne Richard , Kerr Lesley‐Anne , Mockridge Ian , Beck Stephan , Kelly Adrian , Trowsdale John 
Published: March 2007

AbstractThe LMP7 gene maps to the major histocompatibility complex class II region. The derived protein sequence shares homology with N‐terminal amino acid sequence from proteasome subunits (Glynne, R., Powis, S. H., Beck, S., Kelly, A., Kerr, L.‐A. and Trowsdale, J., Nature 1991. 353: 357) and it has been suggested that LMP7 is involved in the degradation of endogenous antigens prior to their presentation through class I (Robertson, M., Nature 1991. 353: 300). We have isolated a second LMP7 transcript which has a different first exon to the published sequence. Both transcripts were expressed in cell lines from a number of tissues and both responded to inferferon‐γ. An anti‐LMP7 antiserum precipitated proteins similar in their migration on sodium dodecyl sulfate‐polyacrylamide gel electrophoresis to those precipitated by an anti‐proteasome serum. Western blot analysis of anti‐proteasome precipitates demonstrated that the LMP7 protein is incorporated into the proteasome but has a molecular mass of 23 kDa, 7 kDa smaller than expected from the derived protein sequence of either of the cDNA. A pulse‐chase experiment indicated that post‐translational cleavage of the LMP7 N terminus precedes the formation of the 23‐kDa proteasome subunit. To our knowledge, LMP7 provides the first biochemical evidence for such processing of proteasome components.
Identification of two distinct CD5‐ B cell subsets from human tonsils with different responses to CD40 monoclonal antibody
Authors: Dono Mariella , Zupo Simona , Masante Raffaella , Taborellin Giuseppe , Chiorazzp Nicholas , Ferrarini Manlio 
Published: March 2007

AbstractThis study investigated the response of different CD5− B cell subsets to CD40 monoclonal antibody (mAb) in various combinations with interleukin (IL)‐4 or rabbit anti‐human μ chain antibody (a‐μ‐Ab). The different CD5 B cell subsets were isolated from tonsillar B cell suspensions depleted of CD5+ B cells and subsequently fractionated on Percoll density gradients.While resting CD5+ B cells proliferated and produced IgM molecules in response to a‐μ‐Ab, IL‐4 and CD40 mAb as well as to Staphylococcus aureus Cowan strain I (SAC) and IL‐2, resting CD5− B cells, which were co‐purified in the same 60% Percoll fractions, consistently failed to respond. These cells were, however, activated by the stimuli employed, as demonstrated by their capacity to express the surface activation markers CD69, CD25 and CD71. Resting CD5+ B cells had the typical phenotype of mantle zone B cells (IgM+ IgD+ CD39+ CD38− CD10− CDw75dim), whereas resting CD5− B cells were CD38− CD39− CD 10− CDw75 intermediate and expressed surface IgM but relatively little surface IgD and could not be classified as mantle zone or germinal center cells. The finding that purified germinal center cells (CD38+ CD10+ CD39− CDw75bright, IgG+) responded to CD40 mAb and IL‐4 and also to SAC plus IL‐2 further underlined the differences to resting CD5− B cells. However, some of the data collected suggest possible relationships between CD5− B cells and germinal center cells.The CD5− B cells isolated from the 50 % Percoll fraction proliferated in response to a‐μ‐Ab, CD40 mAb and IL‐4 as well as to SAC and IL‐2. These cells had the same mantle zone B cell phenotype as the CD5+ B cells, but their capacity to respond to the stimuli in vitro was unrelated to a possible contamination with CD5+ B cells, as documented by the appropriate controls. Furthermore, upon exposure to SAC or phorbol esters, the large majority of CD5− B cells from the 50 % Percoll fraction did not express surface CD5 and there was very little if any accumulation of CD5 mRNA. Finally, most of the cycling cells in the stimulated CD5− B cells did not express CD5.The CD5− B cells from the 50 % Percoll fraction were comprised of a consistent proportion of cells that expressed surface activation markers. The removal of these cells abrogated the capacity of the suspensions to respond to the stimuli in vitro, possibly suggesting that these cells additional activation signals in vivo which were essential to acquire the capacity to respond and that could not be reproduced in vitro.The present study underlines the phenotypic and functional heterogeneity of CD5− B cells and contributes to the identification of two subsets of these cells which differ in phenotype, tissue distribution and in vitro responses to different stimuli.